[Federal Register Volume 91, Number 133 (Tuesday, July 14, 2026)]
[Proposed Rules]
[Pages 43154-43297]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-14112]
[[Page 43153]]
Vol. 91
Tuesday,
No. 133
July 14, 2026
Part II
Environmental Protection Agency
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40 CFR Parts 86, 1036, et al.
Amendments and Nonconformance Penalties for Model Year 2027 and Later
Heavy-Duty Highway Engines and Amendments to Inducement Provisions for
SCR-Equipped Diesel Engines; Proposed Rule
Federal Register / Vol. 91 , No. 133 / Tuesday, July 14, 2026 /
Proposed Rules
[[Page 43154]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 86, 1036, 1037, 1039, 1065, and 1071
[EPA-HQ-OAR-2026-0728; FRL 12756-01-OAR]
RIN 2060-AW83
Amendments and Nonconformance Penalties for Model Year 2027 and
Later Heavy-Duty Highway Engines and Amendments to Inducement
Provisions for SCR-Equipped Diesel Engines
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing
regulatory amendments to certain compliance provisions and test
procedures related to model year (MY) 2027 and later heavy-duty highway
engines. These amendments would include changes to the regulatory
useful life periods and the emission-related warranty periods. The EPA
also proposes to add clarity to certain regulatory compliance
provisions and correct errors in the regulations to support the MYs
2027 and later program for heavy-duty highway engines and vehicles.
This includes certain amendments related to provisions adopted in
January 2023 as well as other provisions adopted in earlier rules. The
EPA also proposes to make nonconformance penalties (NCPs) available to
manufacturers of medium heavy-duty engines (Medium HDE) and heavy
heavy-duty engines (Heavy HDE) beginning in MY 2027. In addition, the
EPA proposes to amend the requirements for selective catalytic
reduction (SCR) system inducement provisions for newly manufactured
diesel-fueled highway engines and vehicles (i.e., light- and medium-
duty vehicles and heavy-duty engines) and nonroad engines and
equipment. The EPA is also considering new inducement guidance for in-
use highway and nonroad diesel engines, vehicles, and equipment.
DATES: Comments. Comments must be received on or before August 29,
2026. Comments on the information collection provisions submitted to
the Office of Management and Budget (OMB) under the Paperwork Reduction
Act (PRA) are best assured of consideration by OMB if OMB receives a
copy of your comments on or before August 13, 2026.
Public hearing: The EPA will hold virtual public hearings on July
29, 2026, starting at 9:00 a.m. Eastern Time and on July 30, 2026,
starting at 10:00 a.m. Eastern Time. If there is sufficient interest,
an additional day of hearings will be held on the subsequent day.
Please refer to the SUPPLEMENTARY INFORMATION section for additional
information on the public hearing. Information on the status of the
hearing and how to register can be found at https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-amendments-and-nonconformance-penalties.
ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2026-0728, by any of the following methods:
Federal eRulemaking Portal: www.regulations.gov (our
preferred method). Follow the online instructions for submitting
comments.
Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2026-0728 in the subject line of the message.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, OAR Docket EPA-HQ-OAR-2026-0728, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
Hand Delivery or Courier: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to www.regulations.gov, including personal information provided. For
detailed instructions on sending comments and additional information on
the rulemaking process, see the ``Public Participation'' heading of the
SUPPLEMENTARY INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: For information about this proposed
rule, contact James Sanchez, Transportation Sector Impacts & Standards
Division, Office of Transportation and Air Quality, Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
telephone number: (734) 214-4439; email address: [email protected].
SUPPLEMENTARY INFORMATION:
Public Participation
A. Written Comments
Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2026-
0728, at www.regulations.gov (our preferred method), or the other
methods identified in the ADDRESSES section. Once submitted, comments
cannot be edited or removed from the docket. The EPA may publish any
comment received to the Agency's public docket. Do not submit to the
EPA's docket at www.regulations.gov any information you consider to be
Confidential Business Information (CBI), Proprietary Business
Information (PBI), or other information the disclosure of which is
restricted by statute. If you choose to submit CBI or PBI as a comment
to the EPA's docket, please send those materials to the person listed
in the FOR FURTHER INFORMATION CONTACT section. Multimedia submissions
(audio, video, etc.) must be accompanied by a written comment. The
written comment is considered the official comment and should include
discussion of all points you wish to make. The EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system).
Please visit www.epa.gov/dockets/commenting-epa-dockets for additional
submission methods; the full EPA public comment policy; information
about CBI, PBI, or multimedia submissions; and general guidance on
making effective comments.
B. Participation in Virtual Hearing
The EPA will announce detailed information about the hearing as
described in ADDRESSES. The EPA will begin pre-registering speakers for
the hearing upon publication of this document in the Federal Register.
To register to speak at the virtual hearing, please send an email to
[email protected]. If you need additional help,
contact the person listed in the FOR FURTHER INFORMATION CONTACT
section.
Registration will be open through the last day of the hearing;
however, the EPA asks that you pre-register by July 22, 2026 if you
intend to testify or are requesting special accommodations such as the
services of an interpreter or audio description, please pre-register
for the hearing and describe your needs by July 22, 2026. The EPA may
not be able to arrange accommodations without advance notice.
The EPA will provide a general agenda for the hearing listing the
pre-registered speakers in approximate order at https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-amendments-and-nonconformance-penalties before the first day of the hearing. The
EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan
[[Page 43155]]
for the hearings to run either ahead of schedule or behind schedule.
Registration will be open through the last day of the hearing and the
EPA will make every effort to accommodate all speakers who join the
hearing, although preferences on speaking times may not be able to be
fulfilled, and special accommodations may not be available.
Each commenter will have up to three minutes to provide oral
testimony, though the final time limit may change and will be provided
to registered speakers before the first day of the hearing. The EPA may
ask clarifying questions during the oral presentations but will not
respond to the presentations at that time. Written statements and
supporting information submitted during the comment period will be
considered with the same weight as oral comments and supporting
information presented at the public hearing.
Please note that any updates made to any aspect of the hearing are
posted online at https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-amendments-and-nonconformance-penalties.
While the EPA expects the hearing to go forward as set forth above,
please monitor the Agency's website to determine if there are any
updates. The EPA does not intend to publish a document in the Federal
Register announcing updates.
C. Public Access to Voluntary Consensus Standards
Copies of ASTM standards identified in section III.E of this
preamble may be obtained from ASTM International, 100 Barr Harbor Dr.,
P.O. Box C700, West Conshohocken, PA 19428-2959, by calling (877) 909-
ASTM, or at www.astm.org. Copies of these standards have also been
placed in the rulemaking docket for this action. For the latest status
information on EPA Docket Center Reading Room services and docket
access, visit www.epa.gov/dockets/epa-docket-center-reading-room or
call (202) 566-1744. If you have a disability and the format of any of
these materials interferes with your ability to access the information,
please contact the EPA's Rehabilitation Act Section 508 (29 U.S.C.
794d) Program at www.epa.gov/accessibility/forms/contact-us-about-section-508-accessibility or via email at [email protected]. To enable
the EPA to respond in a manner most helpful to you, please indicate the
nature of the accessibility issue, the web address of the requested
material, your preferred format in which you want to receive the
material (electronic format (ASCII, etc.), standard print, large print,
etc.), and your contact information.
D. Docket
All documents in the docket are listed on the www.regulations.gov
website. A plain language summary of the rule is also available on the
www.regulations.gov website. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
the disclosure of which is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the internet
and will be publicly available only in hard copy form through the EPA
Docket Center at the location listed in the ADDRESSES section of this
document.
General Information
Does this action apply to me?
This action relates to companies that manufacture, sell, or import
into the United States motor vehicles, motor vehicle engines, and
nonroad engines and equipment. Potentially affected categories and
entities include the following:
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NAICS codes \a\ Sector title
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333618............................... Other Engine Equipment
Manufacturing.
336110............................... Automobile and Light Duty Motor
Vehicle Manufacturing.
336120............................... Heavy Duty Truck Manufacturing.
336310............................... Motor Vehicle Gasoline Engine and
Engine Parts Manufacturing.
336390............................... Other Motor Vehicle Parts
Manufacturing.
336999............................... All Other Transportation
Equipment Manufacturing.
333111............................... Farm Machinery and Equipment
Manufacturing.
333120............................... Construction Equipment
Manufacturing.
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\a\ NAICS Association. NAICS & SIC Identification Tools. www.naics.com/search search.
This table is not intended to be exhaustive but rather provides a
guide for readers regarding entities potentially affected by this
action. This table lists the types of entities that the EPA is aware
could potentially be affected by this action. Other types of entities
not listed in the table could also be affected. To determine whether
your entity is regulated by this action, you should carefully examine
the applicability criteria found in the regulation. If you have
questions regarding the applicability of this action to a particular
entity, consult the person listed in the FOR FURTHER INFORMATION
CONTACT section.
What action is the Agency taking?
The EPA is proposing regulatory amendments to compliance provisions
and test procedures related to the Agency's 2023 rule setting criteria
pollutant emission standards for MYs 2027 and later heavy-duty highway
engines. These amendments are intended to add clarity to the regulatory
compliance provisions and correct errors in the regulations.
What is the Agency's authority for taking this action?
Statutory authority for this proposed action comes from the Clean
Air Act (CAA) (42 U.S.C. 7401-7671q).
List of Acronyms
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Acronym Description
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AAF............................... Annual Adjustment Factor
ABT............................... Averaging, Banking, and Trading
AECD.............................. Auxiliary Emissions Control Device
ANSI.............................. American National Standards
Institute
ASTM.............................. ASTM International
ATA............................... American Trucking Associations
CAA............................... Clean Air Act
CARB.............................. California Air Resources Board
CCR............................... California Code of Regulations
CFR............................... Code of Federal Regulations
CNG............................... Compressed Natural Gas
CD................................ Charge Depleting
CO................................ Carbon Monoxide
COC............................... Cost of Compliance
CS................................ Charge Sustaining
DEF............................... Diesel Exhaust Fluid
DPF............................... Diesel Particulate Filter
DRIA.............................. Draft Regulatory Impact Analysis
DTSD.............................. Draft Technical Support Document
EMA............................... Truck & Engine Manufacturers
Association
EGR............................... Exhaust Gas Recirculation
EPA............................... Environmental Protection Agency
FEL............................... Family Emission Limit
FR................................ Federal Register
FTP............................... Federal Test Procedure
GVWR.............................. Gross Vehicle Weight Rating
HC................................ Hydrocarbons
HD................................ Heavy-Duty
HDE............................... Heavy-Duty Engine
ICP-MS............................ Inductively Coupled Plasma Mass
Spectrometer
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ISO............................... International Organization for
Standardization
LLC............................... Low Load Cycle
MC................................ Marginal Cost
MIL............................... Malfunction Indicator Light
MOVES............................. MOtor Vehicle Emission Simulator
MY................................ Model Year
NCP............................... Nonconformance Penalty
NG................................ Natural Gas
NMHC.............................. Nonmethane Hydrocarbon
NOX............................... Oxides of Nitrogen
NPRM.............................. Notice of Proposed Rulemaking
NTTAA............................. National Technology Transfer and
Advancement Act
OBD............................... Onboard Diagnostics
OEM............................... Original Equipment Manufacturer
OMB............................... Office of Management and Budget
PCA............................... Production Compliance Audit
PM................................ Particulate Matter
PR................................ Penalty Rate
PRA............................... Paperwork Reduction Act
RESS.............................. Rechargeable Energy Storage System
RFA............................... Regulatory Flexibility Act
RIA............................... Regulatory Impact Analysis
RPE............................... Retail Price Equivalent
SAE............................... SAE International
SCR............................... Selective Catalytic Reduction
SET............................... Supplemental Emission Test
SO2............................... Sulfur Dioxide
SVOC.............................. Semi-Volatile Organic Compounds
THC............................... Total Hydrocarbon Emissions
TSD............................... Technical Support Document
UL................................ Upper Limit
ULSD.............................. Ultra Low Sulfur Diesel
UMRA.............................. Unfunded Mandates Reform Act
UQS............................... Urea Quality Sensor
VOC............................... Volatile Organic Compounds
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Table of Contents
I. Executive Summary
A. Introduction
B. Need for Regulatory Action
C. Summary of the Major Provisions in This Proposal
D. Summary of the Impacts of This Proposal
II. Introduction
A. Background
B. Response to the 2023 Final Rule
C. Summary of the Proposal
D. Legal Authority
E. Reliance Interests
III. Proposed Compliance Provisions and Test Procedures
A. Emission-Related Warranty
B. Regulatory Useful Life Periods
C. Production Volume Allowance
D. Credit Flexibilities
E. Other Regulatory Amendments
IV. Nonconformance Penalties for Diesel-Fueled Medium HDE and Heavy
HDE
A. NCP Eligibility
B. Nonconformance Penalty Rates
C. Consideration of Other Methodologies and Factors for
Estimating MY 2027 NCPs
D. Migrating Regulation to 40 CFR Part 1071 and Proposed
Revisions to the Regulation
V. Improvements for SCR Reliability and Changes to DEF Inducements
for Highway Engines and Vehicles and for Nonroad Diesel Engines
A. Background
B. Recent Developments
C. The EPA's Proposed Inducement Revisions
D. Proposed Revisions To Improve SCR Reliability
E. Applying Proposed SCR Inducement Changes to Light-Duty
Vehicles, Medium-Duty Vehicles, and Nonroad Engines
F. Potential for Additional EPA Inducement Guidance for In-Use
Engines and Vehicles
VI. Program Costs
VII. Estimated Emissions Changes From the Proposed Program
Amendments
A. Emission Inventory Methodology
B. Emission Inventory Impacts
VIII. Air Quality Impacts of the Proposed Rule
IX. Projected Changes in Human Health and Welfare From the Proposed
Rule
X. Economic Impact Analysis
XI. Summary of Requests for Comment in This Proposed Rule
XII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
XIII. Statutory Provisions and Legal Authority
List of Subjects
I. Executive Summary
A. Introduction
In this action, the EPA proposes regulatory amendments to certain
compliance provisions and test procedures related to MYs 2027 and later
heavy-duty highway engines. These amendments would include changes to
the regulatory useful life periods and the emission-related warranty
periods. The EPA also proposes to add clarity to certain regulatory
compliance provisions and correct errors in the regulations to support
the MYs 2027 and later program for heavy-duty highway engines and
vehicles. This includes certain amendments related to provisions
adopted in January 2023 and other provisions adopted in earlier rules.
The EPA also proposes to make NCPs available to manufacturers of Medium
HDE and Heavy HDE beginning in MY 2027. In addition, the EPA proposes
to amend the requirements for SCR system inducement provisions for
newly manufactured diesel-fueled highway engines and vehicles and
nonroad engines and equipment.\1\ The EPA is also considering new
inducement guidance for in-use highway and nonroad diesel engines,
vehicles, and equipment.
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\1\ Throughout this preamble, the term ``inducements'' refers to
SCR-related strategies to induce operators to maintain appropriate
levels of high-quality DEF and not tamper with SCR systems. Engine
derating and vehicle speed restrictions have historically been
applied as the primary inducement for SCR systems. Engine derating
is a design strategy that reduces engine power.
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B. Need for Regulatory Action
In January 2023, the EPA issued a final rule titled ``Control of
Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle
Standards'' (the ``2023 Final Rule'').\2\ The 2023 Final Rule included
new, more stringent emission standards for oxides of nitrogen
(NOX), particulate matter (PM), hydrocarbons (HC), and
carbon monoxide (CO) for MY 2027s and later heavy-duty engines.\3\ The
2023 Final Rule also changed key provisions of the existing heavy-duty
engine emissions control program, including test procedures, regulatory
useful life, emission-related warranty, and other requirements.
Additionally, the 2023 Final Rule included changes to maintenance and
serviceability, including newly codified SCR inducement provisions.
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\2\ 88 FR 4296 (Jan. 24, 2023).
\3\ The EPA refers to NOX, PM, HC, CO, volatile
organic compounds (VOC), and sulfur dioxide more generally as
``criteria pollutants'' throughout this preamble.
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Immediately upon taking office, President Trump established new
Executive Branch priorities for energy, transportation, and consumer
choice and committed to ensuring regulations remain within
constitutional and statutory bounds. On March 12, 2025, the EPA
Administrator announced that the Agency would reevaluate the 2023 Final
Rule as part of the deregulatory actions the Agency would undertake.\4\
Following this announcement, the EPA heard concerns from truck and
engine manufacturers, the component supply industry, as well as truck
users, trucking fleets, and truck dealerships, about the expected cost
increases associated with the 2023 Final Rule's changes to the
emission-related warranty and regulatory useful life periods (the
Agency also received comments from a number of these stakeholders
raising concerns with the potential high costs
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during the development of the 2023 Final Rule). In addition, several
engine manufacturers have expressed concerns with the increased useful
life which is set to begin in MY 2027 and the increased risk of non-
compliance for in-use engines over their extended regulatory useful
life. The EPA has also identified several areas where amending specific
test procedures and other compliance provisions could support
implementation of the MY 2027 program.
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\4\ U.S. Environmental Protection Agency. (2025). ``EPA Launches
Biggest Deregulatory Action in U.S. History''. https://www.epa.gov/newsreleases/epa-launches-biggest-deregulatory-action-us-history.
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On August 12, 2025, the Administrator also stated the EPA's
intention to further improve operator experience with diesel engines
using SCR systems, including assessing whether engine performance
derates may no longer be necessary to ensure the proper use of diesel
exhaust fluid (DEF).\5\ After this announcement, individual operators
and States, such as Iowa, Alaska, and Nebraska, expressed concerns with
inducements, and a bill was brought to Congress regarding relief for
inducements in prolonged cold weather.\6\ In response to feedback and
concerns that the EPA continues to receive regarding the impact of
inducements, the Agency is revisiting the inducement regulations
finalized in the 2023 Final Rule for new heavy-duty highway engines.
This includes revisiting how restrictive inducements should be to
provide a reasonable basis for demonstrating that operators would
continue to add quality DEF in tanks and not tamper with SCR systems.
The EPA is also considering what changes could apply to in-use highway
engines and vehicles and nonroad engines currently covered under
existing EPA guidance.
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\5\ U.S. Environmental Protection Agency. (2025). ``At Iowa
State Fair, EPA Administrator Zeldin Announces Diesel Exhaust Fluid
(DEF) Fix.'' https://www.epa.gov/newsreleases/iowa-state-fair-epa-administrator-zeldin-announces-diesel-exhaust-fluid-def-fix.
\6\ See, e.g., Office of the Nebraska Attorney General (2026).
``Nebraska Attorney General's Office Issues Safety Alert Regarding
Diesel Exhaust Fluid (DEF) System Failures Affecting Farmers,
Truckers, and Motorists.'' https://ago.nebraska.gov/nebraska-attorney-generals-office-issues-safety-alert-regarding-diesel-exhaust-fluid-def-system.
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Finally, the EPA is aware that some manufacturers' MY 2027 medium
and heavy heavy-duty engine development programs have experienced
technical challenges, and a few diesel engine models/families are at
risk of not being completed in time for a January 2027 introduction.
Consequently, these manufacturers have requested, and the EPA is
proposing, NCPs under CAA section 206(g), which would allow these
manufacturers to continue to sell their current products while they
complete the development of engines compliant with the MY 2027
standards.
C. Summary of the Major Provisions in This Proposal
Truck and engine manufacturers as well as the component supply
industry have been preparing for several years to meet the MYs 2027 and
later NOX, PM, HC, and CO standards and other requirements
finalized in the 2023 Final Rule. Over the past year, most truck and
engine manufacturers have communicated to the EPA that they will have a
full lineup of products ready to meet the MY 2027 standards. However,
some truck and engine manufacturers and the broader industry, including
trucking fleets and dealers, have raised concerns with the overall
costs of new vehicles resulting from the 2023 Final Rule. In light of
concerns from truck and engine manufacturers, the component supply
industry, and truck users, trucking fleets, and truck dealerships, the
EPA is proposing targeted revisions to certain program elements that
are expected to reduce the program costs, while limiting the impact on
engine and vehicle manufacturers' significant investments and plans for
providing compliant MY 2027 products, and retaining the majority of the
projected emissions reductions from the 2023 Final Rule.
In the 2023 Final Rule, the projected costs due to the lengthened
emission-related warranty periods were the largest individual
contributor to the EPA's projected per-vehicle cost increases, and
total program costs. As described in section III.A of this preamble,
the EPA is now reconsidering whether the long-term emission reductions
projected for longer emission-related warranty periods and the
justifications presented in the 2023 Final Rule are reasonable. In
consideration of the cost impacts, potential increased purchase price
and reduced emission-related warranty coverage options for purchasers,
and the associated relatively small emissions impact, the EPA proposes
to retain the MY 2026 emission-related warranty periods for MYs 2027
and later heavy-duty engines.
The 2023 Final Rule also lengthened the useful life periods for all
heavy-duty engine regulatory classes. The new useful life periods
require manufacturers to demonstrate at the time of certification that
the emission controls on their MYs 2027 and later engines are durable
over the longer periods, and manufacturers are responsible for ensuring
that their engines will meet the standards in-use during those useful
life periods. In meetings with manufacturers over the past year about
their readiness for the MY 2027 program, several manufacturers have
noted they can meet the initial certification requirements but
expressed concern with the uncertainty of in-use performance of their
new technologies over the full useful life for the range of vehicle
applications. Based on their technology development work since January
2023, these manufacturers suggest that a shorter useful life would give
them more time to evaluate their new technologies in the real world and
build more confidence in their ability to meet the MY 2027 standards
in-use over the longer useful life periods. As described in section
III.B of this preamble, the EPA proposes that the longer useful life
periods would apply beginning in MY 2030. This proposed implementation
delay is intended to mitigate manufacturer concerns regarding
compliance uncertainties for the extended period over which
manufacturers have limited data and provide manufacturers with
additional lead time to refine emission control systems before the
engines are subject to the longer regulatory useful life.
[[Page 43158]]
The EPA is also proposing to establish NCPs for certain categories
of compression-ignition heavy-duty engines. Under CAA section 206(g), a
manufacturer is allowed to produce engines that do not meet the
applicable standards ``if such manufacturer pays a nonconformance
penalty as provided under regulations promulgated by the Administrator
after notice and opportunity for public hearing.'' \7\ Under existing
EPA regulations, the EPA would establish NCPs if three criteria are
met: (1) The emission standard in question becomes more difficult to
meet; (2) Substantial work must be required to meet the emission
standard; and (3) the Agency finds that a manufacturer is likely to be
noncomplying for technological reasons (referred to in earlier rules as
a ``technological laggard''). The EPA believes these criteria have been
met for the MY 2027 NOX standards for diesel-fueled engines
in the Medium HDE and Heavy HDE regulatory categories and is proposing
to establish NCPs for these engine categories as described in section
IV of this preamble.
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\7\ 42 U.S.C. 7525(g).
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Finally, in the 2023 Final Rule, the EPA codified regulatory
requirements to address how manufacturers can certify engines that use
DEF in SCR aftertreatment systems. The 2023 Final Rule mandated
manufacturers to initiate an engine performance derate, or inducement,
to address concerns with DEF quality, DEF supply, and tampering. As
described in section V of this preamble, continued operator frustration
has motivated the EPA to reassess the Agency's approach to certifying
SCR-equipped engines. In this action, the EPA is proposing to replace
engine performance derates as a part of SCR-related inducement
provisions with visible and/or audible notifications. These proposed
amendments for inducements would apply to newly manufactured highway
engines and vehicles (i.e., light- and medium-duty vehicles and heavy-
duty engines) and in nonroad applications. Under CAA sections 202 and
213, the EPA sets and implements emission standards for new highway and
nonroad engines and vehicles throughout their useful life; however, the
EPA will be considering new inducement guidance for in-use highway and
nonroad diesel engines and vehicles regarding ongoing compliance with
such regulations. The EPA is considering whether such guidance might
provide recommendations for engine manufacturers to get approval to
modify in-use engines, consistent with any provisions the EPA adopts in
this rulemaking, without violating prohibitions against tampering and
defeat devices.
D. Summary of the Impacts of This Proposal
The EPA updated costs from the 2023 Final Rule Regulatory Impact
Analysis (RIA) to reflect the projected change in emission-related
warranty costs and operating costs associated with this proposed
action. There are no changes to direct manufacturing costs between the
proposed action case and the no-action case. The EPA understands that
manufacturers have already solidified their technology designs for MY
2027 engines, and the Agency believes that manufacturers are likely to
maintain a steady design technology for MY 2028 and 2029 and will not
redesign engines in response to the proposed shorter useful life
periods for those model years.
As shown in Table I-1, and in more detail in section VI of this
preamble, engine manufacturers would see cost savings due to the
proposed shorter emission-related warranty period per engine for MY
2027 by regulatory class and fuel type and those savings are likely to
be passed on to the vehicle purchaser. See section VI of this preamble
and Chapter 3 of the Draft Regulatory Impact Analysis (DRIA) for
additional information on the cost impacts of this proposal.\8\ The EPA
expects that manufacturers will pass these savings on to purchasers.
Thus, the EPA expects purchasers to save up to $37 billion in emission-
related warranty savings, including up to $6,000 per diesel vehicle
from the warranty savings alone (see Table I-2). Purchasers would also
incur additional operating costs, but net cost savings could be as high
as $12 billion.
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\8\ U.S. Environmental Protection Agency. ``Amendments and
Nonconformance Penalties for Model Year 2027 and Later Heavy-Duty
Highway Engines and Amendments to Inducement Provisions for SCR-
Equipped Diesel Engines: Draft Regulatory Impact Analysis.'' July
2026. EPA-420-D-26-002.
[GRAPHIC] [TIFF OMITTED] TP14JY26.001
[[Page 43159]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.002
In section VII of this preamble, the EPA presents the combined
emissions impacts of the proposed revisions in calendar years 2030,
2040, 2045, and 2055,\9\ which are summarized in Table I-3.
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\9\ The 2023 Final Rule inventory analysis included calendar
years up to 2045. For this proposed rule, the EPA extended analysis
years to 2055 to better reflect the impact of fleet turnover further
into the future.
[GRAPHIC] [TIFF OMITTED] TP14JY26.003
The EPA estimates that the 2023 Final Rule, as amended by this
proposal, would continue to reduce the onroad heavy-duty NOX
inventory in 2055 by about 42 percent--over 260,000 tons of
NOX--compared to the 2055 heavy-duty NOX
inventory without the 2023 Final Rule. The proposed amendments would
retain nearly 90 percent of the NOX reductions originally
projected to result from the 2023 Final Rule because the more stringent
standards and more representative test cycles finalized in the 2023
Final Rule remain in place.
II. Introduction
A. Background
In January 2023, EPA adopted the 2023 Final Rule, which included
new, more stringent emission standards for NOX, PM, HC, and
CO for MYs 2027 and later heavy-duty highway engines.\10\ The 2023
Final Rule also changed key provisions of the existing heavy-duty
emissions control program, including test procedures, regulatory useful
life, emission-related warranty, and other requirements. Additionally,
the 2023 Final Rule included changes to maintenance, serviceability,
and certain inducement provisions.
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\10\ 88 FR 4296 (Jan. 24, 2023).
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B. Response to the 2023 Final Rule
On March 12, 2025, the EPA Administrator announced that the Agency
would reevaluate the 2023 Final Rule.\11\ Following this announcement,
the EPA heard concerns from truck and engine manufacturers, the
component supply industry, and truck users, trucking fleets, and truck
dealerships, about the expected cost increases associated with the 2023
Final Rule's changes to the emission-related warranty and regulatory
useful life periods (the Agency also received comments from a number of
these stakeholders raising concerns with the potential high costs
during the development of the 2023 Final Rule). The EPA has also
identified several areas where amending specific test procedures and
other compliance provisions could support the implementation of the MY
2027 program.
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\11\ U.S. Environmental Protection Agency. (2025). ``EPA
Launches Biggest Deregulatory Action in U.S. History.'' https://www.epa.gov/newsreleases/epa-launches-biggest-deregulatory-action-us-history.
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Since the 2023 Final Rule was finalized, truck and engine
manufacturers as well as the component supply industry have been
preparing to meet the MYs 2027 and later NOX, PM, HC, and CO
standards and other requirements. Over the past year, most truck and
engine manufacturers have communicated to the EPA that they will have a
full lineup of products ready to meet the MY 2027 standards. However,
some truck and engine manufacturers and the broader industry, including
trucking fleets and dealers, have raised concerns with the overall
costs of new vehicles resulting from the 2023 Final Rule.
In the 2023 Final Rule, the EPA projected that up to 50 percent of
the program costs can be attributed to the longer emission-related
warranty periods.\12\ Considering that the length of the emission-
related warranty period does not factor into the stringency or
feasibility of the standards and would not impact engine manufacturer's
investments and production plans, the EPA considers a reduction in the
emission-related warranty periods to be a straightforward cost-saving
opportunity for engine manufacturers, truck dealerships, and trucking
fleets regarding the potential purchase price increases due to the
longer emission-related warranty periods.
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\12\ See the indirect cost calculations presented in Chapter
7.1.2 of the 2023 Final Rule RIA. Control of Air Pollution from New
Motor Vehicles: Heavy-Duty Engine and Vehicle Standards Regulatory
Impact Analysis. December 2022. EPA-420-R-22-035.
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[[Page 43160]]
In preparation for meeting the longer useful life periods
promulgated under the 2023 Final Rule, most manufacturers have
successfully initiated durability testing for MY 2027 certification,
which is used to demonstrate that their engines maintain emission
performance and meet the standards through the full useful life.
However, several manufacturers have expressed concern with increased
in-use compliance risk of the longer useful life periods established in
the 2023 Final Rule. These manufacturers have noted that they are
confident in the performance of their chosen technology pathway to meet
the MY 2027 standards over the longer useful life in the laboratory,
but they are less certain about how the technology will perform over
the longer periods in real-world operation.
Some engine manufacturers have also expressed concerns with the MY
2027 longer useful life as it impacts the near-term use of
NOX emission credits under the EPA's averaging, banking, and
trading (ABT) program. Relative to credits generated using pre-MY 2027
useful life periods, manufacturers would have to use more credits to
apply them to MYs 2027 and later engines, which would accelerate
depletion of their credit banks. This accelerated depletion can be
especially challenging as manufacturers transition to more stringent
standards under a compliance program that also includes new test
procedures and other requirements.
In the 2023 Final Rule, the EPA recognized that low-volume
specialized vocational vehicles, such as fire trucks, refuse trucks,
concrete mixers, emergency vehicles, heavy-haul tractors, and custom-
chassis motor homes, can require more extensive redesign to integrate
aftertreatment systems needed to meet the MY 2027 standards. In
response to concerns that manufacturers needed additional lead time for
certain low-volume products, the EPA finalized an interim provision for
MYs 2027 through 2029 that allows manufacturers to use NOX
emission credits generated under the existing ABT program to certify up
to five percent of their production volume of Heavy HDE compliant at
pre-MY 2027 requirements.\13\ As manufacturers considered how to apply
this five percent production volume allowance for their products, the
EPA heard from some manufacturers that they have engines intended for
low-volume specialty vehicles, such as refuse trucks, urban buses,
motorcoaches, and fire trucks, that would qualify for this allowance,
but they do not have sufficient NOX credit balances to use
the existing flexibility.
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\13\ Specifically, this allowance is limited to five percent of
a manufacturer's U.S.-directed production volume of Heavy HDE from
MYs 2023 through 2025.
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The EPA notes that most engine manufacturers are on track to meet
the MY 2027 standards. The EPA acknowledges that there was substantial
work required to meet these standards, including implementing new
technologies and demonstrating compliance with new test procedures.\14\
The technologies manufacturers have chosen for this program range from
specific upgrades to the existing emissions control technologies to
more comprehensive upgrades that coincide with the development and
launch of entirely new engine platforms. The EPA is aware that some
manufacturers' MY 2027 Medium HDE and Heavy HDE development programs
have experienced technical challenges, and that some diesel engine
families are at risk of not being completed in time for a January 2027
introduction (see section IV.A of this preamble). Consequently, these
manufacturers have requested that the EPA establish NCPs under CAA
section 206(g), which would allow them to continue to sell their
current products while they complete the development of the engines
compliant with the MY 2027 standards. The EPA is therefore proposing to
establish NCPs for diesel-fueled Medium HDE and Heavy HDE for the MY
2027 NOX standards.
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\14\ The EPA is not reopening MYs 2027 and later test procedures
except in the limited ways specifically proposed in section III.E of
this preamble, regarding targeted technical amendments to correct or
add clarification.
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The 2023 Final Rule mandated manufacturers to initiate an engine
performance derate, or inducement, to address concerns with DEF
quality, DEF supply, and tampering. On August 12, 2025, the
Administrator also stated the EPA's intention to further improve
operator experience with diesel engines using SCR systems, including
assessing whether engine performance derates may no longer be necessary
for compliance.\15\ In response to the Administrator's announcement and
feedback and concerns that the EPA continues to receive regarding the
impact of DEF inducements, the Agency began revisiting the questions
and principles discussed in the 2023 Final Rule, including how
restrictive inducements should be to provide a reasonable basis for
demonstrating that operators would continue to add quality DEF in tanks
and not tamper with SCR systems.
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\15\ U.S. Environmental Protection Agency. (2025). ``At Iowa
State Fair, EPA Administrator Zeldin Announces Diesel Exhaust Fluid
(DEF) Fix.'' https://www.epa.gov/newsreleases/iowa-state-fair-epa-administrator-zeldin-announces-diesel-exhaust-fluid-def-fix.
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In addition to the emission-related warranty, useful life,
production allowance, and inducement elements from the 2023 Final Rule,
the EPA, manufacturers, and other stakeholders have identified several
areas where amending the specific test procedures and other compliance
provisions could improve the overall accuracy, repeatability, and
clarity of the regulations without changing the stringency of the
standards.
C. Summary of the Proposal
As noted previously, most engine manufacturers are on track to meet
the MY 2027 standards. Therefore, the EPA is not reopening the MYs 2027
and later NOX, PM, HC, and CO standards in this rulemaking.
The EPA is proposing targeted revisions to the emission-related
warranty, the regulatory useful life, and the five percent production
volume allowance finalized in the 2023 Final Rule. These revisions are
intended to reduce costs that could otherwise be passed on to customers
as increased purchase prices. In section III.A of this preamble, the
EPA describes the Agency's proposal to shorten the emission-related
warranty periods for MY 2027s and later engines to the values that
apply to MY 2026 and earlier engines. In section III.B of this
preamble, the EPA also proposes to delay implementation of the MYs 2027
and later engines' useful life periods to instead start in MY 2030. As
such, the current MY 2026 and earlier useful life periods would
continue to apply through MY 2029. As described in section III.C of
this preamble, the EPA is continuing the existing allowance for
manufacturers to produce up to five percent of their U.S.-directed
production volume of Heavy HDE that is compliant with pre-2027
requirements, but proposes to remove the requirement to use
NOX credits. These targeted revisions are expected to reduce
the program costs (see section VI of this preamble), while limiting the
impact on manufacturers' current production plans and retaining the
majority of the projected emissions reductions from the 2023 Final Rule
(see section VII.B of this preamble).
As described in section IV of this preamble, the EPA is also
proposing to establish NCPs for certain categories of compression-
ignition heavy-duty engines. Specifically, the EPA proposes NCPs for
the Medium HDE and Heavy HDE categories.
[[Page 43161]]
The EPA is also proposing to replace engine performance derates for
SCR-related inducements with visible and/or audible notifications.
These new inducement provisions would apply to new heavy-duty highway
engines as well as new light-duty and medium-duty vehicles and nonroad
diesel engines (see section V of this preamble).
Finally, as described in section III.E of this preamble, the EPA
has also identified several additional amendments that would improve
the heavy-duty engine programs.\16\ The EPA is proposing specific
targeted amendments to correct or add clarification to several test
procedures, including the deterioration factor procedure for durability
testing, the in-use moving average window procedure for off-cycle
testing, the optional engine idle procedure, and the vanadium
sublimation procedure for vanadium-based catalyst systems. The EPA is
proposing amendments to align the heavy-duty powertrain testing and PM
background correction procedures with the light-duty vehicle procedures
to limit test burden for manufacturers that certify both light- and
heavy-duty products. The EPA is proposing an amendment to extend an
allowance for a limited number of qualifying hybrid specialty vehicles
to use engines certified to alternative emission standards until MY
2030 under certain conditions. The EPA is also proposing targeted
amendments to the onboard diagnostic system requirements that are
intended to improve user experiences with MYs 2027 and later emission
controls.
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\16\ It is important to note that while this proposed rule
includes a range of specific, targeted amendments to the
regulations, the EPA is otherwise not reopening those provisions and
is neither proposing nor seeking comment on the underlying standards
or program requirements.
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D. Legal Authority
Statutory authority for this proposed action comes from the CAA (42
U.S.C. 7401-7675). In this proposed action, the EPA is proposing to
amend the emission-related warranty, regulatory useful life, and
certain other provisions for MYs 2027 and later heavy-duty engines
under CAA sections 202, 203, 206, 207, and 216. Unless provided
otherwise by statute, an agency may revise or rescind prior actions so
long as it acknowledges the change in position, provides a reasonable
explanation for the new position, and considers legitimate reliance
interests in the prior position.\17\
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\17\ See FDA v. Wages & White Lion Invs., L.L.C., 604 U.S. 542
(2025); FCC v. Fox Television Stations, Inc., 556 U.S. 502 (2009);
Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463
U.S. 29 (1983); Clean Air Council v. Pruitt, 862 F.3d 1, 8 (D.C.
Cir. 2017) (``Agencies obviously have broad discretion to reconsider
regulations at any time'').
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E. Reliance Interests
The EPA understands that companies have previously planned for the
MY 2027 start date for the MYs 2027 and later heavy-duty engine
emission standards and related program requirements.
The EPA acknowledges that this proposal would, if finalized, change
the Agency's previous assessments in the 2023 Final Rule with respect
to the emission-related warranty, regulatory useful life, and other
program elements. The EPA notes that this proposal does not change the
emission standards and related test cycles established in the 2023
Final Rule for MY 2027 and later. As explained throughout this
preamble, the EPA believes this change in position is necessary. The
EPA believes that the revisions proposed in this action relieve
obligations in a manner that promotes compliance and cost savings
without undermining existing investments in compliance. Nevertheless,
the EPA requests comment on whether regulated parties have any
significant reliance interests with respect to the changes in emission-
related warranty, regulatory useful life, and other program elements
contained in this proposal. (C-1).
The EPA further understands that other interested parties may have
relied on the MY 2027 heavy-duty program for independent purposes,
including compliance with relevant National Ambient Air Quality
Standards (NAAQS) and related planning obligations, among others. The
EPA believes that the relatively small foregone emissions reductions
involved in this proposed revision, coupled with the relatively short
amount of time that has passed since promulgation of the 2023 Final
Rule, means that such interests do not supersede the Agency's
obligation to ensure that program elements are appropriate and reflect
technical and market realities. Moreover, the EPA notes that emissions
from mobile sources are just one consideration among many involved in
planning to attain the NAAQS and related obligations. Nevertheless, the
EPA requests comment on such reliance interests and how such interests
should be taken into account in any final action on this proposal. (C-
2).
The EPA requests comment on the nature and extent of any other
reliance interests that may arise from this proposed action and is
committed to assessing any such interests, determining whether they are
significant, and weighing such interests against competing rationales,
as required by law. (C-3).
III. Proposed Compliance Provisions and Test Procedures
The EPA is proposing targeted revisions to the 2023 Final Rule to
aid in the implementation of the MYs 2027 and later HD engine criteria
pollutant emissions program, reduce the cost of the program, and
improve operator experiences. The proposed changes include continuing
the MY 2026 and earlier emission-related warranty periods for MYs 2027
and later engines, delaying the implementation of the MY 2027 useful
life periods by three years, and targeted revisions to ABT credit
flexibilities. The EPA is also proposing discrete revisions to correct
and/or clarify certain identified regulatory provisions. This section
III describes the proposed revisions.
A. Emission-Related Warranty
The emission-related warranty period is the period over which CAA
section 207 requires an engine manufacturer to warrant to a purchaser
that: (1) the engine is designed, built, and equipped so as to conform
with applicable regulations under CAA section 202 and (2) is free from
defects in materials or workmanship which would cause the engine not to
conform with applicable regulations for the warranty period. If an
emission-related component fails during the regulatory emission-related
warranty period, the manufacturer is required to pay for the cost of
repair or replacement. A manufacturer's general emission-related
warranty responsibilities are currently set out in 40 CFR 1068.115.
Note that while an emission-related warranty provides protection to the
owner against emission-related repair costs during the warranty period,
the owner is responsible for properly maintaining the engine (40 CFR
1068.110(e)), and the manufacturer may deny warranty claims for
failures caused by the owner's or operator's improper maintenance or
use (40 CFR 1068.115(a)).
In the 2023 Final Rule, the EPA finalized increases in the
emission-related warranty periods for MYs 2027 and later engines, as
shown in Table III-1, which relied on three primary justifications.\18\
First, the EPA expected longer emission-related warranty periods would
lead owners to continue to maintain their engines and vehicles over a
longer period of time, which would ensure longer-term benefits of
emission controls. Second, the EPA
[[Page 43162]]
noted that manufacturers may be more incentivized to simplify complex
components to reduce in-use failures if they were responsible for
repairs over longer periods. Finally, the EPA projected that longer
warranty periods would allow manufacturers to have access to better
defect information over a period of time more consistent with engine
useful life. Manufacturers are currently required to track and report
defects to the EPA under the defect reporting provisions of 40 CFR part
1068. Under 40 CFR 1068.501(b), manufacturers investigate possible
defects whenever a warranty claim is submitted for a component and can
monitor defect information from dealers and repair shops that perform
those warranty repair services. After the emission-related warranty
period ends, a manufacturer would not necessarily know about these
defects, since repair facilities are less likely to be in contact with
the manufacturers and less likely to use original equipment
manufacturer (OEM) parts.
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\18\ 88 FR at 4364.
[GRAPHIC] [TIFF OMITTED] TP14JY26.004
The EPA is reconsidering the longer emission-related warranty
periods in light of new information on costs and potential impact on
purchase price. The EPA proposes that the relatively small long-term
emission reductions projected for longer emission-related warranty
periods (see section VII of this preamble) and the uncertain long-term
improvements to component quality and serviceability that the Agency
previously used to justify the longer warranty periods do not outweigh
the costs and potential impact on purchase price.
The 2023 Final Rule estimated the increased emission-related
warranty costs per year for the vehicle regulatory classes represented
in EPA's Motor Vehicle Emission Simulator (MOVES) model,\19\ which
generally match the primary intended service classes of vehicles in
EPA's regulations. The EPA also estimated the age at which the range of
MOVES heavy-duty vehicle regulatory classes would reach their emission-
related warranty limit based on their projected mileage
accumulation.\20\
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\19\ The EPA inventory analysis for this proposal was performed
using a regulatory version of the Agency's MOVES model, known as
MOVES5.R2, which was derived from the latest public version (MOVES5)
with the updates described in Chapter 2.2 of the DRIA for this
proposed rule.
\20\ These costs were presented in Tables 7-14 through 7-17 of
the 2023 Final Rule RIA. See Control of Air Pollution from New Motor
Vehicles: Heavy-Duty Engine and Vehicle Standards, Regulatory Impact
Analysis. December 2022. EPA-420-R-22-035.
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In the 2023 Final Rule, the EPA projected significant
NOX emission reductions in calendar year 2045 from vehicles
subject to the MYs 2027 and later standards and other requirements.\21\
The NOX emission reductions attributable to the lengthened
emission-related warranty periods were relatively small compared to the
reductions due to the more stringent standards and more representative
test cycles also finalized under that program. While the EPA did not
separately present the contributions from each program element in the
2023 Final Rule, the Agency is updating the analysis in this proposed
rule to include the contributions of the program elements we are
proposing to revise (see section VII of this preamble). By removing the
longer emission-related warranty periods, the EPA projects
NOX emissions would increase by approximately 36,000 tons in
calendar year 2055. In the same year, the EPA estimates that the
remainder of the 2023 Final Rule program is projected to reduce
NOX emissions by approximately 260,000 tons relative to the
standards and requirements in place for MY 2026 and earlier engines.
The proposed changes to emission-related warranty periods would reduce
the NOX emission benefits estimated in the 2023 Final Rule
by 12 percent in calendar year 2055.
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\21\ See Table VI-1 of the 2023 Final Rule (88 FR 4418, Jan. 24,
2023).
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In response to the new emission standards for the MY 2027 program,
manufacturers have added technology that qualifies as emission-related
components covered under warranty. For any new emission-related
components, manufacturers project purchase price adjustments to cover
anticipated warranty costs, which would have resulted in a higher
warranty cost pursuant to the 2023 Final Rule. By lengthening emission-
related warranty periods in addition to adopting new emission standards
for the MY 2027 program, the 2023 Final Rule has required manufacturers
to adjust their MYs 2027 and later warranty costs to cover the new
technology, as well as costs to cover the emission-related components
already on their engines for longer coverage periods.
In the 2023 Final Rule, emission-related warranty costs were the
largest individual contributor to the per-vehicle cost increases and
the total program costs. Since the 2023 Final Rule, the EPA has met
with manufacturers and has learned that the emission-related warranty
costs could be significantly higher for certain applications. In the
case of the Heavy HDE category, OEMs have shared that the cost increase
for just the emission-related warranty could exceed $15,000 for some
engines intended for use in low-mileage vocational vehicles for which
the engine would be covered by warranty until the 10 year limit.\22\
Commenters on the proposal to the 2023 Final Rule, including engine
manufacturers, suppliers, purchasers, and industry trade associations,
stated that emission-related warranty costs are generally passed on to
customers in the vehicle purchase price, and they noted that such an
increase could impact vehicle sales.\23\
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\22\ This is consistent with the 2023 Final Rule emission-
related warranty cost analysis that estimated warranty costs are
approximately $1,000 per year.
\23\ See sections 4 and 25 of the EPA's summary and response to
comments on the proposal to the 2023 Final Rule. ``Control of Air
Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle
Standards Response to Comments.'' EPA-420-R-22-036. December 2022.
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[[Page 43163]]
Longer emission-related warranties may not align with the
preferences or usage patterns of all purchasers. In comments on the
proposal to the 2023 Final Rule, American Trucking Associations (ATA)
noted that certain fleets purchase extended warranties based upon the
unique business models and financial means of each company.\24\ ATA
stated that fleets with short turnover cycles for their vehicles should
not be required to purchase warranties that exceed their mileage needs
and that such a requirement may have the unintended consequence of some
fleets retaining their current trucks longer. In response to this
comment in the 2023 Final Rule, the EPA noted that, to the extent that
fleets currently base their shorter turnover cycle on the EPA emission-
related warranty periods, the Agency expected those fleets to consider
adjusting their current business model to accommodate the longer
warranties in the 2023 Final Rule.\25\ In reconsidering the longer
emission-related warranty periods, the EPA acknowledges that the
shorter, pre-2026 warranty periods would allow these companies to
continue to opt for additional warranty coverage if it meets their
specific operational requirements, which would reduce the influence of
the warranty as a factor a business might consider when deciding
whether to purchase a new vehicle.\26\
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\24\ Comments of the American Trucking Associations: On the
Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine
and Vehicle Standards Proposed Rule. EPA-HQ-OAR-2019-0055-1326-A1.
Pages 11-17.
\25\ See section 18.3 of the EPA's summary and response to
comments on the proposal to the 2023 Final Rule. ``Control of Air
Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle
Standards Response to Comments.'' December 2022. EPA-420-R-22-036.
p. 1147.
\26\ While the required emission-related warranty period for
manufacturers is proposed to be shortened, the post-warranty period
for which owners would be responsible for emission-related repairs
would be lengthened. The increased emission-related repair costs
associated with the proposed warranty periods are reflected in the
operating costs of the EPA's cost analysis. See Chapter 3 of the
DRIA for this proposed rule.
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In consideration of the cost impacts, potential increased purchase
price and reduced warranty coverage options for purchasers, and the
associated, relatively small emissions impact compared to the full
scope of the 2023 Final Rule, the EPA proposes to retain the MY 2026
emission-related warranty periods for MYs 2027 and later. This proposal
is based on the recognition that maintaining the much longer emission-
related warranty for MYs 2027 and later will significantly increase the
manufacturer costs and consumer prices for a relatively small emissions
benefit. The EPA believes that the emission-related warranty periods in
place for MY 2026 and earlier engines would continue to ensure that the
regulated industry would design and warrant robust emission control
technologies while allowing commercial truck purchasers to make their
own decisions on the need to purchase extended warranties (which many
purchasers do today).
B. Regulatory Useful Life Periods
Useful life represents the period over which emission standards
apply to certified engines, and, practically, any difference between
the regulatory useful life and the generally longer operational life of
in-use engines represents miles and years of operation without an
assurance that emission standards will continue to be met. For the
EPA's heavy-duty highway engine program, useful life periods vary by
engine class to reflect the different lengths of their estimated
operational lives. As described in the 2023 Final Rule, the EPA
considers operational life to be the average mileage at rebuild for
compression-ignition engines (i.e., engines typically fueled by diesel
or natural gas) and the average mileage at replacement for spark-
ignition engines (i.e., engines typically fueled by gasoline or
liquefied petroleum gas).
[GRAPHIC] [TIFF OMITTED] TP14JY26.005
The MYs 2026 and earlier useful life periods have been in place
since 2004, and manufacturers have had decades to refine their
durability demonstrations and understand the in-use durability of their
emission controls over those periods. The new useful life periods
require manufacturers to demonstrate at the time of certification that
the emission controls on their MYs 2027 and later engines are durable
over the longer periods. Additionally, the new emission standards,
which the EPA is not reopening in this proposed rule, will apply to the
applicable useful life periods, and manufacturers are responsible for
ensuring that their engines will meet the standards in-use over those
useful life periods.
The EPA included flexibilities in the 2023 Final Rule to limit
additional certification test burden and in-use uncertainty due to the
longer useful life periods. The EPA finalized a new durability test
procedure that allows manufacturers to accelerate the aging of their
emission controls to capture the additional time without a
proportionally increased test burden. Manufacturers are actively
applying the accelerated aging procedures for their MY 2027 engine
certification and the EPA continues to receive data on those
activities.\27\ In terms of in-use uncertainty, the EPA finalized a 15
milligrams per brake horsepower-hour (mg/hp[middot]hr) in-use
compliance margin for Medium HDE and Heavy HDE for in-use testing of
engines to the laboratory-based duty cycles and off-cycle test
procedures,\28\ and also added an accuracy margin to address
uncertainty in the portable emissions measurement equipment used for
onroad in-use testing.\29\
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\27\ In section III.E.1 of this preamble, the EPA proposes
clarifications and corrections resulting from EPA and manufacturer
experiences in applying these new procedures.
\28\ 88 FR 4334.
\29\ 88 FR 4353.
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In meetings with manufacturers over the past year about their
readiness for the MY 2027 program, some
[[Page 43164]]
manufacturers have indicated that they are on target to meet the
requirements of the longer useful life periods, including in-use
performance. Other manufacturers noted they can potentially meet the
certification requirements but expressed concern with the uncertainty
of in-use performance of their new technologies over the full useful
life for the range of vehicle applications. Manufacturers suggest that
a shorter useful life would give them more time to evaluate their new
technologies in the real world and more confidence in the in-use
durability over the longer useful life periods.
In response to industry feedback and the credible information
shared about their technological readiness, the EPA proposes a three-
year delay in the implementation of the increased useful life periods
for heavy-duty engines shown in Table III-2. Specifically, the EPA
proposes that the new useful life periods would apply beginning in MY
2030. This proposed implementation delay is intended to mitigate
manufacturer concerns regarding compliance uncertainties for the
extended period over which manufacturers have limited data and provide
manufacturers with additional lead time to refine emission control
systems before the engines are subject to the longer regulatory useful
life.
Delaying the longer regulatory useful life periods would provide
heavy-duty engine manufacturers with time to collect durability data on
their in-use engines with the new technologies without having to manage
the risks and burdens of a potential engine recall due to exceeding the
emission standards during the longer useful life periods. Manufacturers
have spent four or more years developing and testing engines, both in
the laboratory and in vehicles with their low volume pre-production
engines, to ensure that their engines will be durable and able to meet
the standards for the longer useful life. However, since this
development has been limited to pre-production engines, no company has
real-world data on MY 2027 production hardware over the range of
applications in which these engines may be used. Manufacturers have
thorough development processes to test their products under conditions
that reflect some of the most challenging real-world operations, and
there is additional experience which will be gained with production
engines in the real-world with the diversity of the engines'
applications. Under the proposed delay of the longer regulatory useful
life periods to MY 2030, manufacturers will be able to gain this real-
world, in-use experience through three years of production engines
subject to the MY 2027 standards. The proposed delay would provide
additional lead time during which manufacturers can refine their
engines and emission controls over the expanded operating conditions
covered in the MYs 2027 and later program at the current useful life
periods. This is intended to increase manufacturers' confidence that
their products will comply with the standards for the duration of the
longer useful life periods.
As shown in section VII of this preamble and Chapter 2 of the DRIA
for this proposed rule, the EPA projects that the proposed delay in the
lengthened useful life periods would have a minimal impact on the
emissions inventory. To estimate the emissions inventory impacts, the
EPA applied the shorter useful life periods for MY 2027 through MY
2029. The EPA believes this approach to estimating emissions impacts is
conservative, because the timing of this proposed rule may limit the
changes manufacturers would be willing to make to their engines prior
to the start of production for MY 2027. The EPA expects most
manufacturers will likely produce the same engines they have been
preparing to manufacture for MY 2027; in fact, there is the potential
that more new vehicles will be available for sale that would increase
the probability that consumers will purchase newer vehicles that have a
better emissions profile relative to their existing vehicles. In
addition, because the proposal does not alter the emission standards,
manufacturers will be motivated to gain as much real-world experience
with the technology needed to meet the standards at the longer useful
life. Therefore, the EPA does not expect engines to be less durable
under this proposed change.
Based on discussions with individual engine manufacturers, the EPA
expects the manufacturers that are currently prepared to certify
engines meeting the longer useful life periods would equally benefit
from the longer lead time to design their engines to address any
uncertainties they may have regarding their in-use compliance. However,
the EPA recognizes that the Agency must consider, and correspondingly
propose to address, discrepancies that would result relating to
durability testing that manufacturers may have already completed at the
longer useful life periods. The EPA is proposing two methods under a
new interim provision in 40 CFR 1036.150, which would apply to MY 2027
through MY 2029, depending on whether the manufacturer included an
emissions test point at the useful life periods that apply to MYs 2026
and earlier (e.g., equivalent to 435,000 miles for Heavy HDE) or if
they only conducted the test to the full MYs 2027 and later useful life
(e.g., equivalent to 650,000 miles for Heavy HDE). If available, the
EPA is proposing under this interim provision that manufacturers must
use test data from the point that is equivalent to the useful life
periods that apply to MYs 2026 and earlier. If manufacturers did not
collect data at that point, the EPA would allow manufacturers to
interpolate their data to the shorter useful life periods that apply to
MYs 2026 and earlier using the data at the low-hour and longer useful
life test points. The EPA requests comment on this interim provision.
(C-4).
With this proposed change to useful life, there would likely be a
reduction in manufacturers' costs. As stated above, the EPA does not
expect manufacturers who have products ready for MY 2027 to change
their emissions control technology plans for the MYs 2027 through 2029
period because of this proposed change. However, manufacturers that
have not completed their durability demonstration for the longer useful
life may choose to stop the demonstration at the current useful life
values, which could result in a small reduction in testing costs that
manufacturers could pass on to their customers. For this proposal, the
EPA has taken a conservative approach to estimating the cost impacts of
the proposed change to useful life by projecting no change in costs.
The EPA requests comments on the cost savings from this provision. (C-
5). See section VI of this preamble and Chapter 3 of the DRIA for this
proposed rule for more details on the estimated cost impacts of the
proposed change to useful life.
Finally, the EPA notes that useful life also plays a role in
manufacturers' credit balances for those companies participating in the
ABT program.\30\ Useful life is a variable in the equation to calculate
NOX emission credits (see 40 CFR 1036.705(b)), and credits
earned and used are proportional to useful life. For example, unless a
manufacturer were to comply with the longer useful life periods early,
credit, earned from a 150 mg NOX/hp[middot]hr Heavy HDE in
MY 2022 to 2026 (i.e., 50 mg/hp[middot]hr below the standard) would be
generated using a useful life of 435,000 miles, and if the credits were
used to comply with an 65 mg NOX/hp[middot]hr Heavy HDE
(i.e., 30 mg/hp[middot]hr above the standard) for MY 2027, the credits
would be applied based on
[[Page 43165]]
a useful life of 650,000 miles. Therefore, for Heavy HDE, credits would
be used at a 1.49 times greater rate than earned for a useful life of
650,000 miles, for the same difference in mg of NOX per
hp[middot]hr between the Family Emission Limit (FEL) and the standard.
Delaying the increase in useful life periods will positively impact the
NOX credits manufacturers have accrued from selling MY 2022
and later engines that are over compliant with the pre-MY 2027
NOX standard. The resulting lower credit usage rate for MYs
2027 and later will allow manufacturers to extend the use of credits
already earned for a longer period and/or apply those credits to a
larger volume of engines during the transition to lower standards.
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\30\ See Chapter 1 of the DRIA for this proposed rule.
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In summary, the proposed delay for implementing the longer useful
life periods, and the associated reduction in credit usage that would
result, would afford manufacturers additional time to gain experience
with new technologies and test procedures that will begin to apply in
MY 2027. This additional time could allow for refining designs,
optimizing performance, and ensuring reliability under a wide range of
in-use operational conditions. Manufacturers could leverage this
extended lead time to conduct further testing and validation, ensuring
that innovations are not only compliant but also robust when the useful
life is increased in MY 2030 under the proposed delay. By proposing
this additional time, the EPA aims to balance the objectives of
stringent emission standards with pragmatic considerations of industry
readiness and corresponding uncertainties.
Finally, the EPA requests comment on indefinitely keeping the MY
2026 and earlier regulatory useful life periods for MYs 2027 and later.
(C-6). Chapter 2 of the DRIA for this proposed rule presents a scenario
that projects the emissions impacts of never extending the useful life
periods. For this scenario, the EPA has not estimated cost savings due
to changes in the emissions control technology. However, as discussed
in Chapter 3 of the DRIA for this proposed rule, the EPA would expect
manufacturers to change the design of the emissions controls if the
Agency were to finalize indefinitely keeping the MY 2026 and earlier
regulatory useful life periods for MYs 2027 and later. The EPA
understands stakeholders could potentially have concerns that products
meeting the longer useful life periods have not yet entered the market
and thus there is still some uncertainty in the feasibility of the
standards through the longer useful life periods for all real-world
applications.
C. Production Volume Allowance
In the 2023 Final Rule, the EPA adopted an interim production
volume allowance for MYs 2027 through 2029 in 40 CFR 1036.150(k) that
allows manufacturers to use NOX emission credits to certify
a limited volume of Heavy HDE compliant with pre-MY 2027
requirements.\31\ To aid in implementation, the EPA chose not to limit
the production volume allowance to specific applications of Heavy HDE
but did limit it to no more than five percent of the average U.S.-
directed production volumes of Heavy HDE over three MYs. In the 2023
Final Rule, the EPA noted that such an allowance from the MY 2027
criteria pollutant standards may be necessary to provide engine and
vehicle manufacturers with additional lead time and flexibility to
redesign some low-volume vehicles to accommodate the technologies
needed to meet the more stringent engine emission standards.
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\31\ Engines certified under this production volume allowance
would meet the pre-MY 2027 engine provisions of 40 CFR part 86,
subpart A.
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The EPA proposes to modify 40 CFR 1036.150(k) to not require the
use of NOX credits in MYs 2027 through 2029 for engines
certified under the interim production volume allowance. Under this
proposal, a manufacturer certifying up to five percent of its Heavy HDE
U.S.-directed production volumes under 40 CFR 1036.150(k) would not be
required to use NOX credits to offset the negative credits
associated with those engines. All other conditions of 40 CFR
1036.150(k) would remain in effect and the EPA is not proposing changes
to those provisions in this proposal, including the five percent cap
based on the MYs 2023 through 2025 U.S.-directed production volume
average, the limitation to Heavy HDE, certification to the MY 2026
requirements in 40 CFR part 86, subpart A, the carryover-family
requirement, declaration of a NOX FEL at or below the
standard set out in 40 CFR 86.007-11, and applicable reporting and
recordkeeping.
The EPA is proposing this change because the Agency has heard from
multiple engine manufacturers that they do not have sufficient
NOX credit balances to use the existing flexibility that was
designed to provide additional lead time for low-volume vehicles
applications that face unique engineering and packaging
constraints.\32\ Specialized vocational vehicles, such as fire trucks,
refuse trucks, concrete mixers, emergency vehicles, heavy-haul
tractors, urban buses, and custom-chassis motor homes can require more
extensive redesign to integrate aftertreatment systems needed to meet
the MY 2027 standards. In the 2023 Final Rule, the EPA received
comments from manufacturers and vehicle builders who indicated that,
for these applications, the timing and complexity of changes,
especially where aftertreatment may need to be mounted off the frame
rails or where space constraints are severe, can be more challenging
than for mainstream linehaul tractor configurations.
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\32\ See Chapter 1 of the DRIA for this proposed rule.
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In the past year, the EPA has heard from a number of engine
manufacturers and low-volume vehicle manufacturers that the challenges
discussed in the 2023 Final Rule continue to exist, and additional time
is needed for some specialized vocational vehicles. However, not all
engine manufacturers have NOX credits available to make use
of the flexibility. Removing the requirement to use NOX
credits, within the other existing requirements including the five
percent cap and limitation to Heavy HDE, would offer a practical, near-
term flexibility to bridge these constraints without expanding the
duration or volume of the allowance. In addition, due to the nature of
the heavy-duty industry that has a limited number of engine
manufacturers, the industry has made little use of the trading
provisions in the ABT program. As described in Chapter 1 of the DRIA
for this proposed rule, since MY 2012, only four NOX
emissions credit trades have occurred. The absence of trading and the
limited banks of NOX credits necessary for utilizing
production volume allowance reduces its effectiveness as a flexibility
and threatens the continued availability of the low volume HD vehicles
for which the provision was intended to address. This situation further
supports the proposed change to eliminate the requirement of using
NOX credits to access the interim production volume
allowance.
The proposed change affects only up to five percent of U.S.-
directed Heavy HDE production in MYs 2027 to 2029 and would have a
small impact on the emissions inventory. All other engines would remain
subject to the MY 2027 standards, and engines certified under the
allowance would still meet the MY 2026 requirements. This approach
preserves the core emissions benefits of the 2023 Final Rule while
addressing discrete implementation needs. See section VII of this
preamble and Chapter 2 of the DRIA for this proposed rule for more
details on the estimated emissions impacts of the proposed change to 40
CFR 1036.150(k).
[[Page 43166]]
The EPA requests comment on the proposed change to the MYs 2027-
2029 allowance under 40 CFR 1036.150(k), including whether it
appropriately balances the implementation needs and protection of
emissions benefits. (C-7). The EPA also requests comment on whether
this flexibility should apply to fewer MYs (e.g., only MY 2027, or MYs
2027 and 2028), or more MYs (e.g., also MY 2030 or beyond). The EPA
also requests comment on whether the five percent cap should be lower
or higher, and if the cap should remain constant or phase down over
time. See section III.D for other credit flexibilities the EPA may
consider to lower compliance costs and make implementation of standards
smoother.
D. Credit Flexibilities
In the 2023 Final Rule, the EPA established NOX FEL caps
at 65 mg/hp[middot]hr for MYs 2027 through 2030 and 50 mg/hp[middot]hr
for MYs 2031 and later. This prevents a manufacturer from certifying an
engine with NOX emissions greater than the FEL cap, even if
a manufacturer has enough emission credits to continue producing a type
of engine that is greater than the FEL caps.
In addition to establishing FEL caps, the 2023 Final Rule also
restricts NOX credits that can be used in MYs 2027 and later
to those credits earned beginning in MY 2022. NOX credits
from MYs 2021 and earlier can be used through MY 2026, but not beyond.
The 2023 Final Rule also retained the EPA's historical approach of
separate averaging sets based on primary intended service class: heavy-
duty spark-ignition engines (Spark-Ignition HDE), light heavy-duty
engines (Light HDE), Medium HDE, and Heavy HDE. NOX
emissions ABT is only allowed within each of these averaging sets; that
is, no emissions can be averaged or traded between the categories.
Additional information on the 2023 Final Rule ABT program provisions,
as well as the industry NOX emissions credit banks through
MY 2024, can be found in Chapter 1 of the DRIA for this proposal.
In the past year, multiple regulated entities requested the EPA
modify the NOX ABT program for MYs 2027 and later. This
section III.D summarizes and solicits comment on whether to increase
the NOX FEL cap, allow the use of NOX credits
across engine service classes (i.e., Spark-Ignition HDE, Light HDE,
Medium HDE, and Heavy HDE), and allow the use of NOX
emission credits generated prior to MY 2022.
1. NOX FEL Cap
The EPA recognizes that increasing the FEL cap, even in the short-
term, could reduce the economic costs of the requirements, potentially
without significant foregone emissions reductions. However, the EPA
also recognizes that doing so would be a change in Agency position. In
the 2023 Final Rule, the NOX FEL cap was set below the
existing standard of 200 mg/hp[middot]hr to avoid competitive
disruptions and ensure that the majority of new engines introduced into
commerce would include updated emissions control technologies compared
to the emissions control technologies manufacturers were using to meet
the existing standards.\33\ The EPA also explained in the 2023 Final
Rule that this was consistent with the Agency's past practice when
issuing rules for heavy-duty onroad engines or nonroad engines in which
there was a substantial (i.e., greater than 50 percent) difference
between the numeric levels of the existing and new standards).\34\
Comments received on the 2023 Final Rule from manufacturers suggested
that the EPA should set an FEL cap at a level between 50 and 100 mg/
hp[middot]hr, stating that such a cap would help to prevent competitive
disruptions (i.e., require all manufactures to make improvements in
their emissions control technologies). In the 2023 Final Rule, the EPA
explained that the specific numeric levels of the final FEL caps were
selected to balance several factors. The EPA stated that these factors
include providing sufficient assurance that lower-emissions
technologies will be introduced in a timely manner, which was
consistent with the Agency's past practice,\35\ and providing
manufacturers with flexibility in their product planning or assurance
against unforeseen emissions-related problems that may arise. In the
2023 Final Rule, the EPA explained that the FEL cap of 65 mg/
hp[middot]hr selected for the early years of the program (i.e., MYs
2027 through 2030) placed more emphasis on providing manufacturers
flexibility and assurance against unforeseen emissions control issues
to ensure a smooth transition to the new standards and avoid market
disruptions, as a smooth transition in the early years of the program
helps ensure the public health benefits of the final program by
avoiding delayed emissions reductions due to slower fleet turnover than
may occur without the flexibility of the ABT program in the 2023 Final
Rule. In the 2023 Final Rule, the EPA stated that the FEL cap of 50 mg/
hp[middot]hr selected for the later years of the program (i.e., MYs
2031 and later), placed more emphasis on ensuring continued
improvements in the emissions control technologies installed on new
engines.
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\33\ 88 FR 4296 at 4393.
\34\ 69 FR 38997 (June 29, 2004); 66 FR 5111 (Jan. 18, 2001).
\35\ See 69 FR 38997 (June 29, 2004).
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At the time of this proposed rule, engine manufacturers are
generally making progress toward adopting new emissions control
technologies to meet the standards; however, one engine manufacturer
has indicated that an increased FEL cap of 200 mg/hp[middot]hr for up
to two MYs could help them in the transition to meeting the MYs 2027
and later standards. With respect to potential emissions impact, the
EPA notes that a company would only be able to make use of a higher FEL
cap if the company had NOX credits available. See Chapter 1
of the DRIA for this proposal for a discussion of emissions ABT and
data regarding engine manufacturers' NOX credit balances.
The EPA notes that if a higher NOX FEL cap were
established in the final rule of this proposal, this would be optional
and would not require any company to make use of the higher FEL cap.
The EPA notes that some engine manufacturers may have concerns with the
change in the competitive landscape from an increase in the FEL cap, as
a higher FEL cap may allow a firm to sell an engine with a less-
effective emissions control technology at a lower cost.
The EPA requests comment on increasing the NOX FEL cap
to a level greater than 65 mg/hp[middot]hr, but less than or equal to
the MY 2026 standard of 200 mg/hp[middot]hr. (C-8) The EPA also
requests comment on the number of MYs over which a higher FEL cap
should apply, including whether it is appropriate to not include an end
date for a higher FEL cap. For example, the EPA may consider a higher
FEL cap for a few MYs during the transition to the lower NOX
standard followed by a return to 65 mg/hp[middot]hr, followed by the 50
mg/hp[middot]hr cap for MYs 2031 and later, or an alternative level, or
an increase in the FEL cap without a specified MY end date. The EPA
requests comment on the possible economic and emissions impacts of
allowing older credits to be used in the MYs 2027 and later program.
The EPA also requests comment on any reliance interest engine
manufacturers or others may have, including the specific reliance
concerns and available data supporting a reliance argument.\36\
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\36\ See section II.E of this preamble.
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[[Page 43167]]
2. Use of Pre-MY 2022 Emission Credits
The EPA recognizes that allowing the use of pre-MY 2022 emission
credits would be a change in Agency position. The 2023 Final Rule
restricted credit use to those generated in MYs 2022 and later, noting
that a majority of the existing credit balances were accumulated before
MY 2009 to create flexibility in transitioning to the MYs 2007-2010
standards and those credits were generated from engines without modern
emissions control technologies.\37\ Additionally, to account for the
addition of a new low-load test cycle (LLC), standard and moving
average window in-use test procedures and emission standards for MYs
2027 and later, and the resulting difference in emission controls, the
2023 Final Rule applies up to a 40 percent discount on NOX
credits earned between MYs 2022 and 2026 when those credits are used in
the MYs 2027 and later program. By applying these restrictions, the
2023 Final Rule expected to incentivize manufacturers to maximize their
development and introduction of the best available emissions control
technologies ahead of when they are required to do so in MY 2027,
instead of relying on older credits.
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\37\ 88 FR 4296 at 4395.
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As noted previously, at the time of this proposed rule, engine
manufacturers are generally making progress toward adopting new
emissions control technologies to meet the standards. The EPA's
proposals to expand access to the existing transitional production
volume allowance for Heavy HDE and establish NCPs for Medium HDE and
Heavy HDE are also expected to help manufacturers needing additional
time to transition to the MYs 2027 and later standards for those engine
categories. However, some manufacturers have expressed an interest in
using the pre-MY 2022 credits. Manufacturers have indicated the pre-MY
2022 credits could be used as an alternative to the use of NCPs, or
could be used for other product planning purposes, such as to increase
the FEL of a MY 2027 or later engine family, and/or to increase the
number of engines produced in the future at a given FEL above the
standard.
The EPA notes that if the use of pre-MY 2022 credits were allowed
in the final rule of this proposal, this would be optional. The EPA
notes that some engine manufacturers may have concerns with changing
this credit use provision due to potential changes in the competitive
landscape from the use of older credits, as a firm may now be able to
sell an engine with a less-effective emissions control technology at a
lower cost.
The EPA requests comment on whether, and how, banked NOX
emission credits earned prior to MY 2022 should be allowed for use in
MYs 2027 and later. (C-9). As shown in Chapter 1 of the DRIA for this
proposed rule, no NOX emission credits were generated in MYs
2010-2021, so allowing pre-MY 2022 credits would in practice be credits
generated in MYs 2004-2009. The EPA notes that some of the MY 2004 to
MY 2009 engines may be nearing the end of their practical use (or have
been retired or scrapped) and on average are accumulating fewer annual
vehicle miles relative to MYs 2027 and later engines.\38\ Furthermore,
as noted previously, credits generated from MYs 2004 to 2009 engines
were generated by engines without modern emission controls and relative
to different test procedures and standards. A discount of up to 40
percent is applied when using credits earned during MYs 2022-2026 for
MYs 2027 and later, and the EPA requests comment on an appropriate
discount that could be applied to credits earned from the MYs 2004 to
2009 engines for use in MYs 2027 and later. Finally, the EPA requests
comment on the possible economic and emissions impacts of allowing
these older NOX credits to be used in the MYs 2027 and later
program. The EPA also requests comment on any reliance interest engine
manufacturers or others may have, including the specific reliance
concerns and available data supporting a reliance argument.\39\
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\38\ As shown in the relative mileage accumulation rates of
Figure 6-4 in the MOVES Technical Report ``Population and Activity
of Onroad Vehicles in MOVES5'' (EPA-420-R-24-019, November 2024),
Single Unit Trucks and Combination Trucks that are 20 years or older
are predicted to travel 75 percent fewer miles than their new
counterparts. https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P101CUN7.pdf.
\39\ See section II.E of this preamble.
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3. Credit Use Across Averaging Sets
The EPA recognizes that allowing the use of emission credits across
averaging sets would be a change in Agency position. The EPA first
established the NOX emission credit banking and trading
flexibilities for heavy-duty engines in 1990, which expanded the
averaging program already in place for those engines.\40\ That 1990
rule continued the use of averaging sets to denote the heavy-duty
engine subcategory within which credits could be averaged, banked, or
traded. The EPA established a single averaging set for all Spark-
Ignition HDE, referred to as ``Otto-cycle engines'' at the time, and
light, medium, and heavy averaging sets for compression-ignition HDE
(``diesel cycle engines''). That 1990 rule expanded the existing
averaging set restrictions to include trading and banking such that
emission credit averaging and trading are not permitted between
averaging sets and banked credits can only be used in the averaging set
in which they were generated.\41\ In the proposal to that 1990
rule,\42\ the EPA justified the averaging set restrictions by noting
concern that cross-subclass credit exchanges would affect the
environment and competition. In the 1990 final rule, the EPA noted that
commenters requesting the Agency permit such an approach did not offer
solutions that would adequately address the concerns discussed in the
proposed rule.
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\40\ 55 FR 30534 (July 26, 1990).
\41\ Id. at 30588.
\42\ 54 FR 22670 (May 25, 1989).
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The 2023 Final Rule retained the existing averaging sets (i.e.,
Spark-Ignition HDE, Light HDE, Medium HDE, Heavy HDE) and allowed ABT
only within those averaging sets. The 2023 Final Rule noted the
approach was consistent with the Agency's historical approach, which
avoids creating unfair competitive advantages or environmental risks
due to credit inconsistency.\43\ The 2023 Final Rule did include one
temporary exception allowing credits generated by MY 2026 Heavy HDE to
be used for certifying Medium HDE after applying a 10 percent
discount.\44\ This exception was intended as a transitional credit
pathway to encourage the early introduction of lower-emitting engines
as manufacturers prepared for the new MYs 2027 and later program.\45\
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\43\ See 55 FR 30585 (July 26, 1990); 66 FR 5002 (Jan. 18,
2001).
\44\ See the 2026 service class pull ahead transitional credit
pathway under 40 CFR 1036.150(a)(4).
\45\ See 88 FR 4296 at 4397 and Attachment 5 to the 2023 Final
Rule's Stakeholder Meeting Log in the docket for that rule: https://www.regulations.gov/document/EPA-HQ-OAR-2019-0055-2895 for a
discussion of the 10 percent cross-service class credit discount.
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The EPA requests comment on whether and how emission credits could
be utilized between engine service classes. (C-10). As included in the
2023 Final Rule, specific limited allowances for cross-averaging set
transfers have been allowed to encourage the early introduction of
lower-emitting engines during the transition to new emission standards.
These flexibilities allow manufacturers, for a limited period, to focus
their investments on a specific service class
[[Page 43168]]
and then use those emission credits in other services classes. If the
EPA were to finalize an allowance for cross-averaging set trading, it
could similarly allow manufacturers to prioritize their resources.
If the EPA were to allow cross-averaging set NOX credit
transfers, the Agency requests comment on whether a credit discount
should be applied, the value of such a discount, and if that discount
should differ depending on from which averaging set the credits come.
For example, in the ``2026 service class pull-ahead credits'' provision
in 40 CFR 1036.150(a)(4), credits generated from the certification of
Heavy HDE can be used to certify Medium HDE after a 10 percent discount
is applied. A credit discount can help address the concern of credit
emissions value inconsistency between averaging sets. Emission credits
are determined from the difference in the FEL of the engine family and
the standard (in mg/hp[middot]hr), the work over the duty cycle miles
(in hp[middot]hr/miles) for each engine family, the number of engines,
and the useful life (in miles) of engines in each averaging set. There
are uncertainties in real-world work and miles traveled for the range
of vehicles in an averaging set compared to the certification duty
cycles, and the useful life of each averaging set can have a different
relationship to the real-world operating life of the range of engines
in the averaging set. These uncertainties could result in an
underestimate or overestimate of the true value of the emissions
credit. However, since the existing averaging sets were established,
the EPA has accepted the uncertainties within averaging sets such that
the parameters used in the credit calculation generally represent the
engines within each averaging set and ensure that a calculated
emissions credit has a consistent relationship to an emissions change
in the environment within a given averaging set.\46\ However, the
uncertainties are compounded when considering the relationship between
calculated and real-world emissions across averaging sets, and the use
of a discount factor can help balance those uncertainties to ensure
that credit trading between service classes is environmentally
protective.
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\46\ 55 FR 30585 at 30588.
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The EPA notes that if credit use across averaging sets is allowed
in the final rule of this proposal, this would be optional and would
not require any company to make use of the flexibility. The EPA notes
engine manufacturers may have concerns with the change in the
competitive landscape, since finalizing such an allowance close to the
implementation date could result in only benefiting manufacturers that
sell engines in more than one engine service class.
Finally, the EPA requests comment on the possible economic and
emissions impacts of allowing credits to be used across averaging sets
in the MYs 2027 and later program. The EPA also requests comment on any
reliance interest engine manufacturers or others may have, including
the specific reliance concerns and available data supporting a reliance
argument.\47\
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\47\ See section II.E of this preamble.
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4. Combination of the Requests
The EPA recognizes that the three requests for comment in this
preamble section III.D. have potential interactions. For example, if
the EPA were to finalize all three elements (an increase in the
NOX FEL Cap, use of pre-MY 2022 NOX credits, and
use of NOX credits across engine service classes), this
could reduce the compliance costs for some companies, while potentially
negatively impacting other companies due to a change in the competitive
landscape. The same is true if two of the three credit flexibilities
were included in the final rule of this proposal, independent of the
combination, as not all companies have pre-MY2022 NOX
credits, and not all heavy-duty engine companies sell engines in
multiple service classes. The EPA requests comment on the potential
interactions of these three credit flexibilities, including the impacts
on the overall emissions reductions of the MYs 2027 and later program,
the costs of the program, and any potential impacts on the competitive
landscape for the regulated industry. (C-11).
E. Other Regulatory Amendments
To further aid in the implementation of the MYs 2027 and later
heavy-duty engine emissions program, the EPA is proposing discrete
revisions across a range of issues to correct or clarify regulatory
provisions. This section III.E describes the background and purpose of
many of those individual proposed amendments. In several cases, this
section III.E also describes the types of proposed amendments without
listing all the specific instances for which the EPA is proposing to
change the regulations in the same manner. For example, some proposed
amendments simply correct inaccurate cross-references, fix
typographical errors, reproduce figures, tables, or equations to
correct publishing errors, remove obsolete or redundant content, or
make modest changes to maintain consistent terminology or improve
clarity. The EPA is also proposing to update the regulations to reflect
office reorganization within the Agency, with new work unit titles
where staff contact information is provided.
It is important to note that while this proposed rule includes a
range of amendments to the regulations, the EPA is not reopening and is
neither proposing nor requesting comment on the changes to underlying
standards or program requirements.
1. Proposed Revisions for Heavy-Duty Engines (40 CFR part 1036)
a. 40 CFR Part 1036, Subpart B--Emission Standards and Related
Requirements
Heavy-duty engine manufacturers have the option to test hybrid
powertrains rather than testing an engine alone to demonstrate
compliance with the emission standards of 40 CFR part 1036. In 40 CFR
1036.101(b), the EPA proposes to further clarify the existing
requirement that manufacturers can only use the powertrain testing
option if they demonstrate compliance with all the requirements of 40
CFR part 1036. For example, if an engine manufacturer chooses
powertrain testing to demonstrate that their hybrid configuration meets
the engine criteria pollutant standards of 40 CFR 1036.104, they must
also use powertrain testing to demonstrate that it meets the OBD
requirements of 40 CFR 1036.110.
Under existing 40 CFR 1036.104(a)(3), compression-ignition engine
NOX standards for off-cycle testing are adjusted for ambient
temperature over a shift day. In Table 3 to 40 CFR 1036.104(a), the EPA
proposes to revise the table heading for the adjustment column from
``Temperature adjustment'' to a more accurate and clearer
``Temperature-based adjustment for NOX''. The EPA is also
proposing to revise the footnote in Table 3 to provide further clarity
on the units for temperature in the adjustment equation and note the
final units of g/hr for Bin 1 and mg/hp[middot]hr for Bin 2 for the
temperature-based adjustment to the specified NOX standard.
The EPA is proposing to reorganize the existing introductory text
of 40 CFR 1036.125 to begin with the instruction to manufacturers to
give the ultimate purchaser of each new engine written instructions for
maintaining and using the engine, consistent with other parts. The EPA
is also proposing corrections to Table 1 to paragraph (a)(2) of Sec.
1036.125 to add missing parentheses, and to correct the maintenance
interval for Medium HDE ``Catalyst system components, EGR system
components
[[Page 43169]]
(other than filters or coolers), particulate filtration system
components, and turbochargers'' in Table 2 to paragraph (a)(2) of Sec.
1036.125 by replacing the 50,000 miles interval with 150,000 miles as
intended, consistent with the interval for Heavy HDE. The EPA is
proposing to revise Table 1 to paragraph (a)(2) of Sec. 1036.125 to
allow shorter minimum maintenance intervals for catalyst substrates and
particular filter substrates before MY 2030, consistent with proposal
to delay the longer regulatory useful life periods for heavy-duty
engines. In Table 1, the EPA proposes that the minimum maintenance
interval mileages for catalyst substrates and particulate filter
substrates that would apply to MYs 2029 and earlier engines would match
the useful life mileages that apply for those MYs. The proposed hours-
based intervals are calculated using an average speed of 33 miles per
hour, consistent with the existing intervals.
Under the existing maintenance regulations of 40 CFR 1036.125,
owners are responsible for properly maintaining their engines, and the
regulation notes in paragraph (g) that this generally includes paying
for scheduled maintenance. The EPA is proposing to revise 40 CFR
1036.125(g) to further clarify that an owner's responsibility generally
includes paying for scheduled maintenance even if it is within the
warranty period. As part of their certification, a manufacturer must
demonstrate that any critical maintenance must occur at a given
interval, and the maintenance intervals for certain components (e.g.,
spark plugs, crankcase filters) may be more frequent than the warranty
period of an engine but that does not suggest a manufacturer must cover
those costs for scheduled maintenance.\48\ The EPA notes that there are
circumstances in which a manufacturer offers maintenance for a
component free of charge to their customers as part of the maintenance
demonstration under 40 CFR 1036.125(a)(1)(iv) or because it is required
under the conditions specified in 40 CFR 1036.125(g). In these cases,
the maintenance instructions within the owner's manual would include
this information and the owner would not be responsible for paying for
scheduled maintenance on that component.
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\48\ See the emission-related warranty periods specified in 40
CFR 1036.120(b) and the minimum maintenance intervals specified 40
CFR 1036.125(a).
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The EPA is proposing to revise the installation instruction
provisions under 40 CFR 1036.130. This proposed revision would add a
new paragraph (b)(10) providing the manufacturers certifying powertrain
families, under 40 CFR part 1036, would include a description of any
limitations on the type or configuration of vehicles in which the
powertrain could be installed in their installation instructions for
vehicle manufacturers.
The EPA is proposing to add a new interim provision 40 CFR
1036.150(aa) that would allow engine manufacturers to use deterioration
factors generated from durability data generated with service
accumulation hours determined with prescribed test sequence 1 and 2
speeds of 40.26 mi/hr and 44.48 mi/hr respectively in 40 CFR 1036.245,
for engine families that qualify for carryover certification as
described in 40 CFR 1036.235(d). The EPA is proposing to eliminate the
default average vehicle speeds of 40.26 mi/hr and 44.48 mi/hr for test
sequences 1 and 2, respectively, in 40 CFR 1036.245(c)(7) that are used
in the total service accumulation hours calculated using Equation
1036.245-1. The default values underestimate the aging hours for Light
and Medium HDE because the vehicles in which these engines are
installed are vehicles that operate at lower average speeds than those
of test sequences 1 and 2. This can result in total service
accumulation hours that are too low, which results in inadequate time
to adequately account for catalyst chemical exposure and thermal
exposure due to infrequent regeneration events. The current solution,
to address the underestimation of aging hours from the use of average
vehicle speeds of 40.26 mi/hr and 44.48 mi/hr, is for engine
manufacturers to extend the service accumulation hours beyond those
calculated using Equation 1036.245-1, which ensures that deterioration
factors determined using the current default test sequence average
vehicle speeds are not deficient. Given this current solution, the EPA
is proposing to allow their continued use for carryover engine
families. More details on this topic can be found in the discussion
surrounding the updates the EPA is proposing to 40 CFR 1036.245 in
section III.E.1.b of this preamble.
The EPA is also proposing revisions to the OBD provisions of 40 CFR
1036.110. The 2023 Final Rule included a requirement for manufacturers
to identify additional data stream signals as freeze-frame conditions.
The EPA is proposing to amend 40 CFR 1036.110(b)(8) to more clearly
describe how this requirement interfaces with the California Air
Resources Board (CARB) regulation at 13 California Code of Regulations
(CCR) 1971.1(h)(4.3).
The 2023 Final Rule included a requirement for manufacturers to
submit additional information as needed to demonstrate that they meet
the OBD requirements in 40 CFR 1036.110 that are not covered by CARB's
OBD program. The EPA is proposing to clarify in 40 CFR
1036.110(b)(11)(i) that for additional EPA OBD requirements, such as
in-cab display and data stream parameter requirements, this
demonstration can be achieved through attesting that these requirements
are met, in lieu of submitting additional test data.
The 2023 Final Rule included a requirement at 40 CFR 1036.110(c)(1)
for manufacturers to identify fault codes with an in-cab display for
any SCR- or diesel particulate filter (DPF)-related condition causing
the engine to initiate a speed reduction or torque derate. First, the
EPA is requesting comment on whether in-cab display information
requirements should remain part of the ``diagnostic system.'' (C-12).
The required in-cab display information is not always part of the OBD
system which may complicate the usual standardization efforts for
diagnostic system elements. Second, the EPA has learned that some
derate conditions may occur without the engine's diagnostic system
generating a fault code to display. The fault code might materialize
after some continued operation, or it may not come at all. To address
this concern, the EPA is proposing to amend the in-cab display
provision to require the displayed fault code ``as applicable''. The
engine's diagnostic system would need to display any code that is
available, as applicable. This proposed amendment is intended only to
allow manufacturers to design their in-cab display to omit a
requirement to display a code that has not yet been set.
The EPA is also proposing to revise the language in 40 CFR
1036.110(b) to clarify the intended incorporation by reference in 40
CFR 1036.810 of 13 CCR 1971.1 such that it matches the Agency's
position that diagnostics for hybrid components are only required if
hybrid components are optionally certified to criteria pollutant
standards with the engine through powertrain testing.
The EPA is proposing to remove the requirements for additional
data-stream parameters for spark ignition engines in 40 CFR
1036.110(b)(10). This requirement is not useful for some applications
such as natural-gas based spark ignition engines for which it would
generally report a value of zero, which would be confusing to
serviceability operations and not
[[Page 43170]]
aligned with the intent of adding data-stream parameters.
The EPA is proposing to incorporate certain changes CARB intended
to make to OBD through its 2022 OBD update and its 2025 Omnibus
Amendment rule.49 50 The EPA is proposing to align OBD test
procedures with EPA test procedures. Specifically, the EPA is proposing
that manufacturers can use the Federal Test Procedure cycle as defined
in 40 CFR 1036.512, and the Supplemental Emission Test as defined in 40
CFR 1036.510 in lieu of the procedures defined in 13 CCR 1971.1(c).
Similarly, the EPA is proposing that manufacturers can use the
accelerated aging test procedure and requirements in 40 CFR 1036.245
instead of the testing and data collection requirements in 13 CCR
1971.1(i)(2.3.4). This proposed change would help reduce testing burden
and harmonize test procedures for OBD and emission-related testing.
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\49\ California Air Resources Board. (2025) ``Appendix A-1:
Proposed Amendments to Omnibus Title 13 Regulation Order.'' https://ww2.arb.ca.gov/rulemaking/2025/orhdomnibus.
\50\ California Air Resources Board. (2022) ``Final Regulation
Order: Section 1971.1 of Title 13, CCR.'' https://ww2.arb.ca.gov/resources/documents/obd-ii-regulations-and-rulemaking.
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The EPA is proposing to allow manufacturers to use a test-out
threshold of 30 percent instead of the 15 percent referenced in 13 CCR
1971.1(e)(8.2.4)(A)(iii) for catalyzed PM filters to be exempt from
non-methane hydrocarbon (NMHC) conversion capability monitoring.\51\
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\51\ California Air Resources Board. (2025). See page 90 of
``Appendix A-1: Proposed Amendments to Omnibus Title 13 Regulation
Order.'' https://ww2.arb.ca.gov/rulemaking/2025/orhdomnibus.
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During the development of CARB's 2022 OBD update, CARB included
relaxation of requirements for feedgas generation performance
monitoring due to concerns regarding the lack of feasible monitoring
strategies.\52\ The EPA is proposing to harmonize the Agency's
regulations with changes to NMHC catalyst and DPF feedgas requirements
finalized in CARB's 2022 OBD update. Specifically, the EPA is proposing
that for OBD systems that have an NMHC catalyst conversion efficiency
monitor that fulfills the requirements of 13 CCR 1971.1(e)(5.2.2), the
manufacturer may use the NMHC catalyst conversion efficiency monitor to
fulfill the feedgas generation performance monitoring requirements of
13 CCR 1971.1(e)(5.2.3)(B).
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\52\ California Air Resources Board. (2022). See page 21 of the
``Final Regulation Order: Section 1971.1 of Title 13, CCR.'' https://ww2.arb.ca.gov/resources/documents/obd-ii-regulations-and-rulemaking.
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Further, for OBD systems that have a catalyzed PM filter NMHC
conversion monitor or are exempt from the catalyzed PM filter NMHC
conversion monitoring requirements in accordance with section 13 CCR
1971.1(e)(8.2.4)(A), the manufacturer is not required to meet the
feedgas generation performance monitoring requirements of 13 CCR
1971.1(e)(8.2.4)(B).\53\ The EPA is also proposing the alternative
approach of entirely waiving the requirements for catalyzed PM filters
in 13 CCR 1971.1(e)((8.2.4)(A) and (B) based on instead meeting the PM
filtering performance requirements in 13 CCR 1971.1(e)(8.2.1). These
flexibilities are important to avoid fault codes being set that may
improperly indicate a malfunctioned catalyst. The NMHC impacts can be
so low that they are not reliably measurable and test results can
instead be strongly influenced by test-to-test variation. The use of
the DPF Efficiency monitor is appropriate because DPF's generally
experience mechanical failure prior to catalyst failure due to their
operating conditions.
---------------------------------------------------------------------------
\53\ California Air Resources Board. (2022). See page 35 of the
``Final Regulation Order: Section 1971.1 of Title 13, CCR.'' https://ww2.arb.ca.gov/resources/documents/obd-ii-regulations-and-rulemaking.
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The EPA is also proposing to clarify that the regeneration events
counter associated with the in-cab display requirements in 40 CFR
1036.110(c)(2) is specific only to active and completed regeneration
events. Similarly, the EPA is proposing to clarify that the
requirements in 40 CFR 1036.110(c) are to display on-demand the
``lifetime'' rate of DEF consumption, not ``historical.''
The EPA is proposing to revise the in-cab display requirements in
40 CFR 1036.110(c)(1). These existing requirements state that when SCR-
or DPF-related problems occur that result in engine derates (including
inducements), that manufacturers must make the fault code responsible
for the derate available on-demand in the cab. With the proposal to
replace SCR-related derates with visible and/or audible notifications,
as described in section V of this preamble, the EPA is proposing to
update the text to clarify that this requirement pertains to fault
codes that change the status of an aftertreatment system and isolate
the display requirements that apply broadly from those that apply to
AECDs that result in an engine derate (i.e., for any DPF-related or
SCR-related derates that may remain). The EPA notes that some AECDs may
continue to result in engine performance derates for engine protection
events such as low coolant to avoid overheating and damaging the engine
or catastrophic damage to the aftertreatment system. The intent of the
original requirement in 40 CFR 1036.110(c)(1) was to properly
communicate what problem caused an engine derate to facilitate quick
repair. The proposed amendment is relevant even if the EPA finalizes
the proposal in section V.C.2 to replace SCR-related derates with
visible and/or audible notifications because the display requirements
also apply and would continue to apply to derates caused by the SCR or
DPF system.
Finally, the EPA is proposing to clarify in 40 CFR 1036.110(c)(4)
that manufacturers can use discretion to decide what to safely display
while the vehicle is in-motion, which may be a more limited set of the
required information than is displayed when the vehicle is stationary.
b. 40 CFR Part 1036, Subpart C--Certifying Engine Families
The EPA is proposing to amend 40 CFR 1036.205(r)(1) by referring to
``physically adjustable parameters'' instead of ``practically
adjustable parameters'' to conform to the terminology established in
the existing, more detailed provisions for adjustable parameters in 40
CFR 1068.50. Under those existing provisions, the regulations describe
how to determine the practically adjustable range for both physically
adjustable operating parameters and programmable operating parameters.
The EPA is proposing to clarify in 40 CFR 1036.235(b) how
manufacturers test their flexible-fuel emission-data engines.
Specifically, manufacturers may operate with the fuel mixture that best
represents in-use operation or is most likely to have the highest
NOX emissions, or they may test with both fuels separately
if they demonstrate to the EPA that intermediate mixtures are not
likely to occur. The EPA is also proposing to replace the incorrect
paragraph (a) reference in 40 CFR 1036.235(e) with a reference to
paragraph (b) that describes testing.
The EPA is proposing a revision in 40 CFR 1036.240(b) that adds
``duty-cycle'' to clarify the applicable emission standard. The EPA
also proposes to add a provision to 40 CFR 1036.240(c) allowing for
assigned deterioration factors for small-volume engine families. Each
manufacturer would be able to use assigned deterioration factors for
any number of engine families, up to a combined annual production
volume of 10,000 engines. This would restore certification provisions
that apply through MY 2026 under 86.094-14. As
[[Page 43171]]
part of the migration to 40 CFR part 1036, the EPA set up deterioration
factor requirements in 40 CFR 1036.240 and 1036.245 to broadly allow
companies to share deterioration factors across families using similar
technologies. Manufacturers have raised concerns that this approach
does not work for engines using alternative fuels or other technologies
that are not uniformly deployed across their product line. Allowing
assigned deterioration factors for small-volume engine families would
remove the significant test burden associated with durability testing
for those niche products. Such engines remain subject to the emission
standards throughout the useful life.
The EPA is proposing changes throughout 40 CFR 1036.245 to
accommodate the proposed addition of an accelerated aging procedure for
heavy-duty spark-ignition engines in 40 CFR part 1065, subpart L. See
the discussion of these changes in section III.E.3.j of this preamble.
The EPA is proposing to revise 40 CFR 1036.245(c) to clarify that
the deterioration factors must be based on representative deterioration
due to infrequent regeneration and that engine dynamometer hours
accumulated during emission testing do not count toward total service
accumulation hours. The EPA is proposing to revise 40 CFR
1036.245(c)(1) to clarify that the minimum engine dynamometer service
accumulation hours include the dynamometer engine stabilization time
accumulated prior to performing the low-hour emission measurement. The
EPA is proposing to revise 40 CFR 1036.245(c)(2) to allow manufacturers
to use the average of multiple emission tests to determine emission
values used to calculate the deterioration factor. The EPA is proposing
to allow this to minimize the influence of any variability associated
with the emission measurement.
In 40 CFR 1036.245(c)(4), (c)(4)(i), and (c)(4)(ii) the EPA is
proposing to clarify that, for hybrid powertrains, manufacturers may
conduct service accumulation under paragraphs (c)(4)(i) or (ii) without
the hybrid components by following 40 CFR 1037.551. The EPA is also
proposing to add new paragraphs (c)(4)(i)(F) and (ii)(F) to clarify how
to perform cycle validation during service accumulation, and state that
cycle validation needs to be performed on at least one of each duty
cycle type each time the engine is operated over the duty cycle
sequence. These proposed clarifications are appropriate for the same
reason described in the discussion of the proposed addition of the new
40 CFR 1036.245(c)(5) and (6).
The EPA is also proposing to clarify that spark-ignition engines
may exclude the LLC from the service accumulation test sequences in 40
CFR 1036.245(c)(4)(i) and (ii) as these engines are not subject to
certification over the LLC. The LLC has normalized speeds up to 106.4
percent. For spark-ignition engines with high-speed governors that are
just above the maximum power of the engine, a normalized speed of 106.4
percent puts the test speed above the governed speed when using typical
denormalization procedures. Thus, requiring service accumulation over
the LLC for spark-ignition engines would require the manufacturer to
apply the alternate maximum test speed provision in 40 CFR
1065.610(a)(2) not only for the LLC, but also the Federal test
procedure (FTP) and supplemental emissions test (SET) duty cycles.
Rather than force the engine manufacturers to test the engine over the
FTP and SET duty cycles at an alternate maximum test speed just to
accommodate the LLC, a duty cycle to which they are not required to
certify, the EPA is proposing to update 40 CFR 1036.245(a)(3) to allow
exclusion of the LLC for spark-ignition engines for the two-engine
service accumulation test sequences.
The EPA is proposing to add a new 40 CFR 1036.245(c)(5) and (6)
that includes alternative duty cycle validation criteria for service
accumulation for engine dynamometer testing. Meeting the existing cycle
validation criteria that are required for engine certification testing
is not as important for service accumulation when using an engine
dynamometer, especially when most of the service accumulation on the
aftertreatment system is being done via the accelerated aging procedure
in 40 CFR part 1065, subpart L. Furthermore, if one of the many duty
cycles run during service accumulation failed the existing cycle
validation criteria, the EPA recognizes that it would be impractical to
void all of the service accumulation testing to date because one duty
cycle did not pass the cycle validation criteria. The proposed revised
cycle validation criteria would help ensure that the duty cycles are
followed appropriately for service accumulation when using an engine
dynamometer, while also avoiding situations in which a duty cycle is
deemed invalid. Under the proposed provisions, setting the dynamometer
command to minimum and using the operator demand to control speed for
nonmotoring dynamometers would not adversely affect the aging of the
aftertreatment during service accumulation and would allow service
accumulation to be carried out on an eddy current dynamometer (which
cannot motor due to load imparted on the engine from cooling water and
bearing drag). Allowing the use of eddy current dynamometers under the
proposed provisions would also open up additional test cells for use in
service accumulation testing and increase test facility throughput.
In 40 CFR 1036.245(c)(7), the EPA is proposing to clarify that
emission measurements for all regulated pollutants must be taken after
the manufacturer finishes the required service accumulation that is
conducted on an engine dynamometer.
The EPA is proposing to add clarification to 40 CFR
1036.245(c)(8)(i) that the useful life milage used in the calculation
of the total service accumulation, representing hours of engine
operation over the useful life, is based on the longest useful life for
which the deterioration factors will be used. The EPA is proposing to
eliminate the default average vehicle speeds of 40.26 mi/hr and 44.48
mi/hr for test sequences 1 and 2 in 40 CFR 1036.245(c)(7) that are used
in the total service accumulation hours calculated using Equation
1036.245-1. The default values underestimate the aging hours for Light
and Medium HDE because the vehicles in which these engines are
installed are vehicles that operate at lower average speeds than those
of test sequences 1 and 2. This can result in total service
accumulation hours that are too low, which results in inadequate time
to accurately account for catalyst chemical exposure and thermal
exposure due to infrequent regeneration events. The current solution,
to address the underestimation of aging hours from the use of average
vehicle speeds of 40.26 mi/hr and 44.48 mi/hr, is for engine
manufacturers to extend the service accumulation hours beyond those
calculated using Equation 1036.245-1, which ensures that deterioration
factors determined using the current default test sequence average
vehicle speeds are not deficient. Under the proposed changes,
manufacturers are now directed to develop their own average vehicle
speed based on the applications used for determining the thermal
exposure for the engine family as described in the field data
discussion in 40 CFR 1065.1131 or 40 CFR 1065.1147. The EPA is also
proposing to require the use of an average vehicle speed of 20 mi/hr if
the average speed from the field data is less than 20 mi/hr. This is
because a speed of lower than 20 mi/hr will result in the service
accumulation hours exceeding the
[[Page 43172]]
useful life hours in Table 4 to paragraph (e) of 40 CFR 1036.104. The
EPA proposes to allow the use of previously developed deterioration
factors that used the test sequence default average vehicle speeds for
carryover engine families in 40 CFR 1036.150(aa) for engine families
that qualify for carryover certification as described in 40 CFR
1036.235(d). The EPA is also proposing in 40 CFR 1036.245(c)(8)(ii) to
clarify that the service accumulation duration could be different if
the testing is used for multiple primary intended service classes.
The EPA is proposing to clarify in 40 CFR 1036.245(c)(9) how to
calculate the number of hours of testing remaining to finish service
accumulation over the useful life for the accelerated bench aging of
aftertreatment devices portion of the testing.
The EPA is proposing to clarify in 40 CFR 1036.245(c)(10) on what
emission data engine the aftertreatment devices can be reinstalled once
the accelerated aging portion of the testing has been completed.
The EPA is proposing to clarify in 40 CFR 1036.245(c)(11) and (12)
references to applicable sections in the procedure in this section to
enhance the ability to follow what is being required.
The EPA is proposing to revise 40 CFR 1036.245(c)(13) to remove the
sentence instructing the manufacturer to create a linear curve fit of
the emission measurements if the deterioration factor testing included
multiple test points and proposing that the deterioration factor is
determined using the emission data from the low-hour and useful life
test points. Since the emissions measurements are made at the low-hour
and useful life for each standard, a linear curve fit of the emission
data is not needed and could result in unrepresentative results.
The EPA is proposing to add a new 40 CFR 1036.245(c)(14) to clarify
how to determine separate deterioration factors for engines
corresponding to a shorter useful life.
The EPA is proposing to correct a typographical error regarding the
spelling of ``stabilized'' in 40 CFR 1036.246(b)(1)(i)(C).
c. 40 CFR Part 1036, Subpart E--In-Use Testing
The EPA is proposing to revise 40 CFR 1036.410(c) to correct a
paragraph reference error. The section currently requires the
manufacturer to notify the EPA before disqualifying any vehicle based
on an illuminated malfunction indicator light (MIL) or stored OBD
trouble codes as described in 40 CFR 1036.415(b)(2). However, 40 CFR
1036.415(b)(2) concerns the appearance of a MIL during in-use testing
and how to address the MIL. The correct paragraph reference should be
40 CFR 1036.415(b)(3), which addresses vehicle disqualification due to
the presence of an MIL if the vehicle cannot be repaired in a timely
manner, which is the only provision that allows disqualification of a
vehicle due to an illuminated MIL.
The EPA is proposing to revise 40 CFR 1036.415(d), 1036.420(c) and
(d), and 1036.430(a)(3)(vii) to replace the term ``windows'' with
``test intervals'' as the Agency believes this term is clearer given
that the 300 seconds of data that are averaged for binning purposes
constitute a test interval. The EPA is also proposing to clarify that
if a manufacturer does not measure total hydrocarbon emissions (THC)
during the off-cycle emission test, they would set xTHCmeas
to zero in the chemical balance calculations required under 40 CFR
1065.655.
The EPA is proposing to add a new 40 CFR 1036.415(h) to clarify
that, for hybrid powertrains that do not operate the engine at zero
vehicle speed, the 1-Hertz (Hz) emission rate for all pollutants after
the engine has started must be set to zero when the engine is off, the
vehicle speed is zero, and the powertrain is keyed on and that the data
points should not be excluded under 40 CFR 1036.530(c)(3)(ii). This
proposed provision is similar to what currently exists in 40 CFR
1036.415(g) for stop-start and automatic engine shutdown systems and
allows test intervals to be accrued and counted toward the idle bin
minimum test interval limits when the engine is off.
The EPA is proposing to provide clarifications in 40 CFR
1036.420(d) on extending testing over multiple shift days to combine
test intervals to achieve the minimum test interval requirement for
each bin. The EPA proposes to include four examples of what
circumstances might lead to the extension of testing to an additional
shift day: data lost from gas analyzer range validation failure (40 CFR
1065.935(g)(5)(i)), drift validation failure (40 CFR
1065.935(g)(5)(ii)), excluded data (40 CFR 1036.530(c)(3)), and
insufficient operation during the shift day (40 CFR 1036.415(f)).
The EPA is proposing changes to 40 CFR 1036.420(d) and 40 CFR
1036.425(c) to clarify how to determine the average ambient temperature
used to calculate the off-cycle NOX emission standard in 40
CFR 1036.104(a)(3). The EPA is proposing in 40 CFR 1036.420(d) to
determine the mean ambient temperature, Tamb, by averaging
the continuous ambient temperature, Tamb, over all shift
days needed to reach the minimum test interval requirements for each
bin. The EPA is proposing changes to 40 CFR 1036.425(c) to clarify that
the mean ambient temperature is determined by taking the mean of
Tamb from each of the engine tests.
The EPA is proposing in 40 CFR 1036.420(d)(2) to clarify that, for
hybrid powertrains that do not operate the engine at zero vehicle
speed, the manufacturer may populate Bin 1 with additional test
intervals by setting the 1-Hz emission rate for all regulated
pollutants to zero as described in 40 CFR 1036.415(h). This proposed
provision is similar to what currently exists in 40 CFR 1036.420(d)(2)
for stop-start and automatic engine shutdown systems and allows Bin 1
to accumulate exactly 2,400 Bin 1 test intervals in instances in which
the number of test intervals falls short.
The regulation at 40 CFR 1036.430(a)(1)(ii) instructs manufacturers
to include a summary of the vehicles they have disqualified from in-use
testing and the reasons they disqualified them. The EPA is proposing to
revise 40 CFR 1036.430(a)(1)(ii) to clarify that for vehicles
disqualified from in-use testing for a MIL, the test report should
include a description of the illuminated MIL or stored OBD trouble
codes. The intent in 40 CFR 1036, subpart E, was for manufacturers to
notify the EPA of any vehicles disqualified from in-use testing due to
MIL illumination or OBD fault codes, and this proposed addition to 40
CFR 1036.430(a)(1)(ii) clarifies what information is expected to
support vehicle disqualification actions.
d. 40 CFR Part 1036, Subpart F--Test Procedures
The EPA is proposing to revise 40 CFR 1036.501(h) to clarify that,
for nonhybrid engines that qualify and use the powertrain test
procedures, the provisions specified for nonhybrid powertrain testing
should be used. For example, in 40 CFR 1036.520, for nonhybrid
powertrains, continuous rated power (Pcontrated) equals
rated power (Prated).
The EPA is proposing to add a new Figure 1 to 40 CFR 1036.501 to
provide an example of a test sequence for determining criteria
pollutant emissions for plug-in hybrid powertrains.
The EPA is proposing to revise 40 CFR 1036.510(c) to clarify that
testing over the SET duty cycle is required for both compression-
ignition and spark-ignition engines as SET standards exist for both
combustion types in 40 CFR 1036.104.
[[Page 43173]]
The EPA is proposing to revise Figure 1 of 40 CFR 1036.510, Figure
1 of 40 CFR 1036.512, and Figure 2 of 40 CFR 1036.545 by removing
``Engine Start'' to eliminate confusion for plug-in hybrid powertrains
in which the engine starts multiple times during charge-depleting
operation to blend engine and electric power.
The EPA is proposing to revise 40 CFR 1036.510(g), 1036.512(c),
1036.514(d), 1036.530(j)(1), and 1036.545(o)(7) to clarify that, for
hybrid powertrains, when determining total work over a test interval in
40 CFR 1065.650(d), system power (Psys) from 40 CFR
1036.520(f) is used in place of the shaft power determination in 40 CFR
1065.650(d)(2) and paragraph 40 CFR 1065.650(d)(6) does not apply. In
40 CFR 1036.514(d), the EPA is also proposing to clarify that
manufacturers would not exclude accessory loads when calculating total
work over the LLC. The proposed clarification would be helpful because
the direction in 40 CFR 1065.650(d)(6) to ``set all power values to
zero during idle periods with a corresponding reference torque of 0
N[middot]m'' could potentially lead someone to incorrectly believe that
the accessory loads in 40 CFR 1036.514(c) should be excluded from the
calculation of total work.
The EPA is proposing to revise 40 CFR 1036.510(b)(2) to clarify
that, for hybrid powertrain testing, the manufacturer may set the
battery to the lowest state-of-charge level that results in charge
sustaining operation after preconditioning to help meet the net-energy-
change requirement in 40 CFR 1036.545(a)(6). The EPA is also proposing
to add a reminder to follow 40 CFR 1065.610(d)(3)(ii) to apply optional
declared accessory loads. The EPA is proposing to revise 40 CFR
1036.510(b)(2)(iii) to correct the solution to the example problem for
the calculation of CdA.
The EPA is proposing to republish the SET duty cycle in 40 CFR
1036.510, Table 1, as the current version has only three significant
figures for the road-grade coefficients. This table was intended to
originally be published with four significant figures for these
coefficients to be consistent with the road grade coefficients in the
transient test interval for spark-ignition engines and powertrains
under 40 CFR 1036.512 in paragraph (b) of Appendix B to 40 CFR part
1036, the transient test interval for compression-ignition engines and
powertrains under 40 CFR 1036.512 in paragraph (c) of Appendix B to 40
CFR part 1036, and the transient duty cycle for compression-ignition
engines and powertrains under 40 CFR 1036.514 in paragraph (d) of
Appendix B to 40 CFR part 1036. The number of significant figures
influences the amount of work the engine does over the duty cycle.
Updating the SET road-grade coefficients from three to four significant
figures would result in a relatively large difference in work (up to 90
percent) for a few of the low power mode points, but would only result
in a total cycle work difference of less than 0.2 percent.
The EPA is proposing to remove the charge-depleting (CD) test
requirement for criterial pollutant testing for SET in 40 CFR
1036.510(d). The criteria pollutant testing requirements for CD testing
are currently not consistent with how CD testing has been historically
carried out on light-duty vehicles, for which CD testing is only
required on the FTP for criteria pollutant testing. When the EPA
originally drafted and finalized the CD criteria pollutant testing
requirements in the 2023 Final Rule, the Agency intended to put heavy
duty testing on par with light duty testing for plug-in hybrids. For
that to occur, CD testing for heavy-duty engines should only apply to
the FTP. Note that this proposed change requires moving the CD test
procedure from 40 CFR 1036.510(d)(2) through (4) to 40 CFR
1036.510(e)(1) through (3) as both charge-sustaining (CS) and CD
testing are still required over the SET for the National Highway
Transportation Safety Administration's (NHTSA) fuel economy program.
The EPA is proposing to update 40 CFR 1036.510(g) by adding new
subparagraphs (1), (2), and (3) to provide three exceptions when
calculating work over the test interval from hybrid powertrains as
described in 40 CFR 1065.650(d). These exceptions require determining
shaft power at each point in the test interval using the system power
from 40 CFR 1036.520(f) instead of calculating it according to 40 CFR
1065.650(d)(2) and not setting power values to zero as described in 40
CFR 1065.650(d)(6). Under this proposal, the first exemption is to keep
powertrain testing consistent with engine testing by requiring the
shaft power to be determined at the engine shaft regardless of where
power is measured. Under this proposal, the second exemption is needed
because the engine in a hybrid powertrain may start multiple times
during the test and it would be unrepresentative to zero out this
power, since the energy to start the engine is coming from the
powertrain. Under this proposal, the third exemption is needed to
correct the total work for criteria pollutant testing by the additional
energy from the battery if the net energy change (NEC) over the duty
cycle is greater than 1 percent and less than or equal to 5 percent.
The correction is needed because the total work of the powertrain
includes both the energy produced by the engine and the energy that
comes from the battery. The EPA is not proposing to allow correction to
total work if the NEC is less than -1 percent since the additional
energy in the battery may have come from regenerative braking near the
end of the duty cycle. In addition, the EPA is proposing in 40 CFR
1036.545(a)(6) to increase the tolerance of NEC from 1
percent to 5 percent.
The EPA is proposing to update 40 CFR 1036.512(c) to clarify the
total mass of each constituent and the total work over the test
interval is determined as described in 40 CFR 1036.510(g). This would
make this process consistent across duty cycles and test intervals.
The EPA is proposing to update 40 CFR 1036.512(d) to clarify the
determination of criteria pollutant emissions over the FTP for plug-in
hybrid powertrains, including adding a new 40 CFR 1036.512(d)(1)(i) to
carry out preconditioning of the engine or powertrain as described in
40 CFR 1065.518(c)(1).
The EPA is proposing to update the composite emission calculation
for criteria pollutant determinations for CD testing of plug-in hybrid
powertrains in 40 CFR 1036.512(d)(1)(iv). The FTP duty cycle was
designed such that the engine would have 20 minutes of operation,
starting from a cold soak, resulting in fully warmed-up operation prior
to the soak period that precedes the start of the hot-start test
interval. Testing of plug-in hybrid vehicles could result in a scenario
in which, during the CD testing, the engine starts near the end of the
test interval, resulting in the engine not being fully warmed up by the
end of the test interval. This would result in the inclusion of what
would be considered some cold-start operation in the hot-start test
interval, which could have the potential to bias the composite emission
value high, as the emissions from the hot-start test interval are 85.7
percent of the composite test cycle. To ensure that FTP emissions from
plug-in hybrid powertrains are treated in the same manner as regular or
hybrid powertrains, the EPA is proposing to calculate the composite
emission value as follows:
1. Determine the average of the sum of emissions over the first
test intervals in which engine operation occurs and the subsequent test
interval and add that to six times the emissions from the third
[[Page 43174]]
test interval, which is the true hot-start test interval.
2. Then divide that value by the average of the sum of the work
over the first test intervals in which engine operation occurs and the
subsequent test interval plus six times the work from the third test
interval, which is the true hot-start test interval.
The EPA is proposing to update Figure 1 to paragraph (d)(4) of 40
CFR 1036.512 to remove the arrow that denotes ``engine start'' as the
engine could start in other FTP test intervals without the engine
entering charge sustaining operation. The EPA is also proposing to
update the figure to support the proposed changes to 40 CFR
1036.512(d)(1)(iv).
The EPA is proposing to add a new Figure 1 to paragraph (d)(5) of
40 CFR 1036.512 to provide an example of the FTP CS criteria pollutant
test sequence to provide an illustration of how the test sequence is
carried out.
The EPA is proposing to revise 40 CFR 1036.514(a)(1)(i) to clarify
what is meant by the statement that ``Declared idle torque must be
zero.'' This proposed clarification is that the use of the optional
declared idle torque in 40 CFR 1065.510(f)(5)(iii) is not allowed and
must be zero. The EPA is proposing to revise 40 CFR 1036.514(b) to
delete the existing paragraph 40 CFR 1036.514(b)(4) because there are
no adjustments made to the procedures in the referenced 40 CFR
1036.510(d). The EPA is proposing to relocate the exception to replace
``SET'' with ``LLC'' to 40 CFR 1036.514(b)(1) and renumber subsequent
paragraphs as the replacement of SET with LLC should be first in the
order of exceptions.
The EPA is proposing to revise 40 CFR 1036.514(d) to reference 40
CFR 1036.510(g) to calculate the total mass of each constituent and the
total work over the test interval rather than describing such in this
paragraph. Doing this would provide one common location for total mass
and work determination, including exceptions for hybrid powertrain
testing. The EPA is also proposing to add a reminder that the work for
accessory loads is not excluded from the work calculation as the LLC
duty cycle has accessory load requirements that must be included.
The EPA is proposing to revise 40 CFR 1036.520(d) to clarify that
when the manufacturer carries out the powertrain power and vehicle
speed determination, the state-of-charge of the rechargeable energy
storage system (RESS) must be at a representative level to deliver
maximum power. The EPA is also proposing to change the warmup cycle to
the FTP, rather than a recommendation of any vehicle speed and road
grade that results in 75 percent of maximum power, to standardize the
warmup and provide a level playing field across engine manufacturers.
The EPA is also proposing to provide an initial ramp up of the vehicle
speed to five mi/hr with a five second hold at this speed as the
initial acceleration was not intended to be wide-open throttle from the
initial depression of the pedal, which could cause problems for some
powertrain architectures. The EPA is also proposing to alter the wide-
open throttle maneuver after the five second hold at five mi/hr to ramp
to the maximum driver demand for full load acceleration within three
seconds. The EPA anticipates that these adjustments would provide some
relief to the powertrain from the aggressive acceleration.
The EPA is proposing to revise 40 CFR 1036.520(e) and (f) to
replace occurrences of ``transmission input'' with ``engine's primary
output'' since the output shaft of the engine is the more commonly used
term to identify where system power is determined for a conventional
powertrain configuration.
The EPA is proposing to revise 40 CFR 1036.520(h) and (k)(2) to
change the maximum coefficient of variation (COV) of the vehicle system
power from two percent to one half of one percent. The COV is used to
select data that determine measured rated power, which is then used to
determine rated power and continuous rated power. The EPA is proposing
this change because recent data from engine hybrid testing in which the
transmission is simulated have shown that measured rated power is
elevated during transmission upshift events, which can result in
unrepresentatively high determinations of rated power and continuous
rated power. Reducing the maximum COV of measured rated power from two
percent to one half of one percent would lead to more representative
values of rated power and continuous rated power by reducing the
influence of shifting.
The EPA is proposing to limit the values of Pcontrated
and Prated, determined in 40 CFR 1036.520, for hybrids and
plug-in hybrid powertrains. These values are used for determining the
vehicle test mass and road grade in 40 CFR 1036.510, 1036.512, and
1036.514, using the equations in 40 CFR 1036.510. The equations were
developed based on the rated power of non-hybrid diesel engines and
with the assumption that hybrid powertrains would be designed to have
comparable rated power to their non-hybrid diesel engine
counterparts.\54\ However, if a hybrid powertrain is designed to have
higher rated power than its non-hybrid diesel engine counterparts,
calculated values for vehicle test mass and road grade can result in a
duty cycle that is not representative for the hybrid powertrain. To
illustrate this, for example, the EPA has estimated that the Tesla Semi
\55\ has a Pcontrated of 740 kilowatts (kW), which would
result in a vehicle test mass of 86,630 kg (190,987 pounds) using Eq.
1036.510-1.\56\ In this case, the vehicle test mass is not
representative since the vehicle has a gross combined vehicle weight
rating of 82,000 pounds. The EPA proposes to address this in 40 CFR
1036.520 by limiting the values of Pcontrated and
Prated to the maximum value of rated power of non-hybrid
diesel engines in that category. The EPA proposes to use the
certification data for MY 2021 to 2024 diesel engines, which would
result in the maximum rated power for Light HDE, Medium HDE, and Heavy
HDE of 260, 340, and 450 kW, respectively.\57\ For spark-ignition HDE,
the EPA proposes using the same 260 kW value used for Light HDE. These
rated power values would result in a maximum vehicle test mass of
22,009, 31,276, and 45,153 kg for Light HDE, Medium HDE, and Heavy HDE,
respectively, using Eq. 1036.510-1. These values for vehicle test mass
are comparatively high for vehicles with Light HDE, Medium HDE, and
Heavy HDE, but the EPA's analysis supports that the power demand from
the cycles would be representative when accounting for the
corresponding road grade in each of the FTP, SET, and LLC duty
cycles.\58\
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\54\ Memorandum to docket EPA-HQ-OAR-2026-0728. ``Summary of the
Development of the Powertrain FTP, SET, and LLC Duty Cycles.'' June
2026.
\55\ There are currently no publicly available data on the rated
power from heavy-duty plug-in hybrids. For this illustration, the
EPA instead used the rated power of heavy-duty battery electric
vehicles since the same e-motors can be used for plug-in hybrids and
battery electric vehicles.
\56\ The Pcontrated of the Tesla Semi was estimated
by using the performance specifications from Tesla's website (see
www.tesla.com/semi) of zero to 60 miles per hour (MPH) in 20
seconds, with a gross combined vehicle weight rating of 82,000 lbs
and physics-based calculations for heavy-duty vehicles.
\57\ The certification data for diesel engines were used since
data from diesel engines were used to develop the equations in 40
CFR 1036.510 for defining the vehicle model. Values were determined
using rated power expressed to the nearest 10 kW. See Heavy-Duty
Highway Gasoline and Diesel Certification Data (Model Years: 2015-
Present). www.epa.gov/compliance-and-fuel-economy-data/annual-certification-data-vehicles-engines-and-equipment.
\58\ Memorandum to docket EPA-HQ-OAR-2026-0728. ``Summary of the
Development of the Powertrain FTP, SET, and LLC Duty Cycles.'' June
2026.
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[[Page 43175]]
The EPA is proposing to update the emission sampling duration in
the clean idle test in 40 CFR 1036.525(b)(3) from 1,200 second to 1,800
seconds to align this test with the CARB test procedure in 13 CCR
1956.8.
The EPA is proposing to add a new paragraph (c) to 40 CFR 1036.530
to add the already-existing requirement to perform drift verification
as described in 40 CFR 1065.935(g)(5)(ii) and (iii). The EPA is also
proposing to clarify that, for drift verification of CO and HC under 40
CFR 1065.935(g)(5)(ii), the manufacturer must determine a corrected
value of the off-cycle emission values for Bin 2 in g/kW[middot]hr
using equation 1036.530-3 for each interval between analyzer
verifications. Under this proposal, the corrected value is then
compared to the uncorrected value or to the Bin 2 emission standard in
40 CFR 1036.104(a)(3), whichever is greater, to determine whether the
drift is within the specified percentage limit in 40 CFR
1065.935(g)(5)(ii). The EPA notes that carbon dioxide (CO2)
drift correction and verification is based on the mass of
CO2 as described in 1065.935(g)(5)(ii), which references 40
CFR 1065.550(b)(3)(ii)(A). Since there is no off-cycle standard for
CO2, 40 CFR 1065.550(b)(3)(ii)(A) indicates that the
verification is done on a mass basis. The EPA notes that the
NOX drift verification is based on an analyzer zero-
verification limit of 2.5 parts per million (ppm) for each
interval between analyzer verifications, a zero-drift limit over the
shift day of 10 ppm, and a span-drift limit for each
interval between analyzer span verifications of 4 percent
of the measured span gas value. The EPA is proposing to revise 40 CFR
1036.530(c)(2) to replace the term ``windows'' with ``test intervals''
as the Agency believes this term is clearer given that the 300 seconds
of data that are averaged for binning purposes constitute a test
interval. The EPA is proposing to revise 40 CFR 1036.530(c)(3)(ii) to
clarify that no data is valid when the operator has the engine off
beyond the existing exceptions for stop-start and automatic engine
shutdown systems and a proposed additional exception for certain hybrid
powertrains. Hybrid powertrains for which the engine does not operate
at zero vehicle speed when the powertrain is keyed on work in a similar
manner to stop-start and automatic engine shutdown technologies by
eliminating engine idle when the engine is off, the vehicle speed is
zero, and the powertrain is keyed on. The EPA is proposing to add a
cross-reference to the newly proposed 40 CFR 1036.415(h) to
consistently allow this hybrid powertrain type of idle reduction
technology to report an emission rate of zero during these scenarios.
The EPA is also proposing to add two test interval data condition
exclusions at 40 CFR 1036.530(c)(3)(viii) and (ix), gas analyzer range
validation failure according to 40 CFR 1065.935(g)(5)(i) and any data
that does not meet the drift criteria in 40 CFR 1065.935(g)(5)(ii).
This data is currently required to be excluded under existing 40 CFR
1065.935(g)(5); however, the EPA is proposing conforming additions
under this provision for completeness and clarity, to make it easier
for manufacturers to locate all the exclusion requirements in one
place. The EPA is additionally proposing to revise the variable
description for eCO2FTPFCL in 40 CFR 1036.530(e) to clarify
that it is also the CS CO2 emissions over the FTP duty cycle
for plug-in hybrid powertrains. The variable eCO2FTPFCL is
used as a surrogate for work and, if the CD CO2 under the
existing variable description was used, it would give a reduced work
value as the CO2 emissions under CD operation do not
represent the amount of work being done due to the hybrid contribution.
The EPA is thus proposing that the CS CO2 emissions must be
used to properly determine the normalized CO2 emission mass
over a 300-second test interval for off-cycle emissions. The EPA is
also proposing to revise the variable description for mCO2
in 40 CFR 1036.530(g)(1) to clarify that it is the total drift-
corrected CO2 emission mass over the test interval. Drift
correction is required for all gaseous pollutants measured during off-
cycle testing as described in 40 CFR 1065.935(g)(5)(ii). This
clarification is a reminder to the manufacturer that the CO2
emission mass over the test interval must be drift corrected.
The EPA is considering a revision to 40 CFR 1036.530(c)(3)(iii) to
allow the existing exclusion of data during an infrequent regeneration
event to include any additional time needed for emissions levels to
return to normal baseline levels. Under 40 CFR 1065.680, as amended in
the 2023 Final Rule, the EPA specified that the duration of a
regeneration event continues until aftertreatment performance and
emission levels have fully returned to normal. The EPA adopted this
change for certification because the FTP, SET, and LLC duty cycles are
relatively short and data from operation immediately following
regeneration may unrepresentatively bias measured emissions high on the
short certification cycles. In addition, 40 CFR 1065.680 is structured
to capture the emissions over the complete cycle, including operation
during regeneration and the period until the next regeneration event
occurs. As a result, defining the operation after a regeneration event
when emissions are still stabilizing as part of the regeneration does
not change the calculated infrequent regeneration adjustment factor and
mitigated concerns that post-regeneration operation would otherwise be
treated as normal baseline operation. The EPA requests comment on
whether a corresponding redefinition of the regeneration event is
warranted for off-cycle testing under 40 CFR 1036.530(c)(3)(iii). (C-
13). The EPA notes that operation subject to off-cycle test procedures
differs from certification duty cycles in that off-cycle testing spans
significantly longer durations, reducing the likelihood that post-
regeneration stabilization periods would disproportionately bias
emissions high. In fact, exclusion of this data may result in biasing
the emissions subject to the off-cycle standards low.\59\
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\59\ 40 CFR 1036.420(c) requires that Bin 1 include at least
2,400 test intervals (which is approximately 45 minutes of engine
operation) and Bin 2 include at least 10,000 test intervals (which
is approximately three hours of engine operation).
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The EPA is proposing amendments to 40 CFR 1036.545 to clarify and
improve the powertrain test procedures. The EPA is proposing to update
40 CFR 1036.545(a)(3)(i) to clarify how the transmission state (in gear
or idle) should be updated in the Greenhouse Gas Emissions Hardware-in-
the-Loop (GEM HIL) model. The update should occur in the driver
interface block. The EPA is proposing to revise 40 CFR
1036.545(a)(3)(ii) to clarify that a human driver can be used instead
of a driver model. The EPA is proposing to revise Figure 1 to paragraph
(a)(11) of 40 CFR 1036.545 by removing the appearance of ``drive idle''
and ``parked idle'' duty cycles from box 7, as they are only required
to be run for engines installed in vocational vehicles under the
existing 40 CFR 1036.535(c). Also in Figure 1, the EPA is proposing to
modify the duty cycle exceptions notes for SET, FTP, and LLC to include
notes, in addition to the existing note to disregard duty cycles in
step 7, to disregard the duty cycles in step 8 and to disregard steps
10 and 11 in their entirety. The EPA is proposing these additions in
this figure as these steps are not relevant to testing powertrains over
SET, FTP, and LLC duty cycles. The EPA is also proposing to redesignate
the paragraph that the figure resides in as 40 CFR 1036.545(a)(13).
[[Page 43176]]
The EPA is proposing to revise Equation 1036.545-4 in the vehicle
model calculations of 40 CFR 1036.545(f)(3) to clarify that cumulative
distance, Di-1, used to determine the percent grade
(Gi-1), is calculated at each time step i to determine the
cumulative distance driven from the test cycle grade profile in 40 CFR
part 1037, appendix D.
The EPA is proposing to revise 40 CFR 1036.545(j)(4) to set the
dynamometer target torque to zero when ramping to the target speed at 1
mi/hr/s. The proposed change is intended to minimize the energy used
from the plug-in hybrid battery before the CD test sequence has started
and to clarify the ramp rate. The EPA is proposing to revise 40 CFR
1036.545(j)(5) to clarify that, for plug-in hybrids, for a CD cruise
cycle test sequence, the manufacturer must transition to the next duty
cycle without altering the powertrain speed. This is because plug-in
hybrid powertrains run the same vehicle configuration for the cruise
cycles back-to-back to go from CD to CS, therefore they should not
transition to zero vehicle speed between each cruise cycle. In 40 CFR
1036.545(j)(6), the EPA proposes to remove hyphens in the term ``duty
cycle'' and clarify that the start of the next duty cycle must be
within 60 to 180 seconds after shutting off the powertrain for non-
plug-in hybrid and conventional powertrains. This is a conforming
proposed revision as the plug-in hybrid would be able to run the duty
cycles immediately per the update the EPA is proposing to 40 CFR
1036.545(j)(5).
The EPA is proposing to update 40 CFR 1036.545(m) to clarify that
the manufacturer may delete points before performing the cycle
validation when a hybrid engine is at idle. The EPA is also proposing
to clarify that when manufacturers validate the measured output speed,
they may time-align the reference and measured output speed values by
up to 0.5 seconds as described in 40 CFR 1065.514(c).
The EPA is proposing to revise Equation 1036.545-9 used to create
the GEM input for the simulated vehicle configurations in 40 CFR
1036.545(o)(3) to clarify that cumulative distance,
DCDi-1, is calculated at each test interval to
determine the cumulative distance driven under CD conditions, which is
then used to determine the utility factor.
The EPA is proposing to revise 40 CFR 1036.545(o)(4)(i) to correct
an error in the equation referenced for testing with the torque
measurement at the wheel hubs. The reference should be to Eq. 1036.545-
10 instead of Eq. 1036.545-8.
The EPA is proposing to revise 40 CFR 1036.555(a) to replace the
term ``windows'' with ``test intervals'' as the Agency believes this
term is clearer given that the 300 seconds of data that are averaged
for binning purposes constitute a test interval.
e. 40 CFR Part 1036, Subpart I--Definitions and Other Reference
Information
The EPA proposes several revisions to the definitions of 40 CFR
1036.801. The EPA proposes new definitions for the terms ``certified
configuration'' and ``useful life'' that are used throughout 40 CFR
part 1036 but not explicitly defined. The EPA proposes corrections to
the definition of ``designated compliance officer'' to reflect a recent
reorganization in the Agency's Office of Transportation and Air
Quality.
The EPA is proposing to update ASTM D975, ASTM D4809, ASTM D4814,
and ASTM D7467, that are incorporated by reference in 40 CFR
1036.810(a), to the latest versions. The EPA is also proposing to
correct existing 40 CFR 1036.810(d)(4) by adding the missing document
title for CARB's 2019 regulation ``13 CCR 1971.5'' in the incorporation
by reference entry.
f. 40 CFR Part 1036, Appendix B--Transient Duty Cycles
The EPA proposes to amend the footnotes for the transient test
intervals for spark-ignition and compression-ignition engines in
paragraphs (b) and (c), respectively, of Appendix B to 40 CFR part 1036
and the transient duty cycle for compression-ignition engines in
paragraph (d) of Appendix B to 40 CFR part 1036 to change them from
``Close throttle motoring'' to ``Minimum operator demand.'' This
proposed change would alleviate any confusion for engines that do not
have throttles. The intent of the motoring points in these test
intervals and duty cycles is to operate the engine with minimum
operator demand, which results in the throttle being closed for engines
that have throttles.
2. Proposed Revisions for Heavy-Duty Vehicles (40 CFR Part 1037)
The existing regulation at 40 CFR 1037.103 establishes evaporative
and refueling standards for heavy-duty vehicles. For vehicles using
liquefied natural gas, the existing regulation establishes hold-time
requirements to limit off-gassing of fuel by referencing SAE J2343. The
EPA is proposing to update the reference to the February 2018 version
of SAE J2343 for the hold-time requirements that apply to those
refueling systems. Also, the existing regulation specifies fuel
connection requirements for vehicles using compressed natural gas by
referencing the ANSI NGV1 standard in 40 CFR 86.1813-17. The EPA is
similarly proposing to update the reference to the version of the ANSI
NGV1 standard that was published December 2022.\60\
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\60\ See the proposed changes to the incorporation by reference
provisions in 40 CFR 1037.810 and 40 CFR 86.1.
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An earlier final rule included provisions allowing limited numbers
of qualified heavy-duty highway vehicles to have certified engines meet
alternative standards derived from the EPA's nonroad engine
programs.\61\ The provisions apply to amphibious vehicles, vehicles
with maximum operating speeds of 45 mph or less, and all-terrain
vehicles with portal axles. The provisions also apply to hybrid
vehicles with engines that provide energy for an RESS. The EPA added a
sunset clause for hybrid vehicles at the end of MY 2027 based on the
expectation that greenhouse gas standards would lead to widespread
availability of engines certified with hybrid power systems to emission
standards under 40 CFR part 1036. Once there are engines certified to
heavy-duty highway standards under 40 CFR part 1036 that meet the
design requirements of these vehicles, it will no longer be necessary
to preserve the option to use engines meeting the alternative
standards. However, the EPA's observation is that engine manufacturers
have been hesitant to pursue certification with hybrid powertrain
systems and that the available highway-certified engines are too large
for these applications, which leaves vehicle manufacturers with very
limited prospects for pursuing these specific heavy-duty highway
vehicle designs with hybrid powertrains after MY 2027. The EPA is
proposing to address this by extending the allowance to use the
alternative standards through MY 2030. At the same time, the EPA is
proposing to reduce the annual limit on the number of such vehicle
manufacturers may produce from 1,000 to 200. This change would treat
specialty vehicles with hybrid powertrains the same as the other types
of specialty vehicles. The EPA is not aware of any company having plans
to produce more than 200 heavy-duty highway vehicles with hybrid
powertrains per year that meet the qualifications in 40 CFR 1037.605.
The proposed reduction in the maximum number of covered vehicles is
intended only to avoid creating an incentive for companies to develop
new
[[Page 43177]]
plans to exploit the provision to circumvent the more stringent
standards for heavy-duty engines certified under 40 CFR part 1036. The
EPA is aware that this proposal comes at a time when it is difficult to
predict how technology and marketing developments will lead to new
availability of engines to serve vehicle manufacturers intending to
make these specific hybrid vehicles beyond MY 2027. The EPA accordingly
requests comment on the possible need to entirely remove the sunset on
alternative standards for engines installed in hybrid vehicles.
Similarly, the EPA requests comment on the need for a different limit
on the annual number of hybrid vehicles with engines certified to the
alternative standards, including maintaining the limit at 1,000. (C-
14).
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\61\ 80 FR 73478 (Oct. 25, 2016).
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The EPA is also proposing minor amendments to 40 CFR 1037.605 to
include references to the engine standards in 40 CFR part 86, subpart
A. 40 CFR 1037.605 describes how vehicle manufacturers can use engines
certified to alternative standards for certain specialty vehicles. The
EPA previously amended 40 CFR 1037.605 to refer to the alternative
standards specified in 40 CFR 1036.605. However, those alternative
standards do not take effect until MY 2027 and the proposed amendments
refer to analogous alternative standards that apply currently to heavy-
duty engines under 40 CFR 86.007-11 and 86.008-10. The EPA is proposing
to add the part 86 references to 40 CFR 1037.605 to clarify the
appropriate cross-references through MY 2026.
The EPA proposes to revise 40 CFR 1037.801 to update the definition
of ``Designated Compliance Officer'' to reflect recent Agency
reorganization.
3. Proposed Revisions for Engine-Testing Procedures (40 CFR Part 1065)
a. 40 CFR Part 1065, Subpart A--Applicability and General Provisions
The EPA proposes to clarify in 40 CFR 1065.1(e) the use of the term
``test procedures'' to include actions related to required
measurements, not just measurements related to emission standards.\62\
The EPA is proposing several revisions to 40 CFR 1065.10, which
specifies how other procedures can apply to testing. First, the EPA is
proposing to remove paragraph (d) and move the existing text into the
introductory text of paragraph (c) for clarity. The EPA proposes to
correct terminology in the introductory text of paragraph (c) for two
references to paragraphs within the section. The EPA also proposes to
revise paragraph (c)(6) to clarify that, while the regulations
generally allow manufactures to continue to use previously applicable
test procedures for up to 12 months following the effective date, the
Agency may, through a rulemaking, identify an earlier start date under
the standard setting regulations for certain changes to test
procedures, consistent with existing 40 CFR 1065.5(b). For example, the
EPA may require manufacturers to use an updated equation starting on
the effective date of a rule. The EPA proposes to revise paragraph
(c)(7) for consistency with the corresponding engine testing provisions
for recreational engines and vehicles in 40 CFR part 1051.
Specifically, existing text in 40 CFR 1051.501(g)(2) states that ``We
may reject data you generate using alternate procedures if later
testing with the otherwise specified procedures shows contradictory
emission data.'' The proposed revision would copy the text from 40 CFR
1051.501(g)(2) into 40 CFR 1065.10(c)(7) to clarify that the principle
applies universally for all sectors.
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\62\ This proposed revision is consistent with the proposed
revision to 40 CFR 1066.1(f).
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In 40 CFR 1065.10 and 1065.12, the EPA proposes to replace
references to ``alternate procedures'' with ``alternative procedures''
to be more precise. This proposed update in terminology, including for
similarly imprecise uses of ``alternate'' (e.g., ``alternate
methods''), is reflected in proposed changes throughout 40 CFR parts
1036, 1037, and 1065.\63\
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\63\ Memorandum to docket EPA-HQ-OAR-2026-0728. ``Detailed
Description of Proposal to Migrate Provisions for Nonconformance
Penalties from 40 CFR part 86, subpart L, to 40 CFR part 1071.''
June 2026.
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b. 40 CFR Part 1065, Subpart B--Equipment Specifications
The EPA is proposing to add a new 40 CFR 1065.140(b)(2)(vi) to
allow the option to measure PM background concentrations for full and
partial flow dilution sampling systems according to 40 CFR
1066.110(b)(2)(i). Currently, 40 CFR 1065.140(b) only allows
measurement of the PM background concentration from the dilution air
itself from the full-flow or partial-flow sampling system and the
measurement must be carried out simultaneously with the emissions test.
During the development of the vehicle testing procedures in 40 CFR part
1066, specifically during the light-duty vehicle Tier III rule, the EPA
promulgated PM background measurement options for vehicle testing that
could be used in addition to provisions in 40 CFR 1065.140(b).\64\
These options were to address concerns from thermophoretic wall loss
and subsequent re-entrainment of VOCs and semi-VOCs that can occur in
the sampling system during a vehicle test and carry over to other
vehicle tests. This concept is known as sampling artifact and can
result in mass contribution to the sample filter due to both
condensation of the hydrocarbons into PM and the filter materials
ability to absorb gas-phase hydrocarbons. The filter mass gain
associated with sampling artifacts could be test site-specific or
similar across multiple test sites.
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\64\ 79 FR 23829 (April 28, 2014).
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The PM background concentration measurement options that the EPA is
proposing to allow include:
1. Use of a single test-site or multi test-site derived PM
background correction using a moving-average background value if the PM
sample media were all made by the same manufacturer and material.
2. Sampling of the PM background any time before or after an
emission test provided the dilution tunnel blower is on, the vehicle is
disconnected from the laboratory exhaust tubing, and the laboratory
exhaust tubing is capped.
3. The duration of the background sample may be different than that
of the test cycle in which the background correction is being applied.
4. The PM background correction may not exceed 5 micrograms ([mu]g)
or five percent of the net PM mass expected at the standard, whichever
is greater.
Given the precedent set in the vehicle testing procedures, the EPA
proposes that it is appropriate to provide engine manufacturers with
similar relief to address PM sampling artifact associated with the
engine testing procedures. The filter loading for a heavy-duty highway
engine complying with the 2027 p.m. standard of 5 mg/hp[middot]hr,
tested in compliance with the minimum overall dilution ratio
requirements in 40 CFR 1065.140(e)(2), will be around 80 [mu]g on
average and 35 [mu]g at around 2 mg/hp[middot]hr, which is the PM
certification level expected. At 40 percent of the standard, the
maximum allowable PM background correction of 5 [mu]g would only reduce
the resulting brake-specific mass result by 14.5 percent, with a 6.5
percent effect at the standard.
c. 40 CFR Part 1065, Subpart C--Measurement Instruments
In 40 CFR 1065.225(a)(1), the EPA proposes to correct a publication
error that removed paragraph (a)(1) introductory text.
[[Page 43178]]
In 40 CFR 1065.257(d)(2), the EPA proposes to change the section
reference for H2O laser infrared analyzer (LIA) interference
verification from 40 CFR 1065.375, which is the interference
verification procedure for N2O analyzers, to a newly
proposed verification in 40 CFR 1065.358 that is specific to
H2O LIAs. Additional information on the proposed new
interference verification can be found in section of this preamble
describing changes to 40 CFR part 1065, subpart D.
d. 40 CFR Part 1065, Subpart D--Calibrations and Verifications
The EPA is proposing to revise the linearity verification frequency
for torque in Table 1 to 40 CFR 1065.303. The regulation in 40 CFR
1065.303 currently requires linearity verification of torque
measurement transducers and systems upon initial installation, within
370 days of testing, and after major maintenance. Linearity
verifications typically involve the use of a series of calibration
weights and a lever arm or use of a reference load cell or proving ring
in series. Ratings for torque meters used for testing transmissions,
axles, and large engines (e.g., a 2-megawatt engine) can be 6 to 10
kilonewton-meters (kN[middot]m) or higher. For these high-load torque
systems, in-house calibration with weights and a lever arm or a
reference load cell is not practical due to the space constraint and
the time involved in the setup. Torque systems of this capacity are
instead typically sent to the manufacturer for calibration. The
calibration can take up to six months, including shipping time. This
generally requires labs to have two sets of torque measurement systems
to avoid downtime. The linearity verification requirements are set up
to create an expectation of annual verifications. However, this
arrangement of alternating measurement systems forces a lab to do the
calibrations and then store the equipment until the calibration
approaches expiration for the alternative set of equipment. The
anticipated 370 days of testing for the calibration is typically
reduced by several months after calibration during this storage period.
This results in additional cost to the test lab. Data provided by
torque measurement system manufacturers have indicated that, for
systems or transducers sent off-site for linearity verification and
then stored in a controlled environment, there is no degradation in the
linearity for at least 185 days prior to re-entering service. To
recognize the validity of a full year of calibrated measurement from
torque measurement transducers and systems, the EPA is proposing to
delay the start of the 370-day period by up to 185 days for equipment
stored in a controlled environment. The extra time for preserving the
calibrated equipment includes time to transport the equipment, before
or after delivery to the test lab, even with no controlled environment
during shipping.
The EPA is proposing to add the H2O Fourier transform
infrared (FTIR) spectroscopy interference verification in 40 CFR
1065.357, the H2O LIA interference verification in 40 CFR
1065.358, and the ammonia (NH3) interference verification in 40 CFR
1065.377 to Table 1 to 40 CFR 1065.303 as they were accidentally
omitted from the table when these sections were added to the CFR in a
previous rule.
The EPA is proposing to revise the linearity verification frequency
for H2O LIAs in Table 1 to 40 CFR 1065.303. H2O
LIAs, which are a new analyzer type added to the CFR during a previous
rule, are required to follow the linearity verification frequency for
general gas analyzers of within 35 days before testing. H2O
FTIR analyzers are required to follow the linearity verification
frequency for FTIR analyzers within 370 days before testing. At the
time the H2O LIAs and FTIR analyzers were added to 40 CFR
part 1065, the H2O LIA was not added to the list of
analyzers that are allowed a longer verification frequency in Table 1
to 40 CFR 1065.303. The FTIR analyzers and H2O LIAs''
linearity is inherently more stable than other analyzer types. Thus,
for these reasons, the EPA is proposing to decrease the linearity
verification frequency from 35 days to 370 days before testing to put
this analyzer type on a level field with the FTIR. The EPA also notes
that since H2O analyzers were recently added to 40 CFR part
1065 to facilitate the certification of engines operating on zero-
carbon fuels, no one has certified to date using the existing procedure
that this proposed correction would revise.
The EPA is proposing to add a new 40 CFR 1065.358 to provide a
procedure to verify interference from H2O LIAs that is
specific to this type of analyzer. Under the current 40 CFR
1065.257(d)(2), which was a new section added to the CFR during a
previous rule, H2O LIAs are required to follow the
interference verification procedure in 40 CFR 1065.375 for
N2O analyzers, while H2O FTIR analyzers are
required to follow the FTIR specific procedure in 40 CFR 1065.357. At
the time 40 CFR 1065.257 was written, it was thought that the
H2O LIA could use the same verification as the
N2O analyzer. The H2O FTIR analyzer procedure was
not appropriate for H2O LIAs as CO2 is the
interference gas for FTIRs and the interference gas(es) for
H2O LIAs is dependent on the infrared absorption band.
Recently, it was brought to the EPA's attention that there are multiple
issues with requiring H2O LIAs to use the N2O
analyzer interference verification procedure. Specifically, the system
requirement (interference limit) is two orders of magnitude more
stringent for the N2O interference verification for the
H2O LIA than what is required for FTIR; 1.0 micromoles per
mol ([mu]mol/mol) (1 ppm) for N2O verification versus 0.4
millimoles per mol (mmol/mol) (400 ppm) for the H2O FTIR.
The full-scale range for both the FTIR and H2O LIAs is
greater than 30 percent, therefore, system requirement should be 0.4
mmol/mol for both analyzers. The other issue is that the interference
species are dependent on the H2O infrared absorption band
and some of the interferent species may dissolve in water. The current
required N2O interference procedure for H2O
infrared analyzers requires that the interference gases are humidified
by passing them through a bubbler. Thus, for these reasons, the EPA no
longer considers the N2O interference procedure appropriate
for the H2O infrared analyzer. This proposed new
H2O infrared analyzer interference verification procedure
would put this analyzer type on a level field with the FTIR. The EPA
also notes that since H2O analyzers were recently added to
40 CFR part 1065 to facilitate the certification of engines operating
on zero-carbon fuels, no one has certified to date using the existing
procedure that this proposed correction would revise.
The EPA is proposing to lower the tolerance on the value returned
from successive mass determinations of reference PM sample media
(filters) during reference sample weighing for the PM balance weighing
process verification in 40 CFR 1065.390(d). The process currently
requires that successive mass determinations of the reference filters
return the same value within 10 [mu]g or 10
percent of the net PM mass expected at the standard, whichever is
higher.
The 10 [mu]g tolerance is a wide range for particulate
filter-equipped engines and vehicles meeting current emission
standards. A review of some engine and vehicle manufacturer PM weigh
rooms indicated that their weighing process verification returns values
within 5 [mu]g when everything is working properly,
indicating that a tighter tolerance is warranted to dictate quality PM
weighing process practice. The EPA notes that there are still some
engine categories with PM standards that are
[[Page 43179]]
not particulate filter forcing, specifically category 1 and 2 marine
engines and locomotive engines. For these engines, a tolerance of
5 [mu]g is unnecessarily tight, as the PM standards for
these engines are generally one to two orders of magnitude higher than
passenger vehicles, heavy-duty highway engines, and nonroad land-based
engines regulated in 40 CFR parts 86, 1036, and 1039, respectively. To
address this, the EPA will maintain the inclusion of the 10
percent of the net PM mass expected at the standard option, which will
maintain a larger tolerance for category 1 and 2 marine engines and
locomotive engines.
e. 40 CFR Part 1065, Subpart F--Performing an Emission Test Over
Specified Duty Cycles
The EPA is proposing to remove references to ``electronic
integrating devices'' throughout 40 CFR part 1065, which includes
deleting 40 CFR 1065.530(b)(8), redesignating the following paragraphs,
and revising paragraphs (c)(1), (c)(2), and (c)(3). The use of
``electronic integrating devices'' predates the use of current
electronic data loggers. This step in the pre-emission sampling process
is obsolete and, therefore, the EPA is proposing to remove it.
The EPA is proposing to replace all occurrences of ``results'' with
``values'' in 40 CFR 1065.550 because the term ``values'' more closely
resembles the emissions that are being verified for drift. The EPA is
also proposing to delete all occurrences of ``brake-specific'' when
referring to drift verification as the drift verification can be done
on a brake-specific or mass per unit time (off-cycle Bin 1 testing)
basis. Removal of ``brake-specific'' will make the drift verification
procedure more universal.
f. 40 CFR Part 1065, Subpart G--Calculations and Data Requirements
The EPA is proposing to revise the variable descriptions for
Equation 1065.640-1 to better define the terms by clarifying which
variables are from the reference flow meter and which flow rates are at
standard conditions.
The EPA is proposing to revise 40 CFR 1065.642(c)(2) to replace the
variable Vstdref with Vstdref as the variable
description indicated that the term is a volume flow rate and rate
variables are denoted by an ``over dot'' in the NIST SP 811 style
guide. The EPA is also proposing to revise the variable description to
clarify that this is the standard volume flow rate output by the
critical flow venturi (CFV) constant volume sampler (CVS) flow meter at
a standard temperature and standard pressure.
The EPA is proposing to update the default CO2
background concentrations from 375 [mu]mol/mol to 428 [mu]mol/mol to
reflect the increase in background CO2, which affects the
carbon balance error verification and chemical balance calculations.
These calculations are used to determine the exhaust gas mass flow that
is needed for criteria pollutant mass emission calculations. The
updates are being proposed to 40 CFR 1065.643 for the exhaust mass flow
carbon balance error verification, Table 1 of 40 CFR 1065.655 for the
amount of intake air CO2 per mole of dry intake air and for
the amount of dilution gas CO2 per mole of dry dilution gas,
Table 1 of 40 CFR 1065.656 for the amount of intake air CO2
per mole of dry intake air and for the amount of dilution gas
CO2 per mole of dry dilution gas, and 40 CFR 1065.672 for
drift correction. This proposed updates also affect the flow meter
calibrations for CFV and subsonic venturis. Specifically, the molar
mass of dry air is used in the molar mass of exhaust calculation in
Equation 1065.640-9 of 40 CFR 1065.640, resulting in the need to update
the molar mass of dry air value to 28.96623 grams per mol (g/mol).
Updating this value results in a change of 0.002 percent when compared
to the existing value of 28.96559 g/mol. Proposing this change also
requires updating the molar mass of dry exhaust value from 28.7805 g/
mol to 28.7812 g/mol in the example problems in 40 CFR 1065.640(d)(1)
and 1065.642(b) and (c).
The EPA proposes to republish 40 CFR 1065.645(b) to improve the
publication quality of existing Equation 1065.645-3.
The EPA proposes to republish 40 CFR 1065.650(b) and (g)(2)(ii) to
improve the publication quality of existing equations.
The EPA is proposing to update 40 CFR 1065.650(d)(6) to clarify
that all power values are set to zero during idle periods with a
corresponding denormalized reference torque of 0 Newton-meters (Nm).
For test cycles like the LLC that have long idle durations in which
only accessory torque is applied, per the standard setting part, this
work is required to be included in the cycle work calculation. However,
as 40 CFR 1065.650(d)(6) currently exists, one could argue that this
work is not included because curb-idle transmission torque (CITT) isn't
applied, reference speed and torque are idle speed and 0 Nm (0 percent,
0 percent), and there is no mention of accessory load.
The EPA is proposing to update 40 CFR 1065.650(e)(2) to correct an
equation reference error. The equation to calculate mean power is
Equation 1065.650-14, but the paragraph incorrectly references Equation
1065.650-13.
The EPA proposes to republish 40 CFR 1065.655(c)(4) and (f) to
improve the publication quality of existing equations in those
paragraphs. The EPA is also proposing to revise 40 CFR
1065.655(e)(1)(i) to clarify that when verifying that the carbon,
hydrogen, oxygen, sulfur, and nitrogen mass fractions add up to a total
mass of 100 0.5 percent, normalization of the mass fraction
results to total 100 percent is not allowed. This is to address
concerns and ensure that test labs do not normalize their test results
to falsely give the appearance that the test results meet the 100
0.5 percent requirement.
The EPA proposes to republish 40 CFR 1065.650(g)(2)(ii) and
1065.656(f) to improve the publication quality of existing variables in
the text.
g. 40 CFR Part 1065, Subpart H--Engine Fluids, Test Fuels, Analytical
Gases, and Other Calibration Standards
The EPA is proposing to revise 40 CFR 1065.750(a)(6) to extend the
use of this procedure, which generates H2O calibration gases
with a humidity generator, to H2O LIAs. The paragraph, as
currently written, inadvertently limits the use to H2O FTIR
analyzers. Both of these analyzer types require the use of a humidity
generator to generate the calibration gases needed to perform the
required 40 CFR 1065.307 linearity checks.
h. 40 CFR Part 1065, Subpart J--Field Testing and Portable Emission
Measurement Systems
The EPA is proposing to remove references to ``electronic
integrating devices'' throughout 40 CFR part 1065, which includes
removing 40 CFR 1065.935(c)(1), redesignating the following paragraphs,
and revising 40 CFR 1065.935(d)(2). The use of ``electronic integrating
devices'' predates the use of current electronic data loggers. This
step in the pre-emission sampling process is obsolete and, therefore,
the EPA is proposing to remove it.
The EPA is proposing to revise 40 CFR 1065.935(g)(4)(ii) by
deleting the last sentence that provides instruction regarding data
that do not meet the drift criterion. This instruction is redundant,
already addressed by the reference to 40 CFR 1065.550 in 40 CFR
1065.935(g)(4)(ii). 40 CFR 1065.550 provides a step-by-step process for
[[Page 43180]]
validating drift and calculating emission results.
The EPA is proposing to revise 40 CFR 1065.935(g)(5)(i) to clarify
that invalidation of data for the whole shift day due to exceedance of
the overrange data limit applies only to the gas analyzer, and thus
pollutant, for which the overrange occurred (specifically CO or HC).
The EPA also proposes to revise 40 CFR 1065.935(g)(5)(i) to further
clarify that if NOX or CO2 are invalidated for
range, the data for the entire shift day for all pollutants is invalid.
The EPA is proposing to revise 40 CFR 1065.935(g)(5)(ii) to delete the
occurrence of ``brake-specific'' and to delete the last sentence that
provides instruction regarding data that does not meet the drift
criterion for the reasons explained for similar proposed revisions in
section III.D.3.h of this preamble. The EPA is also proposing to revise
40 CFR 1065.935(g)(5)(ii) to clarify that CO and HC drift is verified
as described in 40 CFR 1065.550(b)(3)(i)(A) and CO2 drift is
verified as described in 40 CFR 1065.550(b)(3)(ii)(A). The EPA is also
proposing to clarify that for the purpose of verifying drift for CO,
CO2, and HC bin testing, the test intervals are the
intervals between analyzer verifications. The EPA is also proposing to
revise 40 CFR 1065.935(g)(5)(ii) to clarify that data is invalidated
for the CO and CO2 gas analyzers if they do not meet the
drift criteria in 40 CFR 1065.550. This proposed change would alleviate
potential confusion as the 40 CFR 1065.550 drift criteria are specific
to CO and CO2 only. The off-cycle HC criterion is different
and covered in 40 CFR 1065.935(g)(5)(ii), as is the off-cycle
NOX criterion, which is covered in 40 CFR
1065.935(g)(5)(iii).
The EPA is proposing to revise 40 CFR 1065.935(g)(5)(iii) to
clarify that the data for all pollutants is invalid if the
NOX analyzer drift limits in 40 CFR 1065.935(g)(5)(iii)(A)
and (B) are not met. In 40 CFR 1065.935(g)(5)(iii)(B), the EPA is
proposing to clarify that the span value is for a gas.
The EPA is proposing to delete the occurrence of ``brake-specific''
as it refers to off-cycle emission calculations in 40 CFR 1065.940(a).
Emission calculations can be done on a brake-specific or mass per unit
time (off-cycle Bin 1 testing) basis. Removal of ``brake-specific''
will make the off-cycle emission calculations more universal.
i. 40 CFR Part 1065, Subpart K--Definitions and Other Reference
Information
The EPA is proposing to add a new definition for ``gas analyzer
range'' in 40 CFR 1065.1001 to clarify what is meant by the gas
analyzer overrange limit of one percent in 40 CFR 1065.935(g)(5)(i). By
proposing to define gas analyzer range, the EPA is clarifying on what
the one percent over range limit is based.
The EPA is proposing to revise the definition of ``oxygenated
fuels'' in 40 CFR 1065.1001 by clarifying that the fuel is composed of
at least 25 percent oxygen-containing compounds by volume. This is
consistent with the use of oxygenated fuels in 40 CFR part 1065,
subpart I.
The EPA is proposing to revise the definition of ``span'' to
clarify that it is an adjustment based on the analyzer response to a
calibration gas that is 75 to 100 percent of the range of the
instrument as opposed to the instrument's maximum value. This proposed
change is a conforming revision with the proposed addition of the new
``gas analyzer range'' definition.
The EPA is proposing to update the following ASTM methods, that are
incorporated by reference in 40 CFR 1065.1010, to the latest version
for each method: D86-23ae2, D93-20, D130-26, D381-25, D445-24, D525-
12a, D613-25a, D910-24, D975-24a, D1267-23, D1319-25, D1655-25, D1837-
17, D1838-21, D1945-25, D2158-21, D2163-23e1, D2598-21, D2622-24a,
D2699-25, D2700-23, D2713-24, D2880-23, D2986-95a, D3231-25, D3237-22,
D4052-22, D4629-24, D4814-25a, D4815-22, D5186-24, D5191-22, D5291-26,
D5453-25, D5599-22, D5762-24, D5769-25, D5797-21, D5798-25, D6348-12,
D6550-25, D6615-25, D6667-21, D6751-24, D7039-24, and F1471-09. The EPA
is proposing to incorporate by reference, in 40 CFR 1065.1010, ASTM
method E178-21, which is an outlier determination method proposed for
use in 40 CFR 1065.1121(d).
j. 40 CFR Part 1065, Subpart L--Methods for Unregulated and Special
Pollutants and Additional Procedures
The EPA is proposing a new 40 CFR 1065.1102 to provide a list of
measurement systems under 40 CFR 1065, subpart L, that require
linearity verifications using the requirements and procedures in 40 CFR
1065.307. This addresses flow rate and temperature measurement systems
in the recently added vanadium sublimation and catalyst accelerated
aging test procedures.
The EPA is proposing to revise the vanadium sublimation in SCR
catalysts test procedure in 40 CFR 1065.1113 through 1065.1121, after
receiving and considering feedback on the test procedure from labs
carrying out these tests. The proposed revisions are as follows:
1. The EPA is proposing the following revisions to 40 CFR
1065.1115:
1.1. The EPA is proposing to add a new paragraph (d) that would
allow the inclusion of an ammonia slip catalyst downstream of the
vanadium SCR catalyst in certain circumstances, specifically only in
the catalyst-coated monolith section of the reactor setup where the
ammonia slip catalyst is part of the production aftertreatment system.
Under the proposed provision, the ammonia slip catalyst must be sized
based on the highest production system volume ratio of vanadium to
ammonia slip catalyst expected. The intent of this proposed addition is
for the testing to more closely reflect how vanadium sublimation will
be affected by the presence of an ammonia slip catalyst. The EPA is
also proposing to specify that the manufacturer may use a small amount
of quartz wool between the vanadium and ammonia slip catalysts to
address catalyst core alignment, with an allowance in such circumstance
to exceed the 3-inch maximum core length in paragraph (a) of this
section by up to 2 inches.
1.2. The EPA is proposing to modify the redesignated paragraph (g)
to require measurement of vanadium, titanium, and either tungsten or
antimony above their respective detection limits if the manufacturer
wants to correct for vanadium-loaded particle contamination of the
capture bed due to physical abrasion. The proposed addition (compared
to the existing requirement) of the requirement for measurement and
detection of tungsten or antimony would provide an additional quality
check on whether the source of the titanium is abrasion from the act of
coring or handling the catalyst core, as tungsten or antimony (or both)
will be present if there is abrasion of the washcoat.
2. The EPA is proposing the following revisions to 40 CFR
1065.1117:
2.1. The EPA is proposing to revise paragraph (a) to denote that
the space velocity target is over the catalyst-coated monolith system
(which could include both vanadium and ammonia slip catalysts) and not
just the vanadium catalyst itself. The EPA is also proposing to add a
space velocity calculation and equation in paragraph (a) of this
section as paragraph (a)(1) and redesignating the following paragraph.
2.2. The EPA is proposing to revise paragraph (b) by removing the
five percent water test point. Test results using this procedure have
shown that emissions of vanadium are always higher for the 10 percent
water test
[[Page 43181]]
point versus the five percent test point as water has a significant
effect on vanadium sublimation. The EPA is proposing to eliminate the
five percent test point to streamline testing and reduce test burden,
without impacting the robustness of the testing. The EPA is also
proposing to clarify that this test point is required for diesel-fueled
engines and that for engines fueled by fuels other than diesel fuel
(e.g., spark-ignited hydrogen-fueled engines) the manufacturer must use
good engineering judgment to select an H2O volume percentage consistent
with the maximum expected exhaust H2O content for that fuel, and thus
test at a higher water content (maximum expected), as other fuels could
have higher water content (more than 10 percent) in the exhaust. The
EPA is also proposing to change the reactor temperature increase
increment from 50 [deg]C to ``up to 25 [deg]C.'' The purpose of this
change is to require labs to use shorter temperature intervals to
better capture the sublimation temperature, which will also prevent
labs from having to test at 25 [deg]C lower than the temperature at
which vanadium sublimation begins. The EPA is aware that labs may not
be able to wait for the test results to determine when sublimation
occurred and then go back and test at a point 25 [deg]C lower.
Therefore, the EPA's understanding is that most labs are testing over a
series of temperatures for a given catalyst formulation in increments
of 25 [deg]C to determine the vanadium sublimation threshold
temperature. Thus, the change the EPA is proposing more closely
reflects how labs are testing today to meet the existing provisions and
streamlines the provisions.
2.3. The EPA is proposing to revise paragraph (c) to include a new
methodology for determining the effective sublimation temperature. To
help address method detection limit (MDL) variability when determining
the MDL and actual vanadium emitted during the sublimation test, the
EPA is now proposing to require interpolation between the sublimation
temperature and next lowest temperature, in conjunction with the MDL
threshold, to determine the actual sublimation temperature.
3. The EPA is proposing the following revisions to 40 CFR
1065.1119:
3.1. The EPA is proposing to remove the requirement for analyzing
field blanks from paragraph (c) of this section as the Agency did not
provide a use for these blanks in the procedure. While the EPA does not
expect environmental contamination of the catalyst core monolith or
capture bed from the environment, any environmental contamination from
the reactor setup would be captured by the reactor blank that would
remain from the existing provisions.
3.2. The EPA is proposing to change the reactor temperature for the
reactor blank test from the average test temperature to 750 [deg]C or
the highest temperature the reactor can maintain. This would ensure
that any vanadium in the reactor system is volatilized for the reactor
blank determination. The existing provision's use of average test
temperature is problematic in that it varies for testing of different
vanadium formulations and does not provide a consistent reactor blank
temperature target. Moving to 750 [deg]C or the highest temperature the
reactor can maintain would allow a consistent temperature across all
reactor blank tests within a laboratory and would allow the blank
results to be used to maintain a rolling MDL.
3.3. The proposed addition to 40 CFR 1065.1115 to optionally test
with the ammonia slip catalyst brought to light an issue in which the
total volume of gas flow through the reactor may differ from that
during the reactor blank test when maintaining the target space
velocity of 35,000 hr-1. Testing at different volumetric flow rates
could bias the method detection limit low if the volume of gas flowed
through the catalyst coated monolith system is higher than that during
the reactor blank test. The same holds true for the method detection
limit threshold, which also scales with volume of gas flowed. To
address this, the EPA is proposing to require an adjustment to both the
lab-determined MDL from the existing 40 CFR 1065.1119(d)(1) (proposed
40 CFR 1065.1121(d)(2)) and the MDL threshold from the proposed 40 CFR
1065.1121(d)(3) via the proposed 40 CFR 1065.1119(c)(3), for which the
volumetric flow rate differs between the two tests. The adjustment
would be required to be carried out as described in 40 CFR
1065.1121(d)(4).
4. The EPA is proposing the following revisions to 40 CFR
1065.1121:
4.1. The EPA is proposing an addition to the introductory paragraph
of this section to note that this section can be used to determine the
mass of titanium, tungsten, antimony, and other elements contained in
the catalyst material in addition to vanadium.
4.2. The EPA is proposing an addition to paragraph (a) of this
section to note that all of the sample materials must be weighed prior
to sample digestion. This includes the alumina capture bed, quartz
wool, and quartz tube.
4.3. The EPA is proposing to add a new paragraph (c) to this
section that provides an equation to calculate the vanadium test
result.
4.4. The EPA is proposing to redesignate the current paragraph (c)
of this section as paragraph (d) and to remove the determination of the
reporting limit as there is no requirement to submit this to the
Agency. The EPA is also proposing to revise proposed introductory
paragraph (d) of this section to correct and replace ``average'' with
``median,'' as it is the median that is used to determine the
inductively coupled plasma mass spectrometer (ICP-MS). The EPA is also
proposing to revise redesignated paragraph (d)(1) of this section to
correct the ICP instrument detection limit units, as they were
mistakenly originally given as nanograms per liter (ng/L) and labs have
been reporting this in milligrams per kilogram (mg/kg).
4.5. The EPA is proposing to revise the redesignated paragraph
(d)(2) of this section to require that the MDL determined using at
least seven reactor blank samples is maintained by the manufacturer
using good engineering judgment to generate additional blanks and
remove old blanks as needed. The EPA is proposing to allow an outlier
check using section 7 of ASTM E178-21 to remove any data points for
which results are not consistent with the sampled reactor blanks. The
maintenance of the MDL over time can be done by maintaining a rolling
MDL, updating it by removing the oldest reactor blank results as new
reactor blank samples are taken. These proposed changes would provide
the lab with more direction and certainty on how to carry out and
maintain the MDL determination over time, as well as provide an
appropriate means to remove data from the determination that are deemed
inconsistent with respect to the historical reactor blank results.
4.6. The EPA is proposing to revise the redesignated paragraph
(d)(3) of this section to lower the MDL from an optional 15 micrograms
per cubic meter ([micro]g/m3) to a required value at or below 7
[micro]g/m3. Data generated at labs performing this test indicate that
an MDL at or below this value is readily attainable if included with an
outlier check. This also would address the concern that labs could
potentially dial in a higher MDL under the current procedure, which
equates to a higher vanadium sublimation threshold temperature during
testing. The EPA is also proposing a requirement to report the MDL at a
precision of two significant figures and to report the results and
calculated MDL at the same
[[Page 43182]]
level of precision as the threshold. The EPA is also proposing to add a
description regarding on what the 7 [micro]g/m3 threshold is based with
respect to volume flowed through the reactor, space velocity, test
duration, and catalyst core volume.
4.7. The EPA is proposing to add a new paragraph (d)(4) to this
section to provide the calculation method for correction of differences
in volume flowed during the actual catalyst test and reactor blank
test. This same calculation would also be used to adjust the MDL
threshold and the lab-determined MDL. An example problem, results, and
discussion of the results is also provided in the proposed provisions
in new paragraphs (d)(4) and (d)(5) of this section.
4.8. The EPA is proposing to expand the existing paragraph (b)(4)
of this section, which the Agency is proposing to redesignate as
paragraph (e), to provide calculations for performing correction to the
vanadium test results to account for physical abrasion of the catalyst.
Correction would be based on either the manufacturer-supplied ratio of
vanadium to titanium or the actual ratio from testing, if qualifiers
are met (ratios of co-catalysts, tungsten or antimony, as a quality
assurance/quality control check that they are within 10 percent of each
other and 20 percent of catalyst supplier provided number).
The EPA is proposing to revise 40 CFR 1065.1125(d)(2) to allow the
use of partial flow exhaust opacity measurement as an alternative to
full flow exhaust opacity measurement without Agency approval. Full
flow exhaust opacity measurement is done directly in the path of the
exhaust pipe, while partial flow is done by extracting an undiluted
portion of the exhaust for measurement in a pipe of predetermined path
length that is part of the analyzer. 40 CFR 1065.1123, 1065.1125, and
1065.1127 were developed from the nonroad exhaust opacity measurement
procedure in 40 CFR part 86, subpart I, and the locomotive procedure in
40 CFR 1033.525. Historically, partial flow exhaust opacity measurement
was allowed without EPA approval for locomotive testing in 40 CFR
1036.525 prior to migration of that portion of 40 CFR 1033.525 to 40
CFR 1065.1125. The nonroad exhaust opacity measurement procedure in 40
CFR part 86, subpart I, did not mention partial flow measurement. In
the development of the 40 CFR part 1065 procedure, the EPA
inadvertently added a clause to 40 CFR 1065.1125(d)(2) to require
Agency approval for partial flow exhaust opacity measurement systems.
The EPA is proposing to remove the requirement for Agency approval. The
EPA notes that correction of the measurement path length to account for
the difference in path lengths between the partial flow exhaust opacity
meter and the standardized exhaust path length is addressed in 40 CFR
1033.525 for locomotives and 40 CFR 1065.1127(e)(2) for everything
other than locomotives.
The EPA is proposing to revise 40 CFR 1065.1127(d)(4) to remove the
requirement to program the dynamometer to operate in torque-control
mode throughout testing. This requirement was added in error when this
procedure was migrated over from 40 CFR part 86, subpart I, as the test
would be very difficult to carry out if the dynamometer was using
torque control. The EPA is also proposing to extend the use of
dynamometer motoring assist with negative flywheel torque to the
acceleration in 40 CFR 1065.1127(d)(4)(iv). When the EPA migrated this
procedure over from 40 CFR part 86, subpart I, the Agency inadvertently
excluded this paragraph, only allowing motoring assist to be applied to
the accelerations in paragraphs 40 CFR 1065.1127(d)(4)(i) and (ii).
The EPA is proposing to revise 40 CFR 1065.1133(a)(3) and 40 CFR
1065.1139(h)(2) to clarify that manufacturers may adjust the 10-ppm
fuel sulfur rate during accelerated aging if the fuel on which the
engine operates is shown to have a sulfur level that differs from
diesel fuel. For example, under the proposed revisions, manufacturers
might alter the target fuel sulfur level if the engine is fueled on
natural gas.
The EPA is proposing to revise 40 CFR 1065.1137(d)(1)(ii)(B)(1) and
(d)(2) to revise the variable for the thermal aging rate constant, kD.
The current variable description is given as the equation for kD that
is Equation 1065.1137-5. To simplify, the EPA is proposing to reference
the section where Equation 1065.1137-5 appears (paragraph (d)(1)(ii)(A)
of that section) rather than reproduce the equation for kD each time it
appears.
The EPA is proposing to revise 40 CFR 1065.1137(d)(4)(iii)(A) to
address the variable for the thermal aging rate constant, kD. The
current variable description is given as the equation for kD that is
Equation 1065.1137-14. To simplify, the EPA is proposing to reference
the section where Equation 1065.1137-14 appears (paragraph (d)(4)(i) of
that section) rather than reproduce the equation for kD each time it
appears.
The EPA is proposing to revise 40 CFR 1065.1139(a) to clarify that
if the standard setting part does not provide the manufacturer with a
target number of useful life hours, the manufacturer must use good
engineering judgement to determine the appropriate number of hours
representing useful life based on the manufacturer's field data,
developing a metric to equate miles to hours. The EPA is also proposing
to clarify that if the manufacturer's aging of the aftertreatment
includes service accumulation hours performed on an engine dynamometer,
the manufacturer must subtract those hours, along with any engine
stabilization hours, from the useful life total prior to determining
the remaining hours needed for accelerated aging. The EPA is proposing
to correct a reference error in 40 CFR 1065.1139(b)(2)(i) as paragraph
(b)(1) is referenced, but it is not clear in what section of the CFR
the paragraph is. The EPA is proposing to correct an editorial in 40
CFR 1065.1139(b)(2)(v)(C) where variables are missing italics. The EPA
is proposing to add a reminder that if the manufacturer determines a
lower acceleration factor in 40 CFR 1065.1139(e)(6)(v), that lower
value is used in place of the default value of 10. The EPA is proposing
to update the example that is given for determining the total number of
accelerated aging hours for a Heavy HDE to better align with the
example given in 40 CFR 1036.245. The EPA is proposing to replace the
term ``alternate'' with ``alternative'' in 40 CFR 1065.1139(b)(1)(iv)
for consistency of use.
The EPA is proposing to revise 40 CFR 1065.1139(d)(1) to clarify
that the total number of regenerations during accelerated aging must be
adjusted to account for the regenerations that occurred during service
accumulations on an engine dynamometer.
The EPA is proposing to update 40 CFR 1065.1139(e)(3)(iii) and (iv)
and (g)(1) and 40 CFR 1065.1145 introductory text and paragraph (d) to
remove and replace the term ``full useful life'' with ``useful life''
as ``useful life'' is the term used throughout the standard-setting
parts.
The EPA is proposing to revise 40 CFR 1065.1141(h) and 1065.1143(h)
to clarify that the mass of ash found by DPF weight over the predicted
mass of ash based on oil consumption is a ratio range and not a range
of percent.
The EPA is proposing to revise 40 CFR 1065.1141(j) to allow sulfur
to be added directly to the fuel line that feeds the engine as one of
the options for accelerated aging for engine-based aging stands.
[[Page 43183]]
The EPA is proposing to add a new 40 CFR 1065.1143(j) to allow
sulfur to be added directly to the fuel tank or the fuel line that
feeds the burner as options for accelerated aging for burner-based
aging stands.
The EPA is proposing to revise 40 CFR 1065.1145(a)(1)(i) to provide
clarification that the NOX target level for the cycle-
average NOX mass rate is consistent with the application if
Method 1 is used to develop the accelerated aging cycle under 40 CFR
1065.1133(b) and is consistent with the weighted lab cycle
NOX measurements if Method 2 is used. The EPA is proposing
to correct a typographical error in 40 CFR 1065.1145(a)(1)(ii) by
changing ``will the be'' to ``will be the.''
The EPA is proposing to revise the recommended oxygen and water
target ranges for burner-based accelerated aging for diesel-fueled
engines in 40 CFR 1065.1145(a)(2)(i). Oxygen and water targets are not
recommended for engine-based accelerated aging under 40 CFR
1065.1145(a)(1)(i), as the oxygen and water content of the exhaust is a
product of the combustion of the fuel on which the engine is operating.
Recommended targets are needed for burner-based accelerated aging as
burner combustion can be different than engine combustion. The existing
specifications require meeting oxygen and water targets during aging
modes within 2 percent for oxygen and 2 percent
for water. The 2 percent tolerance is an error, as it should not be 2
percent of the target level or 2 percent of the allowable range in
volume percent; both of those tolerances are too narrow. The proposed
ranges provide flexibility when carrying out the aging cycle, while not
impacting catalyst aging. The EPA is also proposing to provide
clarification that the NOX target level for the cycle-
average NOX mass rate is consistent with the application if
Method 1 is used to develop the accelerated aging cycle under 40 CFR
1065.1133(b) and is consistent with the weighted lab cycle
NOX measurements if Method 2 is used. The EPA is also
proposing a NOX tolerance of 25 percent of the
target level for burner-based accelerated aging, which was previously
undefined for a burner-based platform. Adding the NOX
tolerance puts the burner-based platform on par with the engine-based
platform, which already has a NOX tolerance. However, note
that the NOX tolerance for the burner-based platform is less
restrictive because there are limitations on the amount of
NOX that the burner can produce for any given mode,
requiring undershooting of the NOX target for some modes and
overshooting at other modes. The EPA is proposing an exhaust flow
tolerance of 25 percent for individual cycle modes and a
10 percent weighted cycle average for both burner-based and
engine-based platforms to provide some assurance that the target
exhaust flows are representative and being met. The EPA is proposing to
correct a typographically error in 40 CFR 1065.1145(a)(2)(ii) by
changing ``will the be'' to ``will be the.''
The EPA is proposing to add an accelerated catalyst aging test
procedure for spark-ignition heavy-duty engine durability demonstration
as sections 40 CFR 1065.1147 through 40 CFR 1065.1155. Accelerated
catalyst aging for heavy-duty highway engines is allowed as an option
for deterioration factor determination for certifying an engine's
emissions out to its useful life in 40 CFR 1036.245. 40 CFR 1036.245
references the accelerated aging test procedures for compression-
ignition engines in 40 CFR 1065.1131 through 40 CFR 1065.1145. 40 CFR
1036.245 provides a reference to the light-duty vehicle catalyst
accelerated aging test procedure in 40 CFR part 86, subpart S, as an
example of a procedure that a manufacturer might use for accelerated
aging of heavy-duty spark-ignition engines. The EPA received requests
from heavy-duty spark-ignition engine manufacturers to add a catalyst
accelerated aging test procedure specific to heavy-duty spark-ignition
engines to 40 CFR part 1065. To address this request, the EPA is
proposing to adapt the light-duty vehicle accelerated aging test
procedure in 40 CFR 86.1823-08 for heavy-duty spark-ignition engines
and add this procedure to 40 CFR part 1065. This includes adapting
portions of 40 CFR part 86, Appendices V, VII, VIII, and IX, as
referenced in 40 CFR 86.1823-08. The new sections include a standard
catalyst bench-aging procedure that provides a means to accelerate
aging of the catalyst-plus-oxygen-sensor system on a catalyst aging
bench using the standard bench cycle. The procedure also allows the
manufacturer to develop their own bench aging procedure with EPA
approval. The migration and adjustment of this test procedure to 40 CFR
part 1065 will provide the engine manufacturers with certainty
regarding the expectations of accelerated heavy-duty spark-ignition
engine testing, while providing flexibility to the test process.
IV. Nonconformance Penalties for Diesel-Fueled Medium HDE and Heavy HDE
Under CAA section 206(g), a manufacturer is allowed to produce
engines that do not meet the applicable standards ``if such
manufacturer pays a nonconformance penalty as provided under
regulations promulgated by the Administrator after notice and
opportunity for public hearing.'' \65\ CAA section 206(g) also requires
that such regulations provide a formula to determine the NCP amounts,
and that those amounts:
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\65\ 42 U.S.C. 7525(g).
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May vary from pollutant to pollutant;
May vary by class or category or vehicle or engine;
Shall take into account the extent to which actual
emissions of any air pollutant exceed allowable emissions standards;
Shall be increased periodically to create incentives for
the development of production vehicles or engines which achieve the
required degree of emission reduction; and
Shall remove any competitive disadvantage to manufacturers
whose engines or vehicles achieve the required degree of emission
reduction.\66\
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\66\ 42 U.S.C. 7525(g)(3).
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Since the promulgation of the first NCP rule in 1985, subsequent
NCP rules generally have been described as continuing ``phases'' of the
initial NCP rule. The first NCP rule (Phase I), sometimes referred to
as the ``generic'' NCP rule, established three basic criteria for
determining the eligibility of emission standards for NCPs in any given
MY.\67\ The first criterion is that the emission standard in question
must become more difficult to meet. This can occur in two ways, either
by the emission standard itself becoming more stringent or due to its
interaction with another emission standard that has become more
stringent. Second, substantial work must be required to meet the
emission standard. The EPA considers ``substantial work'' to mean the
application of technology not previously used in that vehicle or engine
class/subclass, or a significant modification of existing technology,
to bring that vehicle/engine into compliance. The EPA does not consider
minor modifications or calibration changes to be classified as
substantial work. Third, the EPA must find that a manufacturer is
likely to be noncomplying for technological reasons (referred to in
earlier rules as a ``technological laggard''). Prior NCP rules have
considered such a technological laggard to be a manufacturer who cannot
meet a particular emission standard due to technological (not economic)
difficulties
[[Page 43184]]
and who, in the absence of NCPs, might be forced from the marketplace.
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\67\ 50 FR 35374 (Aug. 30, 1985). For existing regulatory
language,see40 CFR 86.1103-87.
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The criteria and methodologies established in the 1985 NCP rule
have since been used to determine eligibility and to establish NCPs for
a number of heavy-duty emission standards. NCP Phases II through VII,
published between 1985 and 2012,\68\ established NCPs that, in
combination, cover the full range of heavy-duty vehicles and engines--
from heavy light-duty trucks (6,000-8,500 pounds gross vehicle weight)
to the largest diesel trucks and urban bus engines. NCPs have been
established for HC, CO, NOX, and PM. The most recent NCP
rule, the Phase VII rule, established NCPs for the MYs 2012 and later
NOX standard for Heavy HDE. This proposed rule would
establish a new Phase VIII in that series of NCP rules.
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\68\ The previous NCP rules include: the Phase VII rulemaking
(77 FR 54384, Sept. 5, 2012), the Phase VI rulemaking (67 FR 51464,
Aug. 8, 2002), the Phase V rulemaking (61 FR 6949, Feb. 23, 1996),
the Phase IV rulemaking (58 FR 68532, Dec. 28, 1993), the Phase III
rulemaking (55 FR 46622, Nov. 5, 1990), the Phase II rulemaking (50
FR 53454, Dec. 31, 1985), and the Phase I rulemaking (50 FR 35374,
Aug. 30, 1985).
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Once a regulation promulgated by the Administrator after notice and
opportunity for public hearing specifies NCP provisions for a class of
engines, any manufacturer may certify engines from that class using
NCPs. Manufacturers using NCPs would go through the certification
process, submitting data showing that the engine complies with emission
standards, except that NOX emissions may exceed the
applicable standard, but can be no higher than the upper limit (UL)
established through an NCP rulemaking.\69\ Certification would
generally be contingent on performing tests in a production compliance
audit (PCA) to establish a compliance level.\70\ The compliance level
is in turn used to calculate the NCP for certifying engines with
emissions above the applicable NOX standard.\71\
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\69\ See 40 CFR 86.1106-87(a) and proposed 40 CFR 1071.15.
\70\ See 40 CFR 86.1106-87 and proposed 40 CFR 1071.30. See also
86.1112-87 and proposed 40 CFR 1071.40.
\71\ See 40 CFR 86.1113-87 and proposed 40 CFR 1071.85.
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A. NCP Eligibility
As discussed in this section, the EPA must determine that the
above-named three criteria are met to determine that an NCP should be
established in any given MY.\72\ The EPA believes these criteria have
been met for the MY 2027 NOX standard for Medium HDE and
Heavy HDE and the Agency is therefore proposing to establish NCPs.
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\72\ See 40 CFR 86.1103-2016(b).
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The first criterion is that the emission standard is more
stringent, which is the case for the new NOX, PM, HC, and CO
emission standards under the MY 2027 program.
The second criterion is that substantial work must be required to
meet the emission standard. The EPA believes that only the
NOX emission standard from the 2023 Final Rule meets the
second NCP criterion.\73\ The previous NOX emission standard
for heavy-duty engines was 200 mg/hp[middot]hr. The MY 2027 standards
are 35 mg/hp[middot]hr for NOX for the FTP and SET duty
cycles and 50 mg/hp[middot]hr for a new duty cycle that covers low-load
operation (LLC). When promulgated, the EPA concluded that the 35 mg/
hp[middot]hr NOX standard was a technology-forcing standard
because the Agency projected new technology hardware would be required
to meet the standard. For example, the EPA demonstrated that one way to
meet the MY 2027 NOX standard was equipping the engine with
cylinder deactivation (CDA), dual-SCR aftertreatment configuration,
closed crankcase, and heated DEF dosing. It is therefore logical to
conclude that substantial work is required to meet the MY 2027
NOX emission standard.
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\73\ The EPA adopted new HC, CO, and PM standards for MYs 2027
and later heavy-duty engines in the 2023 Final Rule. The EPA is not
proposing NCPs for any of these pollutants because the Agency does
not project the standards to require additional technology, since
these standards were set to prevent emissions from increasing above
the levels engines are already achieving. See section IV.B.4 of this
preamble for the HC, CO, and PM standards the EPA proposes would
apply under certain NCP scenarios.
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Third, the EPA must find that a manufacturer is likely to be
noncomplying for technological reasons. The EPA is proposing to
establish NCPs for diesel-fueled Medium HDE and Heavy HDE because the
Agency has information indicating that multiple engine manufacturers
will likely be unable to demonstrate their technology of choice will
meet the MY 2027 NOX standards for some engines in these two
engine categories by January 2, 2027 (the start of the MY). Without the
availability of NCPs, one or more engine manufacturers will be forced
to stop selling specific engine families until their development
processes are complete. This is based on multiple meetings the EPA has
had with individual engine and vehicle manufacturers over the past
year, and detailed confidential information provided by engine and
vehicle manufacturers regarding the development status of Medium and
Heavy HDEs.
B. Nonconformance Penalty Rates
The NCP rates proposed in this rule rely on the existing NCP
regulatory principles established in previous NCP rules. This section
briefly reviews the NCP rate formula originally promulgated in the
Phase I rulemaking (currently found at 40 CFR 86.1113-87) and discusses
how the EPA arrived at the NCP rates proposed in this rule.
As described in section IV.D of this preamble, the EPA is proposing
to migrate the NCP provisions from 40 CFR part 86, subpart L, to a new
40 CFR part 1071. This proposed migration is intended to retain the
primary principles established in past NCP rules while modernizing
outdated provisions, improving clarity, and harmonizing current
certification and other testing practices. The main revisions the EPA
is proposing for the NCP regulations include new cost parameters to
reflect the compliance costs for the MY 2027 standards, a new UL
relative to the MY 2027 NOX standards, and a change in the
units of the cost parameters from g/hp[middot]hr to mg/hp[middot]hr to
match the MY 2027 standards.
The proposed NCP rates are specified for MY 2027. As required in
CAA section 206(g)(3)(D), the existing regulations include a formula
that increases the NCP rates with each new MY. The EPA proposes to
apply this annual adjustment formula to the NCPs by setting the 2027 MY
as year one. Consistent with past NCP Phases, these proposed NCPs would
be available the first year of the new emission standard, which becomes
year one for purposes of the annual escalator.
As in the previous NCP Phases, the EPA is proposing five key
parameters that would be applied in the NCP formula to define the per
engine NCP for a given engine family based upon its compliance level.
First, the UL is the emission level above which no engine may be
certified. Second, the average cost of compliance (COC50) is an
estimate of the industry-wide average incremental cost per engine
(including any changes to vehicles to install these new engines)
associated with meeting the standard for which an NCP is offered,
compared with meeting the UL. Third, the 90th percentile cost of
compliance (COC90) is an estimate of the 90th percentile incremental
cost per engine associated with meeting the standard for which an NCP
is offered, compared with meeting the associated UL. Conceptually,
COC50 represents costs for a typical or average manufacturer to comply,
while COC90
[[Page 43185]]
represents costs for the manufacturers with the highest compliance
costs.\74\
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\74\ As was done in previous NCP rules, costs include additional
manufacturer costs and additional owner costs, but do not consider
certification costs because both complying and noncomplying
manufacturers must incur certification costs.
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Fourth, the average marginal cost of compliance (MC50) is an
estimate of the industry-wide average marginal cost of compliance per
unit of reduced pollutant associated with the least cost-effective
emission control technology installed to meet the new standard. In this
proposal, MC50 is measured in dollars per mg/hp[middot]hr for heavy-
duty engines. Fifth, F is a factor used to derive the 90th percentile
marginal cost of compliance (MC90) based on MC50 (the minimum value of
F is 1.1, the maximum value of F is 1.3). MC90 defines the slope of the
NCP rate curve near the standard and is equal to MC50 multiplied by F.
The derivation of the cost parameters is described in a Draft
Technical Support Document (DTSD) for this rulemaking.\75\ All costs
are presented in 2024 dollars. The DTSD also includes alternative cost
analyses that were considered, which are summarized in section IV.C of
this preamble.
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\75\ U.S. Environmental Protection Agency. ``Amendments and
Nonconformance Penalties for Model Year 2027 and Later Heavy-Duty
Highway Engines and Amendments to Inducement Provisions for SCR-
Equipped Diesel Engines: Draft Technical Support Document--
Nonconformance Penalty Analysis''. June 2026. EPA-420-D-26-003.
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1. Upper Limit
As described below, the EPA is proposing the UL for NOX
for this NCP rule at 200 mg/hp[middot]hr, which is the level of the
NOX standard that applies to MYs 2026 and earlier heavy-duty
engines. The UL is the emission level established by regulation above
which NCPs are not available and a heavy-duty engine cannot be
certified or introduced into commerce. CAA section 206(g)(2) refers to
the UL as a percentage above the emission standard, set by regulation,
that corresponds to an emission level the EPA determines to be
``practicable.'' The UL is an important aspect of the NCP regulations
not only because it establishes an emission level above which no engine
may be certified, but it is also a critical component of the cost
analysis used to develop the NCP rates. The regulations specify that
the relevant costs for determining COC50 and
COC90 are the differences between an engine at the UL and
one that meets the applicable standards (see existing 40 CFR 86.1113-87
and the proposed new 40 CFR 1071.80 that would apply to MYs 2027 and
later engines).
Under the Phase I rulemaking, the EPA concluded that the UL should
be reasonably achievable by all manufacturers with engines in the
relevant class.\76\ Setting an UL below the standard that applied
before the new standard is in effect may lead a manufacturer to invest
in intermediate technologies, when the manufacturer could instead
direct its resources and additional lead time offered by NCPs to
developing a fully compliant engine. Similarly, a manufacturer of a
previously certified engine or vehicle should not be forced to
immediately remove a heavy-duty engine or vehicle from the market when
an emission standard becomes more stringent. The prior NOX
emission standard meets these goals because manufacturers have already
certified their vehicles to that standard.
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\76\ 50 FR 35374 (Aug. 30, 1985).
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Manufacturers are currently certifying all of their engines at or
below the 200 mg/hp[middot]hr NOX standard. Thus, the EPA is
proposing the UL for this NCP rule at 200 mg/hp[middot]hr
NOX. This will conform to the purpose of NCPs, which is to
allow manufacturers to continue selling engines they are currently
producing while developing engines which meet the new standard.
2. General Methodology
Based on the available data, the EPA has determined that the best
methodological approach for this proposal is to rely on the approach
the Agency took in the 2023 Final Rule to determine the incremental
technology needed to meet the MY 2027 standards. The EPA selected a
baseline engine technology package that would employ the same basic
emission controls used to meet the MY 2026 NOX and PM
emission standards, which includes exhaust gas recirculation, optimized
turbocharging, optimized fuel injection, diesel oxidation catalysts,
DPFs, and liquid urea-based SCR with a single dose. For estimates of
COC50 and COC90 for NCPs in this proposal, the
EPA assumes a technology package that includes an engine equipped with
CDA, dual-SCR aftertreatment configuration, closed crankcase, and
heated DEF dosing systems, consistent with the technology package used
in the Agency's feasibility demonstration and cost projections for the
2023 Final Rule. In this proposal, the EPA estimated
COC50and COC90 using component cost data from the
2023 Final Rule's technology cost teardown study of the aftertreatment
systems of an engine meeting MY 2026 standards and one designed to meet
the MY 2027 standards. As described in the DTSD for this proposal, the
EPA believes estimating the NCPs based on public data that the Agency
has already released through a notice and comment process is a
reasonable basis upon which to determine compliance costs. The EPA is
requesting comment on other data sources and alternative methodologies
based on other technology packages manufacturers are developing to meet
the MY 2027 standards. (C-15).\77\
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\77\ See section IV.C.4 of this preamble.
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A key element of the NCP cost parameters is COC90, which
defines the maximum NCP for engines emitting at the UL. Figure IV-1 is
an illustrative figure of an NCP NOX curve for MY 2027.
[[Page 43186]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.006
The NCP for engines at the UL would be equal to the EPA's estimate
of the highest marginal cost paid by a complying manufacturer for
reducing NOX emissions from 200 mg/hp[middot]hr to 35 mg/
hp[middot]hr. If the EPA estimates that marginal compliance costs
change as the compliance level approaches the standard, COC50 would
define the point on the curve at which the slope changes. For this
proposal, the EPA calculated COC50 using the direct manufacturing
costs, updated to 2024 dollars, from the 2023 Final Rule's projected
technology package, which included aftertreatment catalyst volumes for
engines representing average displacements within each of the Medium
HDE and Heavy HDE categories. The EPA calculated COC90 using
the same cost methodology for COC50, but with the
aftertreatment catalyst volumes increased to match the largest
displacement Medium HDE and Heavy HDE for each category. This resulted
in a roughly 33 percent and 13 percent increase in the catalyst and
canning costs for Medium and Heavy HDE, respectively.
In addition to using the direct manufacturing costs to estimate
COC50 and COC90, the EPA includes the indirect
costs and the incremental lifetime DEF consumption. For the indirect
costs, the EPA relied on the retail price equivalent (RPE) factors used
in the 2023 Final Rule. See Table IV-1 for these RPE factors.
[GRAPHIC] [TIFF OMITTED] TP14JY26.007
To estimate the incremental lifetime DEF consumption, the EPA
relied on the 2023 Final Rule's analysis that estimated lifetime DEF
consumption for each MOVES vehicle type and regulatory class. For this
analysis, the EPA created a single cost for each MOVES regulatory class
by using a population-weighted average of each MOVES vehicle type.
Lifetime costs were determined using a 7 percent discount rate, which
the EPA expects to match how the heavy-duty industry considers future
costs. The lifetime DEF costs for Medium HDE and Heavy HDE were
estimated to be $433 and $2,041, respectively, in 2024 dollars.
To estimate MC50, the EPA assumed use of a less cost-
effective emission control technology to reduce NOX
emissions from 65 mg/hp[middot]hr to 35 mg/hp[middot]hr. Reducing
emissions by the last 30 mg/hp[middot]hr requires a technology that can
raise the exhaust temperatures under
[[Page 43187]]
low-load and cold-start operation. For the 2023 Final Rule, this level
of emissions reduction was achieved by a combination of equipping the
engine with cylinder deactivation and raising the engine idle speed. An
alternative technology would be to install an electric exhaust heater
with a 48-volt (V) generator (e-heater). Since the incremental cost for
an e-heater is greater (i.e., less cost-effective) than the costs of
CDA and engine calibration, the EPA used the cost of the e-heater
system to determine MC50. In addition to basing
MC50 on the incremental direct and indirect manufacturing
costs, the EPA also estimated the incremental increase in DEF needed to
reduce NOX from 65 mg/hp[middot]hr to 35 mg/hp[middot]hr.
The F factor is defined in existing 40 CFR 86.1113-87(a)(4) and in
the proposed new 40 CFR 1071.80(a) as the ratio of MC90 to
MC50. To estimate the F factor, the EPA proposes to use the
ratio of COC90 to COC50, which reasonably
approximates the increase in MC90 over MC50 since
the EPA expects the marginal cost of compliance to scale with the
absolute cost of compliance. With this approach, the F factors for
Medium HDE and Heavy HDE are 1.176 and 1.093, respectively. Consistent
with the existing and new proposed definitions that limit F to values
between 1.1 and 1.3, the EPA proposes to round the F factor for Heavy
HDE up from 1.093 to 1.1. The EPA requests comment on whether the F
factor should be rounded to 1.1 or should be kept at 1.093. (C-16).
3. Proposed NCP Parameter Values and Resulting Penalties
In this action, the EPA proposes to specify that the values in
Table IV-2 be used in the NCP formula for the MYs 2027 and later
NOX standard of 35 mg/hp[middot]hr for Medium HDE and Heavy
HDE. The complete derivation of these parameters is described in the
DTSD for this proposal. The EPA requests comment on the Agency's
estimates of these parameters (C-17).
[GRAPHIC] [TIFF OMITTED] TP14JY26.008
The proposed calculation parameters in Table IV-2 are used to
calculate the NCP rate. These parameters are used in the NCP rate
formulas, which are defined in the existing 40 CFR 86.1113(a) and
proposed new 40 CFR 1071.85. Using the parameters in Table IV-2, the
EPA plotted NCP rates versus compliance levels in Figure IV-2 and
Figure IV-3 for Medium HDE and Heavy HDE, respectively.\78\ The
vertical dashed lines in Figure IV-2 and Figure IV-3 are at the
emissions levels defined by the variable ``X'' where the NCP is equal
to COC50. Manufacturers would calculate a per-engine NCP for
an NCP family depending on whether the compliance level is above X or
at or below X. Using the proposed parameters in Table IV-2, X equals
78.5 mg/hp[middot]hr and 103.8 mg/hp[middot]hr for Medium HDE and Heavy
HDE, respectively. These NCP curves are for the first year of use of
the NCPs (i.e., the annual adjustment factors have been set to one).
The existing NCP rate formulas are designed so that the NCP is lower as
compliance level approaches the standard. For example, if a MY 2027
Heavy HDE engine family had a NOX compliance level of 100
mg/hp[middot]hr, under the proposal, the per engine NCP would be
$5,875. For a MY 2027 Heavy HDE engine family with a NOX
compliance level of 45 mg/hp[middot]hr, under the proposal, the per
engine NCP would be $904. For MY 2027 Medium HDE engine families with
the same NOX compliance levels of 100 mg/hp[middot]hr and 45
mg/hp[middot]hr, the proposed per-engine NCPs would be $3,799 and $851,
respectively.
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\78\ The compliance level is determined from the production
compliance audit, which consists of testing three to 24 engines (see
existing 40 CFR 86.1112-87 and the proposed new 40 CFR 1071.40 that
would apply to MYs 2027 and later engines).
---------------------------------------------------------------------------
CAA section 206(g)(3)(E) requires that the NCP be set at such a
level that it removes any competitive disadvantage to a complying
manufacturer.\79\ The EPA 1985 NCP Phase I rule developed a generic NCP
curve designed to remove any competitive disadvantage to the complying
manufacturers, with the specific values to be determined via rulemaking
for the specific emission standards and engine service class for which
the NCPs are being established. The methodology for developing the NCPs
is detailed in section IV.B.2 of this preamble and the DTSD for this
proposal. Consistent with previous NCP rules, the EPA's projection for
the cost to comply with the MY 2027 standards includes the change in
technologies, calibration changes, and increased use of DEF, all of
which are elements based on the projected costs of the 2023 Final Rule
(adjusted for inflation) and representative of the cost to comply with
the MY 2027 standards. For these reasons, the EPA believes that the
NCPs proposed in this rulemaking would remove any competitive
disadvantage that complying manufacturers may face.
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\79\ 42 U.S.C. 7525(g)(3)(E).
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[[Page 43188]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.009
[GRAPHIC] [TIFF OMITTED] TP14JY26.010
4. Proposed NCPs for Engines Certified Under 40 CFR Part 86
In the 2023 Final Rule, the EPA made comprehensive changes to
certification requirements beyond lowering the numeric values of the
NOX standards. In addition to the useful life and warranty
provisions the EPA is proposing to change in this action, the 2023
Final Rule also added a new LLC and updated the off-cycle test
procedure for engines certified as Light, Medium, and Heavy HDE. The
2023 Final Rule made several changes to update OBD requirements and to
improve the serviceability of new engines, making it easier for owners
and operators to repair their trucks. The 2023 Final Rule also lowered
the HC, CO, and PM standards. Although not projected to require
additional
[[Page 43189]]
technology, these standards were set to prevent emissions from
increasing above the levels engines were already achieving. The new
requirements were added to 40 CFR part 1036, whereas the MYs 2026 and
earlier requirements are in 40 CFR part 86, subpart A.
If a manufacturer has not completed the development of their
engines for MY 2027, NCPs are needed to carry over MY 2026 engine
families into MY 2027. The EPA proposes allowing this carryover with
NCPs because the additional requirements in 40 CFR part 1036 require
additional engine development, which manufacturers may not have time to
complete for these carryover engines that they were planning to retire
before the start of MY 2027. Since the main purpose of NCPs is to
provide a path for manufacturers to stay in the market with
noncompliant engines, the EPA is proposing an option to carry over MY
2026 engines. Under the proposed new 40 CFR 1071.80(d), manufacturers
would be allowed to certify an engine family under 40 CFR part 86,
subpart A, but would be assigned a compliance level at the UL and the
maximum NCP would apply.\80\ The EPA considers this to be reasonable
because the Agency projected that additional technology and calibration
would be needed to control emissions under the broader range of
operation covered by the certification requirements in 40 CFR part
1036, compared to 40 CFR part 86. This additional technology and
calibration would result in greater compliance costs and NOX
reductions than are reflected by just those families' NOX
levels on the FTP and SET. The proposed approach is consistent with the
provisions of the 2023 Final Rule, which discounted NOX
credits by 40 percent for engine families certified to 40 CFR part
86.\81\
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\80\ As discussed in preamble section IV.B.3, for engine
families that are certified to the requirements in 40 CFR 1036, the
NCP is determined by the compliance level of the engine family.
\81\ See 40 CFR 1036.150(a)(1).
---------------------------------------------------------------------------
Under this approach, the EPA is proposing that a separate NCP would
not be required for the HC, CO, and PM standards. The NCP at the UL
would cover the total cost difference in compliance between engine
families meeting the 35 mg/hp[middot]hr standard and engine families
certified under 40 CFR part 86.
This approach would also allow manufacturers to carry over their
engine families certified under 40 CFR part 86 without having to meet
the additional certification requirements in 40 CFR part 1036, such as
OBD and serviceability requirements. The EPA is proposing that
manufacturers demonstrate compliance with phase-in and testing
requirements in 40 CFR 1036.110, excluding engine families certifying
to OBD requirements in 40 CFR part 86. The EPA is also proposing to
allow manufacturers to continue to use approved deficiencies through
model year 2029. These are important considerations because it is
likely that these engines would not be able to comply with the EPA's
revised OBD program, for example due to the significant hardware and
software changes needed to meet in-cab display requirements. The EPA is
requesting comment on whether the Agency should consider modifying
additional OBD provisions to accommodate the certification of engines
to the proposed NCP requirements. (C-18).
For these carryover engine families certified under 40 CFR part 86,
the EPA is proposing to provide some relief by not requiring PCA
testing and, instead, the engine family would be assigned a compliance
level of 200 mg/hp[middot]hr. The EPA believes this compliance level is
justified because PCA testing would not reduce the NCP for these
families. In addition, these carryover engine families have already
been certified to meet the 200 mg/hp[middot]hr NOX standard.
C. Other Considerations for MY 2027 NCPs
1. Alternative Technology Package for Developing MY 2027 NCPs
As discussed in section IV.B of this preamble, the proposed NCPs
are based on one technology package capable of meeting the MY 2027
NOX standard--dual SCR technology with a close-coupled (CC)
SCR catalyst combined with cylinder deactivation. The EPA recognizes
there are other technology packages that some firms likely will use to
achieve the MY 2027 NOX standard. Other technology packages
may have a different incremental cost impact, which could affect the
estimated NCPs. One technology path of which the EPA is aware is an e-
heater system. For this proposal, in addition to the primary
methodology for developing the proposed NCPs, the EPA also developed an
estimate of NCPs based on the use of e-heater systems to meet the MY
2027 NOX standard. With this e-heater technology package,
the e-heater system replaces the CDA hardware and the CC SCR catalysts,
CC DEF doser, and CC mixer. The e-heater technology package also
requires a power generation source (a 48-V generator) and supporting
technology (a DC-DC convertor and a cooling system). To estimate the
cost of the e-heater, 48-V generator, DC-DC converter, and cooling
system, the EPA relied on a study conducted by the International
Council on Clean Transportation (ICCT) in 2021 to estimate the
technology costs to meet Euro VII standards.\82\ The EPA is not basing
the proposed NCP parameters on a technology package with an e-heater,
as the Agency only has one publicly citable source for a cost estimate
for the e-heater systems, which has not gone through a public comment
process and it is unclear if that source has been peer reviewed.
Nevertheless, the EPA presents an estimate of NCPs based on the e-
heater technology package in the DTSD for this proposal. The EPA
requests comment on whether to rely on an e-heater technology package
and requests references to other publicly available data for the
components of such a system. (C-19).
---------------------------------------------------------------------------
\82\ Ragon, P., Rodriquez, F. (2021). Estimated cost of diesel
emissions control technology to meet future Euro VII standards,
https://theicct.org/wp-content/uploads/2021/06/tech-cost-euro-vii-210428.pdf.
---------------------------------------------------------------------------
In several previous NCP rules, the EPA relied on CBI from
manufacturers to inform the NCP parameters. However, the EPA does not
have sufficient information at the time of this proposal to use this
approach. Nevertheless, if in response to this proposal the EPA
receives CBI cost data from manufacturers (e.g., suppliers, engine
manufacturers, or vehicle manufacturers), the Agency will consider that
information in the development of the final rule.
2. Methodology for Determining MC50 and MC90
As discussed in section IV.B.2 of this preamble, the EPA determined
MC50 based on the technology needed to reduce emissions from 65 mg/
hp[middot]hr to standard of 35 mg/hp[middot]hr, which is consistent
with the approach taken in previous rules of determining the marginal
cost of compliance based on the incremental cost to reduce an increment
of emissions near the standard. However, in the Phase VII rulemaking,
the EPA determined MC50 by dividing COC50 by the difference in
emissions from the upper limit and the standard, and MC90 by dividing
COC90 by the difference in emissions from the upper limit and the
standard.\83\ The approach of determining MC90 based on the marginal
cost between the upper limit and the standard would result in slopes of
NCP versus compliance level that are constant at $22 mg/hp[middot]hr
and $38 mg/hp[middot]hr for Medium and Heavy HDE, respectively. Figure
IV-4 shows how the proposed NCP curve would
[[Page 43190]]
change for Heavy HDE if the EPA were to take this approach. The EPA
requests comment on using this approach for the final rule. (C-20).
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\83\ Phase VII rulemaking (77 FR 54384, Sept. 5, 2012).
[GRAPHIC] [TIFF OMITTED] TP14JY26.011
3. Inclusion of Other Costs in NCPs
For this proposal, the EPA did not include local and State sales
tax or Federal excise tax in the NCP calculation. The EPA expects that
at least some portion of the NCPs will be passed on to the customer in
the final vehicle price, which will be taxed as applicable. The EPA
requests comment on this approach. (C-21).
For this proposal, the EPA included lifetime DEF costs in the NCP
values using a 7 percent discount rate. This approach is consistent
with other NCP rules in which the EPA included lifetime fuel and DEF
costs.\84\ NCPs must be set at a level to remove any competitive
disadvantage for complying manufacturers, but they are not intended to
unduly penalize noncomplying manufacturers. Considering the need to
balance these two requirements, the EPA requests comment on
alternatively including DEF costs for only the initial two to four
years of an engine's life instead of the full lifetime costs. (C-22).
---------------------------------------------------------------------------
\84\ For example, in the Phase VII rulemaking (77 FR 54384,
Sept. 5, 2012) the EPA included lifetime DEF and fuel costs.
---------------------------------------------------------------------------
Regarding the indirect costs, the EPA relied on the RPE values for
the ``heavy-duty truck industry,'' which is consistent with how the
Agency estimated the indirect costs in the 2023 Final Rule.\85\ The EPA
requests comment on this approach. (C-23). An alternative to this
approach would be to use the indirect costs for heavy-duty engine or
vehicle manufacturers as shown in Table IV-3. The use of the indirect
costs for the heavy-duty truck manufacturer could be justified if it is
appropriate to assume that the markup for the truck dealers will
include a markup on the NCP.
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\85\ These retail price equivalent factors were included in
Tables 7-13 of the 2023 Final Rule RIA. See Control of Air Pollution
from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards,
Regulatory Impact Analysis. December 2022. EPA-420-R-22-035.
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[[Page 43191]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.012
4. Alternative Methodologies for Determining Annual Adjustment Factor
This proposed rule includes the equations from 40 CFR part 86,
subpart L, for calculating and applying the Annual Adjustment Factor
(AAF) to determine NCP values. The AAF includes a term to increase NCP
values over time, with the goal of preventing manufacturers from
relying on NCPs as a long-term compliance strategy. The AAF equation
accounts for this by including a years counter, i, as an exponent on
the factor characterizing the fraction of the engine fleet certified
using NCPs. The calculation applies much like a calculation of
compounding interest over several years. This has the effect of
applying the AAF from a given year as if it has been in place every
year that NCPs have been available.
[GRAPHIC] [TIFF OMITTED] TP14JY26.013
Where:
Ii-1 = The fractional value representing the increase in overall
consumer price index in year (i-1), as described in 40 CFR 86.1113-
87 and in the proposed 40 CFR 1071.85.
Ai = The usage adjustment factor in year i: Let Ai = 0.08, except
that A1 = 0 and A2 = 0.10.
fraci-1 = The fraction of vehicles or engines in a class that are
certified using NCPs in the year before the current year i, as
described in 40 CFR 86.1113-87 and in the proposed 40 CFR 1071.85.
If fraci-1 is above 0.50, calculate AAFi using fraci-1 = 0.50.
In 40 CFR 86.1113-87 and in the proposed 40 CFR 1071.85, there is
no AAF for the first year but the factor with the exponent applies the
adjustment to the second year as if it applied to both years. Another
complicating factor is that the NCP equation requires calculating a
base NCP value for the first year and then multiplying by the product
of past and current AAFs. This approach applies additional compounding
on top of the compounding incorporated into the calculation of the AAF.
Separate from inflation and without the inclusions of the exponent, the
largest AAF (for which half of the engines from the class use NCPs in
the previous year) is 1.2. Including the exponent (i = 2) in the AAF
calculation causes the value of the NCP to increase by 40 percent in
the second year. For the third year (still with half the engines from
the class using NCPs in the previous year), the AAF equation would
increase the NCP by a compounded factor of 1.64 (a 64 percent
increase). Multiplying the three AAF together would cause the NCP for
the third year to increase by 130 percent (1 x 1.40 x 1.64 = 2.30). The
AAF of 2.28 for the fourth year would lead to more than a five-fold
increase in the value of the NCP. This scenario, for which 50 percent
of the engines in a class continue to use NCPs over multiple years, is
unlikely and this effect would be much less dramatic as the fraction of
the fleet needing NCPs approaches zero. Nevertheless, this calculation
methodology accelerates the increasing NCP values over time beyond what
would apply based on compounding calculations.
The EPA requests comment on retaining the existing exponent and on
two options to change the Agency's historical approach. Retaining the
existing exponent would provide the most motivation for manufacturers
to meet the standards in later years instead of using NCPs. If it is
likely that manufacturers will continue to need additional time to meet
the standards for a large fraction of the engines in a class, another
option could be to remove the exponent from the AAF calculation,
resulting in a standard compounding rate that would avoid the NCPs
becoming cost-prohibitive to the point that certifying with NCPs is no
longer a marketable option. A second option could be to replace the
exponent ``i'' with ``i-1,'' which would apply some accelerated
compounding and aligns the calculations with the existing approach of
not having an AAF for the first year. The EPA requests comment on these
potential alternative approaches. (C-24).
5. Use of Credits and NCPs in the Same Engine Family
In the proposed new 40 CFR 1071.15(b), the EPA is proposing to
migrate the Agency's longstanding policy that engines may exceed
emission standards using either emission credits or NCPs, but never in
combination.\86\ Specifically, this proposed provision would continue
to require manufacturers to isolate engines using NCPs into NCP
families that are separate from a manufacturer's averaging sets to
simplify the implementation and clearly distinguish which compliance
provisions apply to a given engine family. The EPA expects
manufacturers would continue to use emission credits that are available
before using NCPs. The proposed text notes that manufacturers might be
able to use emission credits to delay their initial use of NCPs until
well after the start of MY 2027, and manufacturers would also have the
option to separate an existing engine family into one that would use
credits and one that would use NCPs to comply with the standards.
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\86\ See 40 CFR 86.004-15(g).
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The EPA's 1990 final rule that established banking and trading for
NOX emissions included a discussion of the
[[Page 43192]]
interaction of NCPs and ABT.\87\ To prevent manipulation of the NCP and
ABT programs, the EPA finalized that credits could not be generated by
a single family for which NCPs are used or any engine families in an
averaging set for which NCPs are used. To avoid any program design
complications caused by simultaneous NCP and credit use by a family,
the 1990 rule required an engine family needing both NCPs and credits
to meet the emission standard to be separated into two families. One
family would strictly use credits, be assigned an FEL, and involve only
the number of engines that can be certified to the emission standard
using the credits available. The other family would strictly use NCPs
and be comprised of the remainder of the engines in the original engine
family. The 1990 rule noted that the manufacturer would assign the
number of engines to each family (as available credits allow) to always
ensure a compliance with the standard and, thus, to provide a means of
quick remedy of any noncompliance, since future production could be
shifted to the NCP family. Consistent with this historical approach,
the proposed new 40 CFR 1071.15(b) includes a similar restriction on
using credits and NCPs in the same family and the EPA proposes to use
the term ``NCP families'' throughout the proposed new 40 CFR part 1071
for a clear distinction.
---------------------------------------------------------------------------
\87\ 55 FR 30604 (July 26, 1990).
---------------------------------------------------------------------------
The EPA notes that the proposal to the 1990 rule considered a
general guideline that use of credits provides an air quality benefit
compared to use of NCPs, since the higher emissions from NCP engines
are not offset by correspondingly lower emissions from other engine
families. Using that guideline, the EPA proposed that any manufacturer
that desires to pay NCPs for an engine family that has credits
available for use in that averaging set would lose all of these
available credits.\88\ That proposal was intended to optimize
environmental benefits by incentivizing manufacturers to use their
available credits before paying NCPs. However, the EPA did not finalize
that restriction, noting that those credits could be used to offset
noncompliance in other engines or remain banked with no environmental
disbenefit.
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\88\ 54 FR 22680 (May 25, 1989).
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In this proposed rule, the EPA is requesting comment on allowing
manufacturers to use NOX emission credits in the NCP program
to lower the penalty with the benefit of offsetting NOX
emissions from higher-emitting NCP engines. The EPA recognizes that
doing so would be a change in Agency position. However, a manufacturer
could reduce the NCP for a given engine family if NOX
credits could be applied to that engine family to lower the effective
compliance level from which the NCP is calculated. The EPA believes
there would also be an emissions benefit from this approach, as a
manufacturer could offset a portion of the emissions above the standard
from an NCP engine with banked NOX emission credits earned
from engines which performed at a level below the NOX
standard, and those emission credits would no longer be available to
offset future credit-using engine families. The EPA notes there would
be an additional reporting and recordkeeping burden, for both the
manufacturer and the Agency, associated with tracking credit use in
addition to the proposed NCP provisions. The EPA requests comment on
allowing NOX emission credits to be used in the NCP program,
including any competitive concerns, environmental impacts, and
reporting and recordkeeping burdens. (C-25). The EPA also requests
comment regarding how NOX credits may impact the statutory
requirements that NCPs ``shall take into account the extent to which
actual emissions of any air pollutant exceed allowable emissions under
the standards . . .'' and that NCPs ``shall remove any competitive
disadvantage to manufacturers whose engines or vehicles achieve the
required degree of emission reduction.'' Finally, the EPA requests
comment on any interaction with the credit flexibilities request for
comment in section III.D of this preamble.
D. Migrating Regulation to 40 CFR Part 1071 and Proposed Revisions to
the Regulation
The EPA first adopted regulations in 1985 to establish NCP
provisions at 40 CFR part 86, subpart L.\89\ Several subsequent
rulemakings established new NCP provisions for specific emission
standards and classes of engines or vehicles, with various amendments
to the program structure along the way. This proposed rule provides an
opportunity to clarify and improve the wording of the existing NCP
regulations in plain language and with improved organization. In this
rule, the EPA is proposing to migrate the NCP provisions to a new 40
CFR part 1071 as described in this section.
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\89\ Phase I rulemaking (50 FR 35374, Aug. 30, 1985).
---------------------------------------------------------------------------
Consistent with this migration, the proposed provisions discussed
in this section refer to the proposed regulations in their proposed new
location in 40 CFR part 1071. In general, this migration is not
intended to change the NCP program previously specified in 40 CFR part
86, except as specifically proposed in this rulemaking. The proposed 40
CFR part 1071 accordingly sets up provisions to establish the general
construct of the program to allow noncompliant heavy-duty engines and
vehicles to pay NCPs instead of meeting current standards. The full
scope of NCP provisions includes heavy-duty engines certified under 40
CFR part 1036 and vehicles above 6,000 pounds GVWR certified under 40
CFR part 86, subpart S. This proposed rule includes specific NCP
provisions only for certain heavy-duty engines relative to the 2027
NOX standard, as described in this section IV.
While the EPA is proposing extensive wording changes in some cases
to achieve more plain language, the goal in drafting most of the
proposed text for 40 CFR part 1071 is to preserve the overall structure
and function of the program. The proposed new regulation at 40 CFR part
1071 makes improvements in four broad areas. First, the EPA is
proposing several minor adjustments to modernize the regulation. For
example, the proposal specifies how to make electronic payments through
www.pay.gov since the Federal government no longer accepts payments
with paper checks. The EPA has also updated emission calculation
instructions to include infrequent regeneration adjustment factors and
reference 40 CFR part 1066 for vehicle-testing procedures.
Second, the proposed regulation streamlines descriptions,
eliminates obsolete content, and moves historical NCP information to an
appendix. The overall effect of these drafting changes is to reduce the
length of the regulatory text by about half.
Third, the EPA carefully reviewed the provisions at 40 CFR part 86,
subpart L, and found several ways to improve clarity and address
various ambiguities of the existing program. Some examples of these
ambiguities include: (1) Determining the relationship between emission
credits and NCPs, (2) understanding the possible scenarios for starting
and discontinuing NCPs, (3) deciding which configurations to include in
PCAs, (4) determining the AAF and other aspects of the NCP calculation,
and (5) identifying how many engines are subject to NCPs in a given
calendar quarter.
Fourth, the EPA harmonized the regulation with similar provisions
that already apply to certification testing and selective enforcement
audits. For example, the EPA and the regulated
[[Page 43193]]
industries have many years of experience implementing existing
compliance provisions in other parts, including test orders, pass-fail
determinations, instructions for preparing test engines, reporting and
recordkeeping for test data, Agency entry and access to a
manufacturer's testing facility, and handling of CBI. The proposed
regulation at 40 CFR part 1071 includes several references to these
other existing provisions. In other cases, the EPA copied text into the
proposed 40 CFR part 1071 with minor adjustments to fit the NCP
context.
The following examples illustrate how the proposed regulation at 40
CFR part 1071 expands on the existing regulation under 40 CFR part 86,
subpart L, to either remove ambiguity or adjust regulatory provisions:
Section 1071.15(b): Clarifying that engines may exceed
emission standards using either emission credits or NCPs, but never in
combination. See section IV.C.5 of this preamble for a discussion of
other approaches the EPA is considering. Section 1071.30: Existing 40
CFR 86.1106-87(a)(2) specifies that PCA testing must be conducted on
the same configurations that exceeded the standards in certification
but that the EPA may approve testing more or fewer configurations.
Also, existing 40 CFR 86.1110-87(a) describes a process of the EPA
giving manufacturers instructions for selecting specific engines for
PCA testing. The proposed new 40 CFR 1071.30 specifies that the
compliance level from PCA testing would apply to the whole NCP family,
unless the manufacturer chooses to divide the family into subfamilies
to establish separate compliance levels for groups of engine
configurations. The proposed new 40 CFR 1071.30 also refers to a
proposed new 40 CFR 1071.35, which describes a plan for the EPA to send
instructions to manufacturers analogous to a test order for a selective
enforcement audit. Considering that the compliance level serves as the
emission standard for compliance testing, as specified in proposed 40
CFR 1071.1(c), the EPA also proposes that manufacturers would be
allowed to divide configurations into NCP subfamilies based on similar
emission characteristics, which could result in different compliance
levels. In some cases, a ``worst-case'' configuration may be necessary
to represent a given NCP family. In proposed new 40 CFR 1071.35(b), the
text states that the EPA's test order would be designed such that the
test sample properly represents the NCP family to ensure that all
engines from the NCP family have emissions at or below the compliance
level. This arrangement is intended to preserve the approach described
in 40 CFR part 86, subpart L.
Section 1071.40: Allowing manufacturers to select a
compliance level that is numerically greater than the value determined
from PCA testing. The compliance level is used to calculate the NCP,
but it also serves as the emission standard for any compliance testing.
As a result, selecting a higher compliance level would result in a
greater NCP but would also give the manufacturer a bigger compliance
margin for managing their compliance risk. In no case would the
compliance level exceed the UL.
Section 1071.40(a): Calculating the compliance level from
PCA testing must account for infrequent regeneration adjustment factors
where appropriate.
Section 1071.40(b): Replacing the table for identifying
the 60th percentile result from PCA testing with an instruction to use
a ceiling function. The ceiling function effectively rounds up to the
next higher integer if there is any non-zero decimal value.\90\ The
ceiling function comes into effect only if manufacturers test more than
24 engines to determine the compliance level.
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\90\ This is analogous to an hourly parking fee that increases
at the start of each successive hour.
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Section 1071.50(a): Changing the deadline for reporting
the results of a production compliance audit from five days to 30 days.
This change aligns with the analogous deadline for reports under
selective enforcement audits under 40 CFR part 1068 and is intended to
allow additional time to ensure that the reported information is
correct and complete.
Section 1071.50(a)(4): Omitting the requirement for the
audit report to identify the method for selecting emission-related
components.
Section 1071.65(a): Clarifying labeling requirements. (1)
The engine's label must meet requirements that apply to all certified
engines, except that the label acknowledges that the engine complies
with current standards using NCPs. (2) Adding NCP labels to engines
that have already been shipped requires manufacturers to either apply
labels or assign the task to an agent. This contrasts with simply
shipping labels to distributors or vehicle owners to apply labels at
their discretion. (3) Adding a requirement for manufacturers to apply
good engineering judgment in selecting the location for supplemental
NCP labels. It is best for all compliance information to be on a single
label, but the EPA is proposing to allow a supplemental label with NCP
information that is near the primary label. The EPA may direct
manufacturers to adjust label location if there is an achievable way to
allow better access to the information.
Section 1071.80(a)(5): Clarifying that MC90 is
graphically represented by the slope of the line segment on the NCP
curve from the published standard up to X.
Section 1071.80(d)(3): The EPA is proposing that the
compliance level be based on engine testing over the FTP duty cycle.
Section 1071.80(d)(4): The EPA is proposing that the
adjusted values for the compliance level for the LLC, idle testing, and
off-cycle testing, as applicable, apply to certification and in-use
testing, as these values serve as the emission standards.
Section 1071.85(b): Adjusting nomenclature to consistently
use i as the counter for calculating NCP values, up to the current or
final value of n years. The current regulation seems to use both i and
n without describing whether they are interchangeable. The proposal
also combines terms as needed to include equations that do not involve
intermediate quantities (such as PR1 and PR2).
Section 1071.85(c): Correcting the usage factor Ai. 40 CFR
86.1113-87(a)(4) states that Ai = 0.08 for i < 2. This would suggest
that there is a usage factor of 0.08 for the first year of allowing
NCPs; however, there can be no annual adjustment in the first year
based on what happened in the previous year. The current regulation
also identifies no value of Ai after the second year of allowing NCPs.
The EPA understands the 0.08 value to apply to i > 2 (for years three
and later).
Section 1071.85(d)(2): Clarifying that the EPA determines
the usage factor fraci-1 based on the extent to which all manufacturers
used NCPs in the previous MY. The result is that all manufacturers use
the same AAF, independent of their own NCP usage.
Section 1071.85(d)(3): Including a website for a
standardized reference to consumer price index for calculating annual
inflation adjustments.
Section 1071.90(c): The EPA is proposing to assess NCPs
based on engines produced during each calendar quarter. This contrasts
with existing 40 CFR 86.1113-87(g), which assesses NCPs based on
engines that have been produced and distributed into commerce. Since
every produced engine will presumably be distributed into commerce in
its production configuration, there is no compelling need to increase
the complexity of counting affected engines by factoring in
[[Page 43194]]
the marketing disposition of individual engines.
Section 1071.90(c)(1): Removing the requirement to include
the date and identification number for the certificate. These items can
be readily identified based on the engine family, which the EPA is
proposing to include in penalty-related reporting.
Section 1071.105(a): Adjusting the reporting requirements
relative to engines found during PCA testing to exceed the Compliance
Level or an emission standard. The EPA is proposing to require
notification within five days after determining that an engine has
failed, and requiring manufacturers to submit a report describing how
they remedied the problem before introducing that engine into U.S.
commerce. In that case, manufacturers could also include the remedy
description in the report describing the results of the audit.
In this rule, the EPA is proposing to migrate the NCP provisions to
a new 40 CFR part 1071. In general, this migration is not intended to
change the compliance program specified in 40 CFR part 86, except as
specifically stated in this proposal. See the EPA's docket memorandum
for a detailed description of the proposed migration.\91\ The EPA
requests comment on proposed provisions that are substantively
different than what applies under 40 CFR part 86, subpart L. (C-26). In
cases where the EPA is not proposing substantive changes to the
regulation, the Agency requests comment on those amendments as
editorial changes.
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\91\ Memorandum to docket EPA-HQ-OAR-2026-0728. ``Detailed
Description of Proposal to Migrate Provisions for Nonconformance
Penalties from 40 CFR part 86, subpart L, to 40 CFR part 1071.''
June 2026.
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V. Improvements for SCR Reliability and Changes to DEF Inducements for
Highway Engines and Vehicles and for Nonroad Diesel Engines
The EPA has heard from farmers, truckers, motor coach operators,
and owners and operators of other diesel equipment who are frustrated
by performance derates that result from problems with emission control
systems in their diesel engines. The result is that these reliance
issues encourage noncompliance with EPA regulations instead of ensuring
the environmental benefits from working emission control technologies.
As described in this section, SCR is a unique emission control
technology because it relies on operators to supply the system with
quality DEF for it to work properly. Consequently, engine manufacturers
have unique requirements to demonstrate that operators properly
maintain the SCR systems compared to other emission control systems.
Throughout this preamble, the term ``inducements'' refers to SCR-
related strategies to induce operators to maintain appropriate levels
of high-quality DEF and not tamper with SCR systems. This section
describes proposed amendments to replace the SCR-related engine
performance derates with visible and/or audible notifications, and
includes corresponding proposed changes to OBD and related
certification requirements to improve SCR reliability. This proposal
generally does not include amendments to derates manufacturers use for
catastrophic engine and aftertreatment protection.
The EPA is aware of these real-world concerns from heavy-duty
vehicle owners and operators due to inducements. For example, during
the development of the 2023 Final Rule, the EPA received comments such
as: ``We have experienced downtime due to lack of power, clogged
filters, DEF issues, and derate issues that put us in a very unsafe
situation with no place or time to pull over safely. Then the cost of
downtime at a dealer, the high cost of towing, and the loss of revenue
and a broker or shipper upset because of all the failures from these
new engines.'' \92\ Operators described how costs go well beyond
financial and can also cost them their reputation or contracts due to
missed or late deliveries. Motorcoach operators described the high
financial cost due to performance restricting inducements, such as when
they need to reimburse passengers for missed events or plane tickets,
as well as the risk it presents when they are providing emergency
evacuation services, such as during hurricanes.\93\ Another commenter
shared that inducements have resulted in people who otherwise would
have remained compliant being motivated to disable emission
controls.\94\
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\92\ Memorandum to Docket EPA-HQ-OAR-2019-0055, regarding
Summary of ANPR Comments Relating to Inducements.
www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0826.
\93\ Memorandum to Docket EPA-HQ-OAR-2019-0055, regarding Letter
to EPA from Bus and Motorcoach Operators Regarding Inducement
Experiences In-Use. www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0779.
\94\ National Automobile Dealers Association Comment on the
EPA's Advance Notice of Proposed Rulemaking. EPA-HQ-OAR-2019-0055-
0369. www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0369.
---------------------------------------------------------------------------
Section V.C of this preamble discusses the proposed changes to
inducement regulations for new MYs 2027 and later highway heavy-duty
engines. Section V.D of this preamble discusses proposed changes
intended to improve the reliability of SCR systems. Section V.E of this
preamble includes a proposal for inducement regulations for new light-
duty and medium-duty vehicles and for new nonroad diesel engines
similar to the proposed requirements for new highway heavy-duty
engines. Finally, section V.F of this preamble discusses the EPA's
consideration of new inducement guidance for in-use diesel engines,
vehicles, and equipment.
A. Background
In 2001, the EPA finalized a rule that promulgated lower
NOX standards for MYs 2007 and later heavy-duty highway
engines.\95\ The EPA adopted those new performance-based standards
based on a projection that manufacturers could use catalyzed
particulate filters and NOX absorber catalysts on diesel-
fueled engines. To reduce NOX emissions, manufacturers
ultimately deployed urea-based SCR systems beginning with MY 2010. SCR
is different from other emission control technologies in that it
requires operators to maintain an adequate supply of DEF to control
emissions.\96\ DEF is stored in a tank located on the vehicle and is
injected into the engine's exhaust upstream of the SCR system.
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\95\ 66 FR 5002 (Jan. 18, 2001). See section I of the preamble
to that rule for more information on the history of emission
regulations for this sector.
\96\ The International Organization for Standardization defines
DEF as a water-based solution with a 32.5 percent urea
concentration. ISO 22241-1:2019 Diesel engines, available here:
https://www.iso.org/standard/66408.html.
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As manufacturers focused on developing SCR technology to meet the
MY 2010 NOX standards, the EPA had three major concerns
related to these systems achieving the intended level of emission
control if operators did not maintain a supply of DEF.
The first concern was that at the time (prior to 2010), there was
no nationwide infrastructure to provide a reliable supply of DEF at
refueling stations. Today, DEF is widely available at retail stores and
filling stations often offer it via pumps in the same lanes as where
diesel-fuel pumps are located.\97\
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\97\ Travel Centers of America. ``Where To Find DEF In Your
Area.'' https://www.ta-petro.com/professional-drivers/def-fuel/.
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The second concern was that operators would leave DEF tanks empty
or would fill DEF tanks with water to reduce operating costs. Filling
DEF tanks is a form of emission-related scheduled maintenance.
Historically, scheduled maintenance was focused on replacing engine
components, such as fuel injectors, to ensure that emission
[[Page 43195]]
controls would work properly throughout an engine's useful life. The
EPA would only allow the use of SCR if manufacturers could demonstrate
that it is reasonably likely that in-use operators would maintain a
consistent supply of DEF. Therefore, to certify engines that use DEF,
manufacturers had to demonstrate to the EPA that operators were
reasonably likely to perform the ``emission-related scheduled
maintenance'' of refilling DEF tanks.\98\ These requirements help
ensure that maintenance occurs so that in-use engines achieve the
intended emission reductions. These requirements also ensure that
engine manufacturers do not demonstrate compliance with the EPA
standards using maintenance practices that are unlikely to occur in the
real world.
---------------------------------------------------------------------------
\98\ The EPA first issued regulations in 1993 (see 40 CFR
86.094-25(b)(6)(ii) as published in 58 FR 4020 (Jan. 12, 1993) to
address how a manufacturer could demonstrate that emission-related
scheduled maintenance was reasonably likely to occur using one of
six methods, including a visible notification, performance
deterioration, surveying in-use vehicles, or doing the maintenance
for free.
---------------------------------------------------------------------------
The third concern was related to operators not using a supply of
quality DEF (i.e., filling the DEF tank with the wrong fluid or
diluting DEF with water). The EPA has treated both DEF supply and DEF
quality as ``adjustable parameters'' based on the possibilities that
operators may keep DEF tanks full, let them run empty, or fill them
with the wrong fluid or diluted DEF. The EPA's existing adjustable
parameter requirements were designed to ensure manufacturers
demonstrate emission standards will be met when an operator could
physically adjust engine components. For example, on older diesel
engines, if a fuel screw was adjustable by an operator using a standard
screwdriver, the manufacturer would need to meet emission standards no
matter how the screw was adjusted (i.e., across the entire
``practically adjustable range''). A manufacturer could instead set the
screw to a particular point and prevent an operator from physically
adjusting the screw (e.g., to prevent an adjustment increasing the
amount of fuel provided to the engine) by using a screw that required a
special tool, permanently gluing the screw in place so it was not
adjustable, or shearing off the head of the screw. Limiting the
adjustment of such a parameter would limit the conditions for which
manufacturers were liable to meet emission standards. Although ensuring
that operators maintained a supply of quality DEF was different than
the historic need for these requirements to prevent mechanical
adjustment, the EPA similarly treated DEF supply and DEF quality as
adjustable parameters.
The EPA issued three guidance documents between 2007-2013 to
describe how manufacturers could demonstrate a reasonable likelihood
that operators would perform the scheduled maintenance of adding DEF to
engines with SCR systems.\99\ The guidance suggested manufacturers
could demonstrate that operators would add DEF by sizing the DEF tank
to correspond with the size of the fuel tank (to allow for adding
diesel fuel and DEF at the same time) and by programming the engine to
derate engine performance and vehicle speed when the DEF tank was
nearly empty. The EPA's guidance suggested that warnings with a visible
notification and a performance derate that ended in a vehicle speed
derate of 5 mph after four hours was a possible primary approach to
notifying and compelling operators to use high-quality DEF. The EPA's
2013 guidance resulted in the widespread use of urea quality sensors
(UQS) to ensure high-quality DEF was used by operators. This proposal
reassesses the continued need for manufacturers to use derates to
demonstrate the reasonable likelihood of operators using quality DEF to
meet emission-related scheduled maintenance requirements.
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\99\ Docket EPA-HQ-OAR-2019-0055-0778. ``Inducement-Related
Guidance Documents, and Workshop Presentation.'' March 15, 2022.
https://www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0778.
---------------------------------------------------------------------------
In addition to derates for DEF supply and DEF quality, the EPA
guidance described a likely need for inducements to prevent operators
from tampering with SCR systems, such as disabling the DEF pump. The
EPA guidance provided a list of components that should likely be
monitored for disconnection (e.g., DEF quality sensors) or blockage
(e.g., to avoid someone crimping a DEF line to prevent flow). The
guidance described applying an inducement of 5 mph after detecting a
tampering condition. This proposal reassesses the continued need for
manufacturers to use derates to demonstrate that operators are not
tampering with SCR systems.
The EPA has also observed that the number of fault conditions
causing inducements has steadily increased far beyond the initial need
to detect problems related to DEF supply, DEF quality, and tampering
with SCR systems. The EPA has learned that malfunctioning components,
such as defective sensors or corroded wiring, can cause performance
derates even though operators are using quality DEF with an adequate
supply. This has contributed to the frustrations expressed by operators
who find themselves unable to operate their vehicles even though they
have properly performed the SCR-related scheduled maintenance and have
not tampered with their engines or emission control systems. The more
stringent 2027 NOX standard will require that engine
manufacturers update their designs with additional components that work
together as part of a larger and more complex system to more carefully
control emissions and continuously monitor performance with additional
sensors and logic for diagnosing emission-related malfunctions. This
greater complexity increases the risk of defects, both for malfunctions
involving increased emissions and for diagnostic malfunctions that show
up as faults even though emissions do not increase.\100\ These
experiences have motivated the EPA to reassess the Agency's approach to
certifying SCR-equipped engines, which require DEF.
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\100\ See section V.C of this preamble for a discussion of
technologies that manufacturers are expected to use to meet the 2027
NOX standard.
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The following sections describe recent EPA actions and policymaking
deliberations related to maintenance, defects, and inducements. The EPA
requests comment on the broader context of operator frustration with
inducements caused by defects rather than operator behavior. (C-27).
Inducements were intended to motivate proper use of DEF in SCR systems
to reduce NOX emissions. DEF has become widely available and
widely used, and late MY trucks and equipment emit far less than older
models. However, in the wake of implementation of inducement schedules,
strong negative public sentiment toward DEF has emerged due to system
failures stemming from sources like failed sensors and the delayed
availability of replacement parts rather than inadequate DEF or an
intent of noncompliance. The EPA has heard from individuals who have
experienced traumatic events, such as lost harvests or stranded
vehicles and products. Observation and word-of-mouth have created
secondary distrust of SCR systems and DEF. The EPA is requesting
comment on the extent to which negative public sentiment about engine
derates has created a distrust associated with SCR system and DEF
failures and how to address the challenge of rebuilding positive
culture around the use of SCR systems and DEF. This might take the form
of educational outreach by manufacturers of engines and manufacturers
of emission-related components. For example, to increase
[[Page 43196]]
public awareness of possible software updates that provide relief from
derate, or to help operators learn how to practice better preventive
maintenance to reduce downtime. This might also take the form of
additional engineering to focus on product improvements for which
defects are most common.
B. Recent Developments
1. Changes to Inducements Made in the 2023 Final Rule
The 2023 Final Rule formalized an updated approach for
demonstrating that operators would maintain a consistent supply of
quality DEF for SCR-equipped in-use engines used in heavy-duty highway
engines and vehicles. Specifically, the EPA codified requirements that
describe how manufacturers can design engines with a derate schedule to
demonstrate that operators would be reasonably likely to maintain a
supply of quality DEF.\101\
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\101\ See the inducement requirements specified in 40 CFR
1036.111.
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The 2023 Final Rule also specifies that DEF supply and DEF quality
are adjustable parameters.\102\ Regarding DEF supply, the EPA finalized
that the physically adjustable range includes any amount of DEF for
which the engine's control system does not trigger an inducement. For
DEF supply, the EPA also finalized that the inducement schedule starts
with visible notifications three hours prior to the tank being empty.
---------------------------------------------------------------------------
\102\ See 40 CFR 1036.115(f).
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The EPA did not finalize proposed revised requirements for
determining the physically adjustable range of DEF quality in the 2023
Final Rule. This is discussed in more detail in section V.D.1 of this
preamble.
The 2023 Final Rule made several changes to reduce the severity of
inducements, as compared to the EPA's prior SCR-related guidance.
Importantly, the regulation does not specify a derate to 5 mph within
four hours after detecting a fault condition. The regulation instead
specified an immediate initial restriction in allowable speed and
further decreases in allowable speed until a final inducement speed of
25 mph is reached. The time prior to final inducement depends on the
average speed of the vehicle's actual operation, varying from 30 hours
to 164 hours.
The EPA also added requirements to ensure the engine's control
system will validate when an inducement condition no longer exists and
remove the inducement. For example, if an operator flushed and refilled
a DEF tank to replace poor quality DEF, the system will recognize this
action and remove the inducement. The 2023 Final Rule also required
generic scan tools to report SCR- and DPF-related derate fault code
information and to be capable of removing a final inducement condition.
Expanding the capability of generic scan tools helps users avoid costly
towing bills and trips to repair facilities after taking action to
address problems. These provisions continue to be important during the
proposed transition from performance derates to visible and/or audible
notifications.
2. The EPA's August 2025 Inducement Guidance
In the 2023 Final Rule, the EPA indicated a willingness to allow
manufacturers to modify in-use heavy-duty highway engines and vehicles
with software updates that incorporate some or all of the inducement
provisions in the 2023 Final Rule. To encourage manufacturers to make
updates to in-use engines and vehicles, in August 2025 the EPA issued
revised inducement guidance for existing vehicles up to and including
MY 2026 to allow more time before a final inducement of 25
mph.103 104 This guidance applied not only to highway heavy-
duty engines, but also to in-use highway light-duty and medium-duty
vehicles and nonroad diesel engines.
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\103\ U.S. Environmental Protection Agency. (2025). ``At Iowa
State Fair, EPA Administrator Zeldin Announces Diesel Exhaust Fluid
(DEF) Fix.'' www.epa.gov/newsreleases/iowa-state-fair-epa-administrator-zeldin-announces-diesel-exhaust-fluid-def-fix.
\104\ U.S. Environmental Protection Agency. (2025). IACD-2025-
10, ``Revised Guidance for Light Duty Vehicles, Heavy-Duty Diesel
Engines and Nonroad Compression-Ignition (CI) Engines Using
Selective Catalyst Reduction (SCR) Technologies.'' www.epa.gov/system/files/documents/2025-08/def-ltr-manufacturer-2025-0811.pdf.
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3. EPA Requests for Manufacturer SCR-Related Warranty Data
Under CAA section 208(a), the EPA is authorized to require
manufacturers to provide information needed to assess whether emission
control systems are functioning properly and whether manufacturers are
meeting their obligations to identify and fix defects. On February 3,
2026, the EPA requested information from the top 14 highway and nonroad
diesel engine manufacturers that account for over 80 percent of all
products using SCR systems. Specifically, the EPA requested data on
warranty claims, failure rates, and repair information for MYs 2016,
2019, and 2023 emission control products to determine whether ongoing
DEF system failures are related to a specific generation of products or
specific SCR-system components.\105\ The EPA has received this data and
is evaluating it to independently evaluate ongoing system failures, and
the Agency may take further action based on what the Agency learns from
this data.
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\105\ U.S. Environmental Protection Agency. (2026).
``Administrator Zeldin Takes Additional Measures to Address Diesel
Exhaust Fluid (DEF) Issues for American Farmers and Truckers.''
https://www.epa.gov/newsreleases/administrator-zeldin-takes-additional-measures-address-diesel-exhaust-fluid-def-issues.
---------------------------------------------------------------------------
4. The EPA's March 2026 DEF Quality Monitoring Guidance
In 2013 for SCR-equipped highway diesel engines and in 2014 for
SCR-equipped nonroad diesel engines, the EPA issued guidance describing
the adjustable parameter provisions of the Agency's regulations, and
the Agency's conclusion that UQS) could be installed in new highway
vehicles by MY 2016 and in new nonroad equipment by MY 2017 to meet the
Agency's adjustable parameter regulations.106 107 The EPA
also acknowledged that NOX sensors had been successfully
used to meet these requirements in previous MYs, and NOX
sensors could continue to be used to meet requirements related to DEF
quality. Since that time, only one diesel engine manufacturer has
continued to demonstrate compliance using NOX sensors to
determine urea concentration. All other manufacturers switched to UQS
because of the UQS's ability to directly measure DEF quality and more
quickly determine if DEF has been diluted. Together with the
manufacturers, the EPA has recently identified UQS as having among the
highest failure rates of any SCR components and that using alternative
detection methods (e.g., NOX sensors) could further improve
SCR system robustness and reduce unnecessary inducements. The EPA's
preliminary assessment of warranty data submitted to the Agency in
response to the February 2026 information requests further suggests
that UQS failures are a significant source of warranty claims and DEF-
related inducement. Given this, the EPA issued revised guidance in
March 2026 to make clear that alternative methods of meeting the
adjustable parameter provisions, including the use of NOX
sensors, are allowed under EPA regulations. The
[[Page 43197]]
EPA also stated that software updates using certain alternative
detection methods may be made to existing diesel engine products in
place of, or to augment, existing UQS-based systems without such action
being considered tampering under the CAA.\108\
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\106\ U.S. Environmental Protection Agency. (2013). CISD-13-13,
``Testing of Heavy-Duty Diesel On-Highway Engines with Adjusted
Diesel Exhaust Fluid (DEF) Quality.'' https://dis.epa.gov/otaqpub/display_file.jsp?docid=31221&flag=1.
\107\ U.S. Environmental Protection Agency. (2014). CISD-14-10,
``Certification of Nonroad Diesel Engines Equipped with SCR Emission
Controls.'' https://dis.epa.gov/otaqpub/display_file.jsp?docid=32298&flag=1.
\108\ U.S. Environmental Protection Agency. (2026). ``DEF
Quality Monitoring Using Alternate Sensor Technologies,'' Guidance
Document: IACD-2026-05 (LDV, HDE, NRCI). www.epa.gov/system/files/documents/2026-03/iacd-2026-05-def-guidance-ltr-2026-0326.pdf.
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C. The EPA's Proposed Inducement Revisions
This section discusses the EPA's reasons for reconsidering existing
inducement regulations for MYs 2027 and later highway heavy-duty
engines and vehicles, and proposed changes to the Agency's existing
inducement requirements.
1. The EPA's Reassessment of Inducements
The EPA Administrator has said ``[a]s I traveled to all 50 states
during my first year as EPA Administrator, I heard from truck drivers,
farmers, and many others rightly complaining about DEF and pleading for
a fix.'' \109\ In response to feedback and concerns that the EPA
continues to receive regarding the impact of inducements that affect
the performance of heavy-duty engines and vehicles, the Agency is
reassessing whether derates are necessary for SCR compliance. This
section presents key reasons the EPA is reassessing the need for
derates for SCR compliance.
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\109\ U.S. Environmental Protection Agency. (2026).
``Administrator Zeldin Takes Additional Measures to Address Diesel
Exhaust Fluid (DEF) Issues for American Farmers and Truckers,''
www.epa.gov/newsreleases/administrator-zeldin-takes-additional-measures-address-diesel-exhaust-fluid-def-issues.
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The 2023 Final Rule presented a series of principles the EPA
considered when evaluating how to address concerns related to
maintaining the operation of emission control systems.\110\ The EPA's
2023 Final Rule also raised questions about how restrictive derates
should be to provide a reasonable basis for demonstrating that
operators would continue to add quality DEF in tanks and not tamper
with SCR systems. However, the 2023 Final Rule did not include any
reference to relying on visible and audible notifications instead of
derates as the sole means of prompting operators to perform
maintenance.
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\110\ 88 FR 4377 (Jan. 24, 2023).
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The reassessment in this proposed rule revisits questions and
principles discussed in the 2023 Final Rule, including how to apply
these principles to find the least restrictive means of accomplishing
the goal of ensuring operators add quality DEF in tanks and prevent
tampering with SCR systems. The three principles considered in the 2023
Final Rule that are of particular relevance are: (1) ensuring critical
emission-related scheduled maintenance has a reasonable likelihood of
being performed while also deterring tampering of the SCR system, (2)
addressing operator concerns with false inducements and low inducement
speed restrictions that occur quickly, and (3) reducing the likelihood
of in-use tampering by reducing operator frustration with derates.
While vehicle owners and operators have not yet experienced the
inducement requirements finalized in the 2023 Final Rule, the EPA has
heard from enough owners and operators of diesel engines frustrated
with SCR inducement derates that the Agency has decided to reassess the
need to continue to rely on derates for diesel engines using SCR.\111\
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\111\ U.S. Environmental Protection Agency. (2026).
``Administrator Zeldin Takes Additional Measures to Address Diesel
Exhaust Fluid (DEF) Issues for American Farmers and Truckers.''
www.epa.gov/newsreleases/administrator-zeldin-takes-additional-measures-address-diesel-exhaust-fluid-def-issues.
---------------------------------------------------------------------------
Comments received in response to the proposal of the 2023 Final
Rule were also reviewed as part of this reassessment of inducements.
Commenters expressed frustration with the process of relying on the
engine's electronic controls to make a judgment on tampering without
being able to consider problems caused by component failure.\112\
Commenters stated that engines are designed with algorithms that
calculate a probability that tampering has occurred, without being able
to confirm it has occurred.\113\ Commenters shared their experiences
with derates for system defects unrelated to tampering, with no
opportunity for operators to appeal to demonstrate that no tampering
occurred prior to or even after a derate had been initiated by the
engine's control system.\114\ Commenters stated that, in some cases,
components were identified as defective by the diagnostic system but
were not actually faulty, which means that derate occurred despite
emission controls working properly.\115\ Furthermore, one manufacturer
commented that it was difficult to differentiate between tampering or
urea crystallization that can cause plugged lines that prevent DEF
flow.\116\
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\112\ See, e.g., American Trucking Associations comment on the
EPA's Advance Notice of Proposed Rulemaking. EPA-HQ-OAR-2019-0055-
0357. www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0357.
\113\ See, e.g., National Association of Small Trucking
Companies comment on the EPA's Advance Notice of Proposed
Rulemaking. EPA-HQ-OAR-2019-0055-0456. www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0456.
\114\ See, e.g., Indiana Motor Truck Associations comment on the
EPA's Notice of Proposed Rulemaking. EPA-HQ-OAR-2019-0055-0357.
www.regulations.gov/document/EPA-HQ-OAR-2019-0055-1095.
\115\ Memorandum to Docket EPA-HQ-OAR-2019-0055, ``Summary of
ANPR Comments Relating to Inducements.'' www.regulations.gov/document/EPA-HQ-OAR-2019-0055-0826.
\116\ Cummins comment on the EPA's Notice of Proposed
Rulemaking. EPA-HQ-OAR-2019-0055-1325. https://www.regulations.gov/comment/EPA-HQ-OAR-2019-0055-1325.
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In response to these concerns, the EPA narrowed the list of
tampering triggers in the 2023 Final Rule. Inducements depend on the
engine's diagnostic systems being able to accurately distinguish
between problems directly caused by an operator tampering or not
supplying quality DEF and problems caused by defective components. The
EPA attempted to refocus inducement triggers in the 2023 Final Rule,
for example by limiting the tampering-related triggers to ``open
circuit'' faults that would occur if an operator unplugged a component
(e.g., a DEF pump). However, there remains risk that the judgments made
by the engine's diagnostic system on the remaining inducement triggers
may not always accurately distinguish between tampering and defective
components but nevertheless uses derates for both. This concern for
recognizing the limits of algorithm-based judgments is an important
factor to consider in reassessing the role of derates to ensure that
operators are maintaining the DEF supply and not tampering.
The February 2026 SCR-related warranty claim data, which the EPA
required highway and nonroad diesel engine manufacturers to provide,
can help identify certain areas in which improvements to components or
software calibrations might be made to improve SCR system reliability
(see section B.3. for further discussion on the Agency's request). It
is important to note that most of this data is likely to provide
insight into failures within the manufacturer's warranty period (e.g.,
generally under 200,000 miles and two years for heavy-duty highway
engines and vehicles) versus over the entire useful life. In general,
heavy-duty highway diesel SCR systems were first introduced in MY 2010,
and nonroad diesel SCR systems were first introduced in MY 2014.
Therefore, much of the in-use fleet of SCR-equipped engines, vehicles,
and equipment are now outside of the manufacturer's warranty period.
The SCR failures that are frustrating owners
[[Page 43198]]
and operators may reflect design defects that could be revealed in the
warranty data, but also likely reflect harsh real-world conditions in
which diesel engines operate for hundreds of thousands of miles. For
example, wiring harness degradation due to age or corrosion in
connectors after hundreds of thousands of miles can provide inaccurate
readings that, as discussed above, can be interpreted by the engine's
diagnostic system as a tampering event and result in an engine
derate.\117\
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\117\ See Memorandum to docket EPA-HQ-OAR-2019-0055-0967. ``TSB
Aftertreatment Faults.'' Sept. 9, 2021.
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One factor the EPA considered in the 2007 to 2010 timeframe, when
manufacturers informed the Agency of their plans to introduce SCR
technology for heavy-duty highway applications beginning in MY 2010,
was the availability of DEF. At that time, DEF was not available at
most diesel refueling stations or other retail outlets. That reality
informed the EPA's early guidance documents regarding the use of DEF
and inducements. As discussed in section V.A of this preamble, DEF
availability is no longer a constraint to the operational feasibility
of SCR technology in heavy-duty highway applications. DEF is widely
available nationwide, including at fuel stations with dedicated
dispensing pumps, meaning DEF can be refilled at the same time diesel
is being pumped. Diesel vehicle owners and operators are now familiar
with DEF and have over a decade of experience using it across the
country.
Today, many engine manufacturers utilize compensation algorithms
that adjust the amount of DEF injected to account for DEF that is not
at the nominal 32.5 percent urea concentration, such that adding water
to dilute DEF would only cause the engine to increase the amount of DEF
injected to achieve the manufacturer's intended quantity of urea for
controlling emissions. The EPA believes this discourages the potential
for operators to purposefully dilute DEF as a potential means to reduce
operating costs. The increased DEF consumption due to the compensation
algorithms increases the risk that DEF tanks would be empty prior to
the next refueling event, which would require operators to spend more
time stopping to refill DEF. This could take away the convenience of
refilling DEF at the pump with fuel refills. Adding water could also
void an aftertreatment warranty claim and, even after the warranty
period has expired, many operators would also not want to risk damaging
the SCR system by intentionally using the wrong fluid.
As a part of this reconsideration of inducements that reduce engine
and vehicle performance, the EPA has considered other examples of
vehicle operations that encourage an operator to take specific action.
In particular, the EPA reviewed two recent studies on the success of
visible and audible notifications used to prompt light-duty vehicle
drivers to wear seatbelts.118 119 There are clearly
differences in the use of seatbelts and the use of DEF. For example,
the financial impact is different; the use of DEF increases the
operating cost of a diesel-fueled vehicle while the use of a seatbelt
is free. The risks are also different; not wearing a seatbelt can have
severe repercussions for the operator, including serious injury or
death, while currently not using DEF can result in a vehicle speed
derate. The underlying principle of designing a system to motivate
seatbelt usage is very relevant for the EPA when considering
inducements. As NHTSA stated in a final rule in 2025, ``[a]n optimized
warning system balances effectiveness and annoyance, so that the
warning is noticeable enough that the occupants will be motivated to
fasten their belts, but not so intrusive that an occupant may attempt
to circumvent or disable it or the public will not accept it.'' \120\
The seatbelt studies noted previously stated that frequent audible
warnings that last for 90 seconds or longer can significantly increase
seatbelt use compliance. One of these studies also found that seatbelt
speed-limiting interlocks (e.g., a 15-mph speed limit enacted when
seatbelts were not fastened) were not more effective than frequent,
long audible warnings; participants circumvented the speed-limiting
interlock to drive unbelted more than with audible reminders.
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\118\ Kidd, D. G., and Singer, J. (2019). The effects of
persistent audible seat belt reminders and a speed-limiting
interlock on the seat belt use of drivers who do not always use a
seat belt. Journal of Safety Research. www.iihs.org/research-areas/bibliography/ref/2185.
\119\ Kidd, D. G., and O'Malley, S. (2023). Increasing seat belt
use in the United States by promoting and requiring more effective
seat belt reminder systems. Traffic Injury Prevention, 24(sup1),
S80-S87. https://doi.org/10.1080/15389588.2022.2134730.
\120\ 90 FR 396 (Jan. 3, 2025).
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2. Proposed Inducement Requirements
The EPA is proposing to replace engine performance derates for SCR-
related inducements with the alternative approach of having the
engine's control system alert operators with visible and/or audible
notifications of the need to address concerns with the emission control
systems, such as to replenish DEF supply or warn of possible tampering.
The proposed audible notification would be in addition to visible
notifications already being used. The EPA expects these proposed
revisions to the Agency's SCR inducement requirements for heavy-duty
diesel engines would require software-based changes, which are
considered indirect costs associated with research and development. See
section 3.1.2 of the DRIA for this proposed rule for a discussion on
indirect costs. The EPA requests comment on any costs or savings
associated with these changes relative to the 2023 Final Rule (i.e.,
software development costs or savings associated with removing the 2023
Final Rule requirement to determine a vehicle's average speed and then
assign a specific derate schedule based on that speed). (C-28).
Visible notifications for certain SCR-related maintenance issues
were included in the EPA's early guidance on the use of DEF and are
also used by the OBD system, which displays the MIL (i.e., the ``check
engine light'') to flag system faults. The 2023 Final Rule included
requirements to display additional information on SCR system and DPF
problems (e.g., erratic temperature sensor readings that prevent DPF
regenerations from occurring which can result in a plugged DPF) that
result in a derate. The regulations at 40 CFR 1036.110(c) currently
specify basic elements of visible notifications and require EPA
approval for detailed specifications. The EPA will work with industry
to adopt standardized specifications for SCR-related notifications if
additional changes are needed.
The EPA is proposing a separate audible notification schedule for
DEF level because, as discussed in section V.A of this preamble,
industry has proven that refilling DEF is easy and DEF is readily
available at retail stores and diesel refueling stations nationwide.
Therefore, it should not require much time to find and refill DEF to
resolve the audible notification.
The EPA is proposing that a 90-second audible notification would be
required at the frequency shown in Table V-1 below. The EPA is
proposing a 90-second audible notification because studies have shown
that a 90-second notification is effective in increasing seatbelt usage
in passenger cars.\121\
[[Page 43199]]
There are important differences between passenger vehicle operators and
heavy-duty truck operators that the EPA considered when developing the
proposed schedule. For example, truck drivers have additional
professional licensing and training requirements. As commercial vehicle
operators, they are accustomed to paying close attention to warning
lights in general because they rely on the vehicle operating as
intended to support a business and one check engine light can indicate
multiple problems. Additionally, line-haul trucks operate in a manner
that routinely takes them far away from their home location, in many
cases thousands of miles away, and freight movement generally pays by
the mile. Other commercial operators, such as refrigerated food and
beverage trucks or refuse trucks, may be particularly motivated to
avoid breakdowns to remain on schedule.
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\121\ Kidd, D. G., and O'Malley, S. (2023). Increasing seat belt
use in the United States by promoting and requiring more effective
seat belt reminder systems. Traffic Injury Prevention, 24(sup1),
S80-S87. https://doi.org/10.1080/15389588.2022.2134730.
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The EPA also considered both how long operators are in their
vehicles and how far apart refueling stations are when developing the
proposed audible notification schedule. Operators of heavy-duty
vehicles are bound by Hours-of-Service requirements published by the
Department of Transportation.\122\ The basic requirement is that
drivers must take a 30-minute break when they have driven for a
cumulative 8-hour period. It is not uncommon for drivers to spend 2-4
hours on the road between breaks. In addition, it is reasonable to
estimate that the average distance between most refueling stations is
50 miles, or approximately one hour, although this depends on where a
truck is operating.\123\ For example, in or close to a city there are
stations and retail stores that sell DEF within minutes of each other.
On the other hand, there are remote areas where there may be a few
hours between stops. The general expectation is that (1) drivers will
refill DEF tanks when they refill diesel fuel and, with the 1:1 ratio
of DEF to diesel fuel, running out of DEF should not occur between fuel
stops, and (2) fuel stops are available on average one hour apart.
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\122\ Hours of Service information can be found here: https://www.fmcsa.dot.gov/regulations/hours-of-service.
\123\ See https://www.mmcginvest.com/post/the-u-s-truck-stop-economy-an-ultimate-guide-to-full-service-travel-plazas.
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For this reason, the EPA is proposing a different frequency for DEF
level audible notification. This audible notification schedule attempts
to balance effectiveness and annoyance by making it frequent enough to
motivate an operator to refill DEF, but allowing adequate time between
notifications to stop and refill to avoid a notification that is so
intrusive that they may attempt to circumvent or disable, resulting in
prolonged NOX emissions above the standards.
The EPA is proposing to retain the provision in 40 CFR
1036.111(b)(1) that the first inducement notification will start three
hours prior to the tank becoming empty or when the tank is at 2.5
percent full. This three-hour warning for low DEF is something
operators are used to and should provide more than sufficient time for
stopping to refill DEF during a scheduled break in a manner that would
avoid interrupting their trip. The EPA is requesting comment on whether
this provision should be retained, modified, or not included in the
revised inducement requirements. (C-29).
The EPA is proposing to retain the tampering inducement triggers
described in 40 CFR 1036.111(b)(4) and to set a schedule for DEF
quality and tampering signals that is slightly different than the
schedule for DEF level. This is because it is expected that, due to the
improvements the EPA made in the 2023 Final Rule to reduce the number
and type of tampering triggers and to reduce the number of false
inducements, these inducements would occur only if there was a problem
not easily solvable by adding DEF. As discussed in section V.C.1 of
this preamble, the EPA is concerned that these types of failures mostly
occur because the engine's diagnostic system has difficulty detecting
the difference between tampering and faulty components. These issues
can be more difficult to resolve and may require specialized repair
facilities and tools. As the EPA discussed in the proposal to the 2023
Final Rule, commenters noted that it can take three days to schedule an
appointment with a repair facility. Therefore, for DEF quality- and
tampering-related failures, the EPA is proposing a less frequent
audible notification schedule than the proposed audible notification
schedule for DEF level. The EPA is proposing that for DEF level, the
first audible notification occurs three hours prior to the tank
becoming empty, at the time the tank is empty, 30 and 60 minutes after
becoming empty, with a final frequency of every hour until the
condition is resolved. The EPA is proposing that for DEF quality and
tampering, the first audible notification occurs at the time the
condition is detected, 30 and 90 minutes after detection, with a final
frequency of every three hours until the condition is resolved.
[GRAPHIC] [TIFF OMITTED] TP14JY26.014
The EPA is requesting comment on several aspects of the proposed
requirements for audible notifications as shown in Table V-1. (C-30).
The EPA requests comment on advantages and disadvantages to creating a
separate audible notification schedule for DEF level. The EPA requests
comment on the audible notification length, including whether it should
last for more or less than 90 seconds each time. The EPA is requesting
comment on the frequency of the notifications, including whether more
or less frequent notifications would be appropriate for demonstrating
[[Page 43200]]
that operators are reasonably likely to take appropriate action,
including but not limited to whether the notification should be only at
key-on or if there should be a certain number of notifications during a
single trip. The EPA requests comment on whether audible notifications
are helpful in addition to visible notifications, as a prompt for
operators to refill DEF or take other action to maintain SCR systems.
The EPA requests comment on whether visible notifications should be
continuously illuminated, or whether a flashing indicator would be more
effective. The EPA requests comment on whether visible and/or audible
notifications are inadequate for providing a reasonable assurance that
operators will provide a supply of quality DEF in tanks and not tamper
with SCR systems. The EPA requests comment on whether the regulation
should preserve a more modest schedule of performance derates than
specified in the 2023 Final Rule to prompt operators to take action or
derates similar to the schedules the Agency included in the August 2025
guidance. For example, the regulation could keep the derate schedule as
adopted in 40 CFR 1036.111 for low-speed, medium-speed, and high-speed
vehicles, but apply only one or two derate steps after detecting an
inducement triggering condition to include more or different criteria
in the list of inducement triggering conditions. Finally, the EPA
requests comment on whether changes to notifications and derates should
lead the Agency to include more or different criteria in the list of
inducement triggering conditions.
The proposed approach includes several amendments to the
regulations that were adopted in the 2023 Final Rule. First, the EPA is
proposing to remove 40 CFR 1036.111(a)(2), which specifies how a
manufacturer must determine to what speed-category a vehicle belongs.
Second, the EPA is proposing to remove 40 CFR 1036.111(a)(3), which
specifies the rate at which a vehicle speed derate is implemented.
Third, the EPA is proposing to remove 40 CFR 1036.111(d), which
includes the derate schedule for vehicles.
Fourth, the EPA is proposing to modify 40 CFR 1036.110(c)
requirements to remove all requirements related to displaying the
inducement derate schedule.
Fifth, the EPA is proposing to amend 40 CFR 1036.111(e) to replace
references to ``derates'' with ``visible and/or audible
notifications,'' and to remove paragraph (e)(3) that requires
restarting derates at the same point in the derate schedule for
inducement triggering conditions that recur after less than 40 hours of
engine operation. If the EPA retained paragraph (e)(3) for the audible
notification schedule in Table V-1, a recurring inducement condition
could trigger an audible notification at the final frequencies of one
notification every 1-3 hours. By removing the recurring fault
requirement, the proposed audible notifications would occur at the more
frequent initial levels. The EPA is requesting comment on whether this
provision should instead be retained or modified. (C-31).
Sixth, the EPA is proposing to modify 40 CFR 1036.125(h)(8) to
adjust the requirements related to information in the owner's manual
describing the inducement derate schedule to reflect the proposed
visible and/or audible notifications.
Seventh, the EPA acknowledges that manufacturers may choose to
continue to apply derates to protect the engine or aftertreatment
system from catastrophic damage, for example if low coolant is causing
the engine to overheat, or if a lack of DEF could cause a DEF injector
to overheat and fail.\124\ The EPA is therefore proposing to clarify
that manufacturers may continue to use engine derates to protect the
engine or aftertreatment systems from catastrophic damage. The EPA is
requesting comment on whether this proposal should be more or less
restrictive. (C-32).
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\124\ Gribbins, K. (2020). ``Beat the Heat: Daily Maintenance
for Off-Highway Engines Dealing with Hot Weather and Work.'' https://compactequip.com/engines/beat-the-heat-daily-maintenance-for-off-highway-diesel-engines-dealing-with-hot-weather-and-work.
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The EPA is proposing to require manufacturers to design their
engines with visible and/or audible notifications to prompt operators
to supply quality DEF in tanks instead of derating, as described in
this proposal, no later than MY 2029. Under the proposal, manufacturers
may also make this transition for new engines any time before MY 2029.
The EPA recognizes that manufacturers have been working toward
designing their heavy-duty diesel engines and vehicles with inducement
requirements as adopted in the 2023 Final Rule. This proposal retains
the general requirements specified in 40 CFR 1036.110 and 1036.111 for
MYs 2027 and 2028. The EPA requests comment on the potential need to
provide additional lead-time for implementing the proposed inducement
changes, specifically if the Agency should, instead, require this
change by MY 2030 or MY 2031. At the same time, the EPA is interested
in accelerating the change to the long-term approach described in this
proposal. Toward that end, the EPA requests comment on adjustments or
simplifications to the inducement provisions adopted in the 2023 Final
Rule that engine and vehicle manufacturers could apply before MY 2029,
considering the need for sufficient time to implement such changes. (C-
33).
D. Proposed Revisions To Improve SCR Reliability
This section also includes proposals to modify existing OBD
requirements aimed at improving the reliability of heavy-duty highway
diesel engines and vehicles with SCR systems.
1. DEF Quality Detection Proposal
It has been over a decade since the EPA has evaluated how best to
consider adjustable parameters requirements as they apply to DEF
quality, which can vary due to production or storage issues,
degradation with age or environmental conditions, or dilution with
water. In this section, the EPA proposes several amendments to improve
how manufacturers can comply with emission standards by ensuring that
operators are reasonably likely to use proper quality DEF. The purpose
of these proposed changes is to design a program that will monitor for
meaningful DEF quality issues and not create operator frustration with
overly precise monitoring.
As described in sections V.A and V.C.1 of this preamble, there was
concern when SCR was first introduced into the market over a decade ago
that DEF availability may be limited and some operators may use water
instead of DEF. Today, quality DEF is widely available and operators
have an established practice of purchasing DEF along with diesel fuel.
While information on nationwide in-use tampering rates is difficult to
find, the EPA expects there is very little intentional diluting of
DEF.\125\ In the unlikely event that an operator fills the DEF tank
with water or mistakenly adds diesel fuel to the DEF tank, the engine's
control system prompts operators to take action. As discussed in
section V.C.1 of this preamble, users are generally aware that such
actions can damage equipment and void warranty claims, and the EPA
expects they would quickly address the problem by flushing the system
and replacing DEF. Also,
[[Page 43201]]
manufacturers have developed DEF dosing compensation algorithms that
can increase or decrease the amount of DEF being dosed to address DEF
variability. These compensation features cause DEF dilution to be a
self-defeating strategy, as any dilution generally results in more
volume of DEF being consumed and more time spent stopping to refill DEF
tanks. DEF dilution has therefore become an unlikely scenario that does
not cause the same weight of concern it once did. However, the EPA
recognizes that in-use DEF might have varying concentration for reasons
other than tampering, such as production variability or DEF degradation
due to long-term storage, sun exposure, or storage temperature, which
can occur after a DEF tank was filled with DEF with the nominal 32.5
percent urea concentration.\126\ Manufacturers' compensation algorithms
are designed to address DEF variability caused by production
variability or storage conditions by increasing or decreasing the
amount of DEF being dosed.
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\125\ U.S. Environmental Protection Agency. (2021). ``Tampered
Diesel Pickup Trucks: A Review of Aggregated Evidence from EPA Civil
Enforcement Investigations.'' https://www.epa.gov/enforcement/tampered-diesel-pickup-trucks-review-aggregated-evidence-epa-civil-enforcement.
\126\ DEF exposed to temperatures above 86 [deg]F can degrade,
decreasing urea concentration. DEF stored in conditions below
freezing can develop ice that dilutes the urea concentration.
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In preparation for submitting comments on the 2023 Final Rule, CARB
performed a limited survey of 33 randomly selected California fleets to
better understand their experience with inducements.\127\ CARB
commented that ``In the survey, fleets that experienced derates were
asked for the cause, and 37 percent were for failed NOX
sensors or DEF quality sensors. This was by far the most common cause
of derate conditions.'' The comment noted that no fleets reported
derates due to bad DEF quality (e.g., urea concentration outside of a
manufacturer's specification or diluted with water), which CARB
suggested was consistent with industry efforts to assure the high-
quality DEF supply chain and CARB staff's earlier surveys of DEF
availability and driver usage.
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\127\ California Air Resources Board comments on the EPA's
proposed rule. EPA-HQ-OAR-2019-0055-1186. https://www.regulations.gov/document/EPA-HQ-OAR-2019-0055-1186.
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In the 2023 Final Rule, the EPA promulgated 40 CFR 1036.115(f)(3),
which maintains that DEF supply and DEF quality are adjustable
parameters, and specifies that the practically adjustable range
includes any amount of DEF supply for which the engine's control system
does not trigger an inducement under 40 CFR 1036.111. The EPA proposed,
but did not finalize, in the 2023 Final Rule to further specify in
regulatory text that the physically adjustable range would also include
any quality of DEF for which the engine's diagnostic system does not
trigger inducement. Instead, as stated in the 2023 Final Rule, for
compliance with 40 CFR 1036.115(f)(3) with regard to DEF quality,
manufacturers could continue to rely on the existing guidance in CISD-
13-13 describing how manufacturers can demonstrate compliance with
emission standards over the practically adjustable range for DEF
quality.\128\ In the 2023 Final Rule, the EPA intended to further
consider the relationship between inducements and the practically
adjustable range for DEF quality in the future.
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\128\ U.S. Environmental Protection Agency. (2014). CISD-14-10,
``Certification of Nonroad Diesel Engines Equipped with SCR Emission
Controls.'' https://dis.epa.gov/otaqpub/display_file.jsp?docid=32298&flag=1.
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In the EPA's guidance document CD-13-13, the Agency explained that
DEF quality would generally be considered an adjustable parameter, and
that ``poor quality DEF'' is any urea concentration at which the engine
is unable to meet emission standards. This point can vary from
manufacturer to manufacturer and from engine to engine. The guidance
explained that the EPA considered the practically adjustable range for
emission testing to be from nominal DEF with a 32.5 percent urea
concentration down to the point at which the engine is unable to meet
emission standards (the first point at which a manufacturer must start
an inducement). This means that manufacturers must be able to precisely
detect urea concentrations different than the nominal 32.5 percent,
demonstrate that they can meet emission standards by compensating, or
trigger an inducement for a DEF quality concern.
In the 2023 Final Rule, some commenters raised concerns that the
numerically lower NOX standards for MY 2027 will cause the
corresponding range of adjustment to be narrower. For example, the
Truck and Engine Manufacturers Association (EMA) commented on the 2023
Final Rule, noting ``. . . manufacturers have too little experience
with the complex future emissions control systems required to meet the
proposed very stringent standards to know if compliance can be assured
at the urea concentration limits detectable by [DEF Quality Sensor]
systems.'' EMA added that they were concerned that the EPA did not
perform testing to demonstrate the impacts of DEF quality with lower
NOX standards.\129\ The EPA acknowledges that manufacturers
using the guidance in CD-13-13 to certify to MYs 2027 and later
NOX standards would have a smaller margin to tolerate
fluctuations in DEF outside of the nominal specification due to
variations in urea concentration.
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\129\ Truck and Engine Manufacturers comments on the EPA's
proposed rule. EPA-HQ-OAR-2019-0055-1203., p. 125. https://www.regulations.gov/document/EPA-HQ-OAR-2019-0055-1203.
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While the EPA is proposing to remove inducements as noted in
section V.C of this preamble, the Agency also wants to ensure the
detection systems are not overly precise such that visible and/or
audible notifications are improperly triggered for conditions outside
of the operator's control. For example, the EPA has learned that DEF
quality sensors can trigger false urea concentration faults after a
simple DEF refill that creates bubbles in the fluid.\130\
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\130\ See https://www.fama.org/wp-content/uploads/2021/12/TC081-FAMA-DEF-Sensor-Guidance-211227-2.pdf.
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The EPA is proposing the following amendments to maintain the
integrity of DEF quality notifications by ensuring they are only
triggered for meaningful DEF quality problems. First, the EPA is
proposing to amend 40 CFR 1036.115(i) by adding a requirement for
manufacturers to design their engines to include compensation
algorithms that adjust DEF flow to maintain emission control by
compensating for DEF with a reduced urea concentration. This is
intended to reflect current practice. Compensation algorithms would
need to adjust DEF flow to maintain a level of emission control that is
comparable to operation with DEF at the nominal 32.5 percent urea
concentration. Compensation would be required up to the hardware
limits. For example, given the design of a DEF injector, it will have a
maximum amount of DEF flow that limits the amount of compensation that
is possible. As a point of reference, the EPA has adopted a similar
approach of requiring compensation for nonroad spark-ignition engines
using noncommercial fuels, such as those that operate on field gas from
landfills or oil wells.\131\ The EPA is also proposing to amend 40 CFR
1036.205(b)(12) to require manufacturers to describe their design for
compensation algorithms related to DEF quality in the application for
certification. The EPA is requesting comment on the feasibility of DEF
dosing continuing after a DEF quality notification is enacted (e.g., if
the urea concentration is less than 20 percent). (C-34). For example,
DEF with a low concentration of urea may still provide NOX
emission reductions, but there may be a concern for protecting the SCR
system from damage if urea concentration is at or near zero as a
[[Page 43202]]
result of a fluid other than DEF being added to the DEF tank.
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\131\ See 40 CFR 1048.625.
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Second, in 40 CFR 1036.111(b), the EPA is proposing to specify that
systems must detect if urea concentration falls below a specified value
of 20 percent by weight.\132\ The EPA is proposing to allow
manufacturers to measure DEF quality either directly with a UQS or
indirectly with NOX sensors or other measurement of a
surrogate value. The EPA is proposing that this less precise detection
of DEF quality is appropriate because manufacturers are generally able
to apply compensation algorithms to account for varying DEF quality
above 20 percent. Resetting the threshold value for triggering a fault
condition based on DEF quality shifts the purpose of the fault
detection from the original approach of ensuring control relative to
DEF quality as an adjustable parameter to instead ensuring that
tampering has not occurred. The EPA is requesting comment on the
proposed threshold of 20 percent as the urea concentration at which
manufacturers would start to notify operators. (C-35).
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\132\ Engine manufacturers predominantly recommend use of DEF
meeting the industry-recognized ISO 22241-1:2019 quality standard.
This standard by the International Organization for Standardization
defines DEF as a water-based solution with a 32.5 percent urea
concentration. Available here: https://www.iso.org/standard/66408.html.
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Third, the EPA would not expect DEF quality to vary appreciably
between DEF refills. The EPA is therefore further proposing that DEF
quality detection may be limited to each time a refill event occurs to
further reduce inaccurate detection of DEF quality. The EPA is aware
that engines might not detect cases in which DEF quality has degraded
after sitting in the tank for several weeks if a truck is out of
service. The EPA is requesting comment on whether an additional DEF
quality check should occur after a specified number of days to address
concerns with DEF quality degradation during extended time out of
service. (C-36).
Fourth, measurement methods and operating characteristics can
substantially affect the time needed to determine urea concentration.
For example, extended high-load operation after a DEF refill would
allow the engine to stabilize DEF flow and NOX emissions to
quickly enable the evaluation of urea concentration. In contrast,
engines may need more time to achieve the right conditions for
evaluating urea concentration if there is extended idle. Requiring an
assessment of DEF quality within a certain time would introduce the
risk of forcing a premature judgment, which would increase the number
of instances of incorrectly warning operators that DEF quality is poor.
The EPA is therefore proposing to require that manufacturers use good
engineering judgment to assess DEF quality promptly after a DEF refill
event. The EPA is requesting comment on whether there are other
modifications needed to enable this proposal, such as to allow
temporary disablement of DEF compensation strategies to give
NOX sensors an opportunity to measure DEF quality without
the confounding effect of compensation. (C-37).
Fifth, the EPA is proposing changes related to testing.
Specifically, the EPA is proposing to amend 40 CFR 1036.501(b) to
establish a default expectation that laboratory testing (including OBD
certification testing) will involve DEF meeting nominal specifications
(32.5 0.7 percent urea). This approach is consistent with
measuring emissions using a test fuel that meets a standard
specification. The EPA is proposing to address varying DEF quality by
requiring compensation algorithms that adjust DEF flow and inducement
notifications for very low urea concentrations, rather than by
requiring manufacturers to demonstrate compliance with emission
standards over a range of urea concentrations. Note that this approach
for testing is also consistent with testing specifications that are
already established in 40 CFR 1065.735.
Sixth, the EPA is proposing to amend 40 CFR 1036.415(c) to perform
testing with the as-received DEF, with the allowance to add fresh DEF
as needed for completing the test run. Also, regardless of the as-
received DEF urea concentration, the vehicle must be tested in as-
received condition under the proposed amendment. Low-quality DEF would
not be a basis for invalidating a test. Manufacturers therefore would
determine the number of engines to test and would determine the pass-
fail result for the engine family based on test results including any
measurements with low-quality DEF. Manufacturers may flush the DEF
tank, refill with on-spec DEF and retest if the first test fails.
Results of any repeat testing with fresh DEF would not replace the
results from testing in the as-received condition, but the EPA would
consider the results of repeat testing in deciding whether or how to
pursue a compliance action.
A remaining question is whether the EPA should continue to treat
DEF quality as an adjustable parameter under 40 CFR 1036.115(f)(3).
Guidance documents have historically treated DEF quality as an
adjustable parameter based on the possibility of operators diluting DEF
with water. That consideration leads to the obligation for
manufacturers to comply with standards across the adjustable range.
With engines designed to derate performance based on poor quality DEF,
the urea concentration value used to initiate a derate for DEF quality
is also used to establish the practically adjustable range for
demonstrating compliance with standards. Implementing this requirement
has resulted in the issues raised in this section with DEF quality
inducements being a major source of frustration with operators. More
recently, the EPA issued revised guidance to alleviate some of the
problems resulting from the precise monitoring of DEF quality in-use
(see section V.B.4).\133\
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\133\ U.S. Environmental Protection Agency. (2026). ``DEF
Quality Monitoring Using Alternate Sensor Technologies,'' Guidance
Document: IACD-2026-05 (LDV, HDE, NRCI). www.epa.gov/system/files/documents/2026-03/iacd-2026-05-def-guidance-ltr-2026-0326.pdf.
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This proposal notes several relevant changes with respect to
treating DEF quality as an adjustable parameter. As described earlier
in this section, the EPA has a general expectation that operators will
fill DEF tanks with commercially available DEF, which should always be
very close to 32.5 percent urea concentration. Further, the EPA's
proposal to name below 20 percent urea concentration as the point for
triggering visible and/or audible notifications is intended to reduce
the precision needed to monitor DEF quality to address concerns about
accurately and consistently identifying poor DEF quality. The more
stringent NOX standard starting in MY 2027 further increases
the technical challenge of ensuring engines can be designed to tolerate
reasonable fluctuations in DEF quality such that operators are alerted
to actual DEF quality problems. The EPA's proposal in this section
addresses these concerns by specifying how DEF quality should be
treated for varying urea concentrations. This section also describes
the EPA's proposal to require manufacturers to design their engines
with compensation algorithms to achieve a comparable level of control
rather than keeping the open-ended requirement to meet standards at all
urea concentrations down to the onset of the inducement triggering
condition (20 percent urea). The combination of proposed provisions is
intended to address concerns about controlling emissions across a wider
range for DEF quality. These proposed provisions would have the effect
of shifting the
[[Page 43203]]
focus of compliance away from demonstrating at certification that
engines comply with standards across the adjustable range. For these
reasons, the EPA is requesting comment on whether DEF quality should
remain an adjustable parameter. (C-38).
In summary, high-quality DEF is widely available and operators have
little incentive to dilute DEF. The changes the EPA is proposing
related to DEF quality are intended to account for the fact that
current engine designs can generally compensate for real-world
fluctuations in DEF quality. The proposed revisions are intended to
properly focus on requiring that an engine's control system monitors
for, and alerts operators to, significant DEF quality issues while
limiting overly precise detection requirements that could lead to
frequent or improper notifications. Any actions the EPA can take to
reduce downtime would improve owner experiences operating and
maintaining heavy-duty engines and reduce the likelihood of occurrences
of tampering, which helps ensure in-use emission reductions. Due to
widespread DEF availability and familiarity with operators, the EPA
acknowledges that operators will readily find and continue to use high-
quality DEF.
2. DEF Freeze Protection Proposal
In 2009 guidance, CISD-09-04 Revised, the EPA discussed concern
that in cold weather DEF may freeze and not immediately flow to the SCR
system, which could reduce expected emission benefits.\134\ This
guidance stated that if DEF did not flow during such conditions, this
would fall under the EPA's Auxiliary Emission Control Device (AECD)
requirements (see 40 CFR 86.082-2). To meet the EPA's AECD
requirements, manufacturers must show they are not incorporating
strategies that reduce emission control effectiveness compared to
strategies used during applicable Federal testing procedures. The
guidance added that the EPA can examine an engine's SCR control system
during certification to ensure proper dosing will occur during extreme
cold ambient temperature conditions. This guidance stated that the EPA
expected manufacturers to either use a reducing agent (e.g., a form of
DEF) that would not freeze or design the SCR system to prevent freezing
through the use of heated components. The EPA included a test procedure
in this guidance that manufacturers could use to demonstrate adequate
DEF freeze protection. The procedure includes an expectation that DEF
would thaw and the SCR system should be fully functional within 70
minutes of engine starting. There are multiple reasons that cold
weather can lead to an inducement on existing engines, such as failure
of DEF heating components, false faults associated with DEF heating
components, and DEF that has not fully thawed that is incorrectly
judged by the UQS as being poor quality DEF. The EPA has heard from
operators and concerned citizens, specifically in Alaska, that their
extreme cold weather makes it difficult to avoid freezing DEF, and
their frequently remote operation increases the risk of serious
problems if trucks are derated.\135\ Recently, the Senate Environment
and Public Works Committee held a hearing to examine S. 3135, the Cold
Weather Diesel Reliability Act, legislation introduced by Senators Dan
Sullivan and Cynthia Lummis.\136\
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\134\ U.S. Environmental Protection Agency. (2009). CISD-09-04
Revised, ``Revised Guidance for Certification of Heavy-Duty Diesel
Engines Using Selective Catalyst Reduction (SCR) Technologies.''
https://dis.epa.gov/otaqpub/display_file.jsp?docid=20532&flag=1.
\135\ See docketed ``Email exchange with Nolan Willis'',
including a Petition for Conditional Delay and Alaska Exemption in
2027 Heavy-Duty Low-NOX Rule Reconsideration. Feb. 22,
2026.
\136\ U.S. Senate Environment and Public Works Committee. ``EPW
Committee Holds Hearing On Sullivan's Cold Weather Diesel
Reliability Act.'' Transcripts available here:
www.sullivan.senate.gov/imo/media/doc/ryan_anderson_testimony_03112026.pdf.
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The EPA did not modify or codify freeze protection test
requirements in the 2023 Final Rule. The EPA is proposing to amend 40
CFR 1036.115(i) to require manufacturers to include features that
provide freeze protection. That proposed codification would include
reference to a proposed procedure in 40 CFR 1036.560 for demonstrating
compliance for certification, consistent with the procedure established
in guidance. The EPA recognizes that SCR systems may not dose properly
in certain extreme cold ambient temperature conditions. The EPA is
requesting comment on whether there are changes that may improve the
freeze protection test procedure, such as more or less time in soak or
to thaw DEF, more or less time spent at idle, time at engine load, and
percent engine load, or if there is an alternative procedure that would
be more effective. (C-39).
The EPA is also proposing to amend 40 CFR 1036.111 to allow
manufacturers to temporarily disable the audible notifications proposed
in section V.C of this preamble when the ambient temperature is below
12 [deg]F (the freezing point of DEF). Under this proposed allowance,
manufacturers would be expected to restore the audible notifications
after ambient temperatures rise to a level that allows reliable system
monitoring. The EPA is proposing to require restarting audible
notifications for inducement triggering conditions when ambient
temperatures rise to 32 [deg]F for a given trip to provide sufficient
time for the system to stabilize. The EPA is proposing that audible
notifications would restart for the next key-on event if ambient
temperatures were above 12 [deg]F. The EPA requests comment on this
approach and other approaches the Agency should consider to address SCR
reliability in cold weather conditions, including but not limited to
application-based or geographic-based exemptions or different ambient
temperature thresholds.\137\ (C-40).
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\137\ See 40 CFR 85.1716 and 1039.670, which allow approval of
an emergency vehicle field modification to prevent engines with
aftertreatment from experiencing power loss when emission controls
are not working properly. See also 40 CFR 1036.655 and 1039.655,
which describe how diesel-fueled engines sold in American Samoa or
the Commonwealth of the Northern Mariana Islands are subject to less
stringent standards based on unreliable access to ultra-low-sulfur
diesel fuel. Less stringent standards for engines used in Alaska
would presumably be based on engine reliability in Arctic conditions
instead of or in addition to fuel constraints, but could otherwise
be implemented in the same way as the existing alternative standards
for these remote island territories.
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Also, the EPA is aware that some manufacturers may use DEF for
component protection external to the SCR system. Operating the engine
with frozen DEF may therefore cause problems of which operators should
be aware, aside from the usual concern about supplying DEF for catalyst
performance. The EPA requests comment on whether there is a need to
continue to require audible notifications to the operator to ensure
that they refill DEF or address other issues that may prevent DEF from
reaching those components in very cold weather. (C-41). The EPA is
aware that during very cold temperatures the engine's diagnostic system
can set false codes if DEF is unable to be thawed and injected, and is
proposing these changes such that operators can maintain confidence in
the engine's diagnostic system, to ensure the SCR system is not
damaged, and to reduce the possibility of tampering.
3. Proposed Changes to SCR-Based OBD Requirements
The EPA has heard from truck and engine manufacturers that there
are changes that can be made to existing OBD requirements that can help
eliminate false faults causing inducement and downtime that lead to
[[Page 43204]]
operator frustration. The EPA is proposing several OBD amendments
intended to improve SCR reliability. These proposed OBD changes are
important to maintain the integrity of the diagnostic system and the
MIL to ensure that operators are properly alerted to the need for
critical emission-related maintenance.
The first proposed amendment is to modify the in-use performance
monitoring ratio (IUMPR) requirements. The IUMPR is a ratio where the
numerator represents the number of times a monitor ran successfully and
the denominator represents the number of times a defined trip has
occurred. An IUMPR of 0.100 means a monitor must run on average
successfully one time out of 10 such trips. For heavy-duty diesel
engines, a trip is defined as an engine being started and operated for
at least 600 seconds where the engine is operated above 1150 rpm for at
least 300 seconds and idled for at least 30 seconds.\138\ The
denominator of the IUMPR for heavy-duty engines is incremented
(increased by one) for each trip, which could happen multiple times if
a vehicle makes a series of short trips where, for example, the engine
is started, idled for 30 seconds, driven for 10 minutes, and then
shutoff. If certain diagnostics or monitors cannot run successfully
during short trips, the numerator may not be incremented, and therefore
the IUMPR ratio would not be met. Long trips do not necessarily offset
problems meeting the IUMPR because numerators are not incremented more
than one time per trip and the UL for a heavy-duty diesel defined trip
is four hours with no key-off event. For example, to meet an IUMPR of
0.100 on average, a vehicle would need to take one long trip for every
nine short trips where a monitor was not able to run successfully.
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\138\ See Additional regulatory constraints include operation
must be at an elevation of less than 8,000 feet above sea level and
at an ambient temperature of greater than or equal to 20 degrees
Fahrenheit (-6.7 [deg]C). 13 CCR 1971.1 (d)(4.3.2)(B).
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The 2019 version of CARB OBD that the EPA incorporated by reference
in the 2023 Final Rule included an increase in the IUMPR from 0.100 to
0.300. This means that certain diagnostics must run successfully
approximately three out of every ten trips. For vehicles making a
series of short trips where a monitor cannot run successfully, one long
trip could be needed for every two short trips to meet the 0.300 IUMPR.
The real-world usage of commercial operators will not always be able to
meet the revised IUMPR, and without sufficient time to run diagnostics
there will be a risk of false faults occurring that frustrate
operators.
For vehicles taking very short trips, an IUMPR of 0.300 can mean on
average a monitor must run successfully three times in less than an
hour. During the development of CARB's 2019 OBD rule, CARB staff
believed that an IUMPR of 0.300 was technically feasible based on
manufacturers' data because CARB found that most monitors were able to
naturally run more frequently and meet a 0.300 ratio at that time.\139\
In CARB's analysis for this change, CARB said that manufacturers would
have to make little or no calibration change to meet a 0.300 IUMPR.
CARB added that typically only a single diagnostic needed recalibration
to meet a 0.300 IUMPR. However, CARB also noted that some monitors
would have difficulties in meeting the proposed ratio (e.g., nonmethane
hydrocarbon (NMHC) catalyst monitors) and included modified
requirements to enable these monitors to meet a 0.300 IUMPR.
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\139\ California Air Resources Board. (2018). Public hearing to
consider proposed revisions to on-board diagnostic system
requirements, including the introduction of real emissions
assessment logging (real), for heavy-duty engines, passenger cars,
light-duty trucks, and medium-duty vehicles and engines: Final
Statement of Reasons for Rulemaking, Including Summary of Comments
and Agency Response. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2018/hdobd18/fsor.pdf.
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Since the EPA adopted updated CARB 2019 OBD requirements in 2023,
the Agency has become concerned with the impacts on SCR reliability due
to the increase of the IUMPR. As a result of monitors needing to run
three times as often, manufacturers may not be able to wait for
conditions to be satisfactory and may need to trigger a fault condition
even if it is based on insufficient information, increasing the risk of
false failures that may have been preventable with additional
monitoring time. For example, there may not be sufficient time for the
DEF level to drop enough in a DEF tank for the system to reliably
recognize and characterize the change before making a pass/fail
decision on the proper functioning of the DEF level sensor. In this
example, the system could mistakenly interpret a lack of change in DEF
level to conclude that the DEF level sensor is not working properly,
which would trigger a fault condition and possibly an inducement. This
can create frustration for operators due to the increased potential for
false fault codes, which may add to some operators' impressions that
SCR systems are unreliable and risks operators losing confidence that
the MIL is an accurate indicator of serious problems that warrant
attention. The emissions benefit of this increased frequency of
monitoring is also unclear, as there are operational constraints that
limit how quickly an operator can pull over and respond to a dashboard
indication of an OBD fault condition. The EPA is therefore proposing to
restore the 0.100 IUMPR requirement for all monitors, which is
consistent with the Agency's heavy-duty OBD requirements that have been
in place since 2009.
Having an appropriate IUMPR value is even more important due to the
lower NOX standards effective in MY 2027, which may require
new emission control strategies and technologies (e.g., dual SCR or e-
heaters). Achieving an IUMPR of 0.300 may be possible for some
monitors, but will likely necessitate additional provisions to account
for cases in which it is not achievable when the new standards go into
effect. The proposal to restore the IUMPR requirement to 0.100 may
result in engines that over-comply in some cases (i.e., many monitors
will continue to naturally run more frequently), but would also provide
more stability for OBD system design as manufacturers deploy a mix of
technologies and diagnostic strategies to meet the more stringent
NOX standards.
The second proposed change in 40 CFR 1036.110(b) is to no longer
apply comprehensive component monitoring (CCM) requirements to
components or systems that provide input to inducement strategies. CCM
requires monitoring of electronic powertrain components or systems not
otherwise monitored for malfunction that either directly or indirectly
provide input to or receive commands from an on-board computer or smart
device that may affect emissions during any reasonable in-use driving
condition. These requirements add significant burden for manufacturers
to develop \140\ and test for failure modes that are unlikely to
improve in-use compliance but serve instead to increase operators'
impressions that SCR systems are unreliable. An example of how this
requirement may affect SCR reliability is by requiring rationality
monitoring of the DEF level sensor. Rationality monitoring is a
requirement to attempt to verify the accuracy of a signal while it is
in the range of normal operation and when it is compared to all other
available information, i.e., a check to see that the value makes sense
given current operating conditions. CCM can require manufacturers to
develop another monitor using a software algorithm to do rationality
checks on the DEF level sensor. This is usually in addition to
diagnostics that monitor the DEF level
[[Page 43205]]
sensor voltage reading for other abnormal readings which can indicate
wiring harness problems or a faulty sensor. As an example, this means
that even if a DEF tank is full, an operator could experience a fault
code and possibly an inducement if the rationality algorithm
incorrectly determines that the DEF level sensor is faulty. The EPA has
already established inducement triggering conditions in 40 CFR
1036.111. This redundancy only increases system complexity and the risk
of error. This proposal aims to further reduce the potential for
increased risk of false fault conditions. If the EPA finalizes the
proposal to replace inducements with visible and/or audible
notifications, this proposed change to CCM requirements will remain
important for maintaining the integrity of the diagnostic system and
notifying operators of serious issues. This proposal does not eliminate
monitoring for inducement-related components as described in section
V.C.2; these components would continue to be used to trigger visible
and/or audible notifications. The EPA is also requesting comment on
whether 40 CFR 1036.110 should be modified to acknowledge that, where
OBD requirements in the 2019 version of CARB's OBD with which the EPA
harmonized depend on inducements, engines meeting 40 CFR 1036.111 would
be considered to meet any inducement-related requirements included in
the Agency's OBD program. (C-42).
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\140\ See 13 CCR 1971.1 (g)(3).
---------------------------------------------------------------------------
The third proposed SCR-related change is to allow an increase in
the required time before the denominator must be incremented for
multiple catalyst aftertreatment architectures. The EPA recognizes that
there is a need to remove OBD barriers to certifying emission-control
systems with more than one catalyst. The EPA is proposing the same
amendment proposed by CARB in their November 2025 Omnibus Amendment
rule, which allows the denominator for systems with more than one
catalyst to be incremented using the criteria for emission controls
that experience infrequent regeneration events, in 13 CCR
1971.1(d)(4.3.2)(G).\141\ Ensuring that robust diagnostic decisions are
made can reduce the likelihood of false fault conditions.
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\141\ California Air Resources Board. (2025). Appendix A-1,
Proposed Amendments to Title 13 Regulation Order.
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The fourth proposed change is to provide relief to prevent
potential problems with readiness status of an OBD system that can
occur if a manufacturer chooses to use a newer OBD communication
protocol. Readiness is when an OBD system has stored enough information
that the system can indicate it is ready for a compliance test (e.g., a
test to meet inspection and maintenance requirements). The 2023 Final
Rule allowed manufacturers to choose whether they want to use the new
OBD J1979-2 communication protocol. However, to use this communication
protocol, manufacturers will need relief from readiness requirements
that were included in the 2019 version of CARB OBD that the EPA
adopted. This 2019 OBD program included a reorganization of how
monitors were grouped to establish readiness and can create readiness
errors resulting in vehicles being unable to pass inspection tests. The
EPA is proposing to adopt amendments that were included in CARB's 2022
OBD update to address these issues.
Fifth, the EPA is requesting comment on the need to clarify the
language in 40 CFR 1036.110(b) that states ``We may approve your
request to certify an OBD system meeting alternative specifications if
you submit information as needed to demonstrate that it meets the
intent of this section. For example, we may approve your request for a
system that meets a later version of CARB's OBD requirements if you
demonstrate that it meets the intent of this section.'' While this
example identifies later versions of CARB OBD requirements, the EPA did
not intend for this to preclude earlier versions of CARB OBD
requirements as allowable alternatives. The EPA also intended the term
``alternative specifications'' to mean, for example, parts of 13 CCR
1971.1 that differed from the version the Agency adopted in the 2023
Final Rule. The example provided in the regulatory section did not
intend for this to preclude selectively applying provisions from
different versions of CARB OBD requirements. (C-43).
Finally, in CARB's 2022 OBD update, industry expressed concern that
it is not technically feasible for the second and third NOX
sensors to fully meet the monitoring requirements, and that systems may
not be able to detect a sensor fault that prevents the SCR monitor from
detecting when one of the catalysts may be losing effectiveness.\142\
In CARB's response to comments document, CARB stated that the
requirements for NOX sensor monitoring only apply ``to the
extent feasible,'' therefore CARB did not see a need to provide
specific relief and did not provide any specific amendments to address
this concern. However, the EPA is concerned that, absent clear
requirements for systems with multiple catalysts, the existing
requirements will result in false pass and false fail monitoring
decisions. The EPA is therefore requesting comment on realistic
expectations for monitoring systems with multiple SCR catalysts and
NOX sensors and whether requirements need to be modified to
accommodate this new technology without driving false fault codes and
burdensome testing with little benefit to operators or the environment.
(C-44).
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\142\ NOX sensor monitoring requirements can be found
in 13 CCR 1971.1(e)(9.2.2)(D).
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E. Applying Proposed SCR Inducement Changes to Light-Duty Vehicles,
Medium-Duty Vehicles, and Nonroad Engines
Many aspects of the background and guidance described in this
section for highway heavy-duty engines apply equally to diesel-fueled
light-duty and medium-duty vehicles certified under 40 CFR part 86,
subpart S, and for nonroad compression-ignition engines certified under
40 CFR part 1039. For that reason, the owners and operators of these
SCR-equipped vehicles and equipment may also experience the in-use
frustrations with falsely triggered inducements and the impacts on
performance that the EPA has heard from highway heavy-duty vehicle
owners and operators. In particular, the EPA has heard from many owners
and operators of nonroad diesel equipment frustrated with DEF
inducements. For this reason, the EPA is also proposing regulatory
changes for new SCR-equipped light-duty and medium-duty vehicles and
for new SCR-equipped nonroad land-based diesel engines, as described in
this section. The EPA expects these proposed revisions to the Agency's
SCR inducement requirements for such vehicles and certain nonroad
equipment with diesel engines would only require software-based
changes, which are considered indirect costs associated with research
and development. See section 3.1.2 of the DRIA for this proposed rule
for a discussion on indirect costs. The EPA requests comment on any
costs or savings associated with these changes to light-duty, medium-
duty, and certain nonroad engines and equipment (i.e., development
costs to harmonize inducement requirements across vehicle classes). (C-
45). The EPA is also considering issuing new guidance related to the
SCR-equipped vehicles, engines, and equipment that have already been
certified by the EPA and are operating in the field, as described in
this section.
[[Page 43206]]
1. Certification Provisions for New Light-Duty and Medium-Duty Vehicles
Most of the light-duty and medium-duty vehicles with SCR sold today
are diesel-fueled pickup trucks and vans. These vehicles have been
designed with inducement features very similar to the derating
inducements for heavy-duty engines and may be unable to restart after
engine shutdown based on a detected fault condition.\143\ The updated
inducement provisions from the 2023 Final Rule were not applied to MYs
2027 and later light-duty and medium-duty vehicles, so those vehicles
remain subject to guidance recommendations. Until recently, the
guidance that applied to these vehicles recommended that manufacturers
derate speeds to 5 mph after detecting problems with DEF supply or
after detecting tampering. These vehicles are subject to the revised
guidance released in August of 2025, as described in section V.B.2 of
this preamble.
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\143\ U.S. Environmental Protection Agency. (2007).
``Certification Procedure for Light-Duty and Heavy-Duty Diesel
Vehicles and Heavy-Duty Diesel Engines Using Selective Catalyst
Reduction (SCR) Technologies,'' Guidance Document: CISD-07-07.
https://dis.epa.gov/otaqpub/display_file.jsp?docid=16677&flag=1.
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Light-duty vehicles are mostly personal vehicles; medium-duty
vehicles are often used in a commercial capacity. The operating
characteristics of light-duty and medium-duty vehicles are different
than heavy-duty vehicles in some ways, but the dynamic of depending on
the vehicle's diagnostic system to make an accurate assessment of the
lack of quality DEF or tampering and providing reasonable assurance
that the operator will supply quality DEF are similar to heavy-duty
vehicles. Some engines installed in medium-duty vehicles are certified
to heavy-duty engine requirements under 40 CFR part 1036 and will be
able to certify to the inducement provisions in 40 CFR 1036.111.
However, others that are nearly identical and perform similar functions
are certified differently and do not have analogous requirements under
40 CFR part 86. This different application of requirements to similar
vehicles can lead to confusion for operators, especially if these
vehicles are used for commercial purposes.
The list of inducement triggering conditions for heavy-duty engines
under 40 CFR 1036.111 is an example of what should apply equally for
light-duty and medium-duty vehicles. Limiting inducement triggering to
DEF supply, DEF quality, and certain types of fault conditions
associated with tampering is appropriate for light-duty and medium-duty
vehicles because they have the same technology and the same need to
ensure that operators perform scheduled maintenance with no tampering
of SCR-related hardware.
The EPA is therefore proposing to extend the proposed SCR-related
changes described for new highway heavy-duty engines earlier in this
section V to apply equally to light-duty and medium-duty vehicles
starting no later than MY 2029. The EPA adopted many of these
foundational elements in the 2023 Final Rule, including the specific
inducement triggering conditions and provisions allowing for owners to
reset systems without dealer involvement after correcting the problem.
In addition to those provisions from the 2023 Final Rule, the EPA is
proposing to rely on visible and/or audible notifications for all sizes
and types of motor vehicles. The proposed requirements for light-duty
and medium-duty vehicles would include the following main features,
most of which are referenced in 40 CFR 86.1810-17(l):
Specifying a schedule of visible and/or audible
notifications, instead of vehicle speed derates, to provide reasonable
assurance that operators take steps to provide a supply of quality DEF
in tanks (codified in 40 CFR 1036.111(c), with proposed amendments).
Specifying limited criteria that qualify as inducement
triggering conditions (codified in 40 CFR 1036.111(b), with proposed
amendments).
Codifying specifications related to the volume of DEF
tanks (codified in 40 CFR 1036.115(i)).
Requiring compensation algorithms to account for varying
DEF quality (proposed in 40 CFR 1036.115(i)).
Codifying protection from DEF freezing (proposed in 40 CFR
1036.115(i)).
Describing design specifications for visible and/or
audible notifications and for compensation algorithms in the
application for certification (proposed in 40 CFR 86.1844-01(d)).
The EPA is requesting comment on all aspects of this proposal to
codify provisions for ensuring proper maintenance of SCR systems used
with diesel-fueled light-duty and medium-duty vehicles regulated under
40 CFR part 86, subpart S, including the proposal to rely on visible
and/or audible notifications for SCR-related inducements. The request
for comment on amending the regulation for light-duty and medium-duty
vehicles also applies to all the issues and questions identified in the
discussion on inducements for heavy-duty engines in this section V. The
EPA is also requesting comment on whether chassis-certified medium-duty
vehicles that already meet 40 CFR 1036.111 should be required to meet
the in-cab display requirements in 40 CFR 1036.110. (C-46).
2. Certification Provisions for New Nonroad Diesel Engines
Nonroad diesel engines subject to standards under 40 CFR part 1039
are used in many different types of equipment with widely varying
operating characteristics, including for farming, construction,
industrial, and mining uses. These nonroad diesel engines are subject
to SCR-related inducements similar to the inducements that apply to
highway heavy-duty engines. Note that separate emission standards apply
to diesel engines used in locomotives (40 CFR part 1033) and in marine
vessels (40 CFR part 1042); diesel engines used in these other
applications are not subject to SCR-related performance derates and are
therefore not covered by this proposal.
In the 2023 Final Rule, the EPA did not extend the revised
inducement approach to nonroad diesel engines because those derate
schedules were inherently based on vehicle speed, which did not
translate easily to nonroad diesel engines for which vehicle speed is
not a useful measure of equipment performance. However, the approach
the EPA is proposing in this rule, to rely on visible and/or audible
notifications, creates a basis for proposing to adopt similar
provisions to prompt nonroad equipment operators to perform SCR-related
maintenance.
The EPA issued guidance in 2014 that described expectations for
ensuring nonroad engine and equipment operators used quality DEF,
including instructions for engine manufacturers to incorporate designs
to prevent equipment from operating after detecting problems with DEF
supply or DEF quality.\144\ The EPA provided examples in the 2014
guidance of effective final inducements to disable equipment and
prevent operators from being able to perform work, including completely
shutting the engine down or limiting the engine to idle with no power.
The 2014 guidance indicated an expectation that disablement would occur
within four hours of the triggering condition. For example, the 2014
guidance indicated that a final inducement for a combine harvester that
[[Page 43207]]
completely disables use of any implements may be an acceptable method
of preventing operators from being able to perform work, whereas a 40
percent engine derate would not be considered sufficient to prevent
operators from being able to perform work. Nonroad equipment can be
very difficult to transport to a repair facility. An alternative for
completely disabled engines is for a technician to travel to the
equipment for repair. Either of these remedies could be very expensive
and involve several days or weeks of downtime. The EPA also notes that
the problem may be caused by improper diagnosis from a defective
sensor, with the emission control system working properly the whole
time. Nonroad diesel engines were not subject to the inducement
provisions finalized in the 2023 Final Rule. However, nonroad diesel
engines were subject to the revised DEF inducement guidance released in
August of 2025, as described in section V.B.2 of this preamble, which
may still result in an idle-only inducement condition after a
lengthened time period. As described for highway heavy-duty engines,
these performance limitations are often caused by misdiagnosing a fault
condition, resulting in operator frustration from not being able to use
equipment as intended. Nonroad diesel equipment impacted by a
performance inducement can also have meaningful negative consequences
for the operators, owners, and businesses that rely on such equipment,
as well as others that rely on the productivity of such equipment
downstream, such as consumers.
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\144\ U.S. Environmental Protection Agency. (2014). Guidance
Document CISD-14-10, ``Certification of Nonroad Diesel Engines
Equipped with SCR Emission Controls.'' https://dis.epa.gov/otaqpub/display_file.jsp?docid=32298&flag=1.
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As described in the previous section for light-duty and medium-duty
vehicles, the list of inducement triggering conditions for heavy-duty
engines under 40 CFR 1036.111 is an example of what should apply
equally to nonroad diesel engines. Limiting inducement triggering to
DEF supply, DEF quality, and certain types of fault conditions
associated with tampering is appropriate for nonroad diesel engines
because they have the same technology and the same need to ensure that
operators perform scheduled maintenance with no tampering of SCR-
related hardware.
Given the similarity of the technology for highway and nonroad
engines, the EPA is proposing to extend the basic elements of the
proposed changes described in this section to nonroad diesel engines
with SCR starting no later than MY 2029. The proposed requirements
include the following main features:
Specifying a schedule of visible and/or audible
notifications, instead of approaches to prevent operators from being
able to perform work, to provide reasonable assurance that operators
take steps to provide a supply of quality DEF in tanks (40 CFR
1039.111(c)).
Specifying limited criteria that qualify as inducement
triggering conditions (40 CFR 1039.111(b)).
Codifying specifications related to the volume of DEF
tanks (40 CFR 1039.115(h)).
Requiring compensation algorithms to account for varying
DEF quality (40 CFR 1039.115(h)).
Codifying protection from DEF freezing (40 CFR
1039.115(h), with a reference to the measurement procedure in 40 CFR
1036.650).
Requiring engine manufacturers to give installation
instructions to equipment manufacturers related to SCR maintenance,
including the instruction to facilitate visible and/or audible
notifications on the operator interface for the equipment (40 CFR
1039.130(b)).
Describing design specifications for visible and/or
audible notifications and for compensation algorithms in the
application for certification (40 CFR 1039.205(b)).
One important distinction for nonroad equipment is the possibility
of operation without an operator present at all times. This includes
portable equipment, such as generators, fans, and compressors, as well
as autonomous vehicles, such as farm equipment. Visible and audible
notifications do not have the same meaning if there is no on-site (in-
cab) operator. On the other hand, anyone depending on the performance
of unattended equipment would need to be able to provide fuel and DEF
for continued operation, and would need to be able to respond if the
engine goes into a derate condition. Even unattended operation depends
on having an operator checking in periodically to add fuel (and DEF)
and otherwise ensure the equipment is working properly. In such a
circumstance, an operator would still be alerted to the need for
maintenance, but not as quickly as for equipment controlled directly by
an operator. Since the SCR-related maintenance is generally tied to
refueling intervals, the proposed visible and/or audible notifications
would still be expected to provide timely notification for maintaining
equipment for any SCR-related issues. The EPA requests comment on how
to design visible and/or audible notifications that would be effective
for unattended equipment operation. For example, engine manufacturers
may be able to facilitate a different kind of notification for
equipment manufacturers to incorporate into portable equipment,
especially with constant-speed engines. (C-47).
The EPA is requesting comment on all aspects of the proposal to
codify provisions for ensuring proper maintenance for SCR systems used
with nonroad diesel engines regulated under 40 CFR part 1039, including
the proposal to rely on visible and/or audible notifications for SCR-
related inducements. The request for comment on amending the regulation
for nonroad diesel engines also applies for all the issues and
questions identified in the discussion on inducements for new heavy-
duty engines in this section V. (C-48).
F. Potential for Additional EPA Inducement Guidance for In-Use Engines
and Vehicles
The August 2025 guidance described in section V.B.2 of this
preamble described a path for manufacturers to modify all types of in-
use diesel-fueled engines and vehicles with less severe inducements.
The guidance generally included recommendations allowing more operating
time before derates reach a point of preventing normal operation. As
part of the process of preparing the August 2025 guidance, the EPA
considered manufacturers' concerns that the control algorithms for in-
use engines provided very little flexibility to create a modified
strategy for timing and extent of derates.
Now that the EPA is proposing to replace derates with visible and/
or audible notifications for new engines and vehicles, there may be
greater flexibility to modify in-use engines to conform to the
inducement notifications described in this proposed rule. At the same
time, retrofitting in-use engines to include specific visible or
audible notifications may require a level of development and testing
that makes it unrealistic to expect a widespread practice of
retrofitting in-use engines or vehicles. Nevertheless, the EPA
anticipates that even limited retrofits would be a welcome upgrade for
those cases in which the manufacturer is able to support that
initiative. The EPA is therefore considering a process to issue updated
guidance that would allow manufacturers to modify in-use engines and
vehicles to switch from derates to visible and/or audible
notifications, consistent with any changes that the Agency adopts for
certifying new engines and vehicles for DEF-related inducements.
The EPA requests comment on the potential to retrofit in-use
engines and vehicles with visible and/or audible
[[Page 43208]]
notifications instead of performance derates. (C-49). The EPA also
requests comment on adapting any new guidance to accommodate
specialized concerns, such as operation in Alaska or other areas of
extreme cold as described in section V.D.2 of this preamble for highway
heavy-duty engines.
VI. Program Costs
The EPA used the same cost calculation methods as the 2023 Final
Rule but with updated inputs to reflect the proposed changes to the
emission-related warranty and useful life provisions of the 2023 Final
Rule. Detailed descriptions of the underlying data and methods of the
cost analysis are discussed in Chapter 3 of the DRIA for this proposed
rule. The EPA requests comment on the data and methods, including
estimated costs, cost savings, benefits, disbenefits, and transfers,
that were applied in the analyses for this proposed rule. The EPA is
also soliciting comment on the assumptions, modeling, and results of
potential cost savings and the associated increase in operational cost
increase for purchasers. (C-50).
The costs for the proposed amendments were updated for the action
and no-action cases to estimate the cost impacts. The EPA included all
the provisions of the 2023 Final Rule to estimate the costs of the no-
action case for this proposal and reduced the emission-related warranty
period for the action case. The updated costs reflect the expected
reduced emission-related warranty costs and changes to vehicle
operating costs, which include increased emissions repair costs and
reduced DEF costs.\145\ The change in emission-related warranty costs
and operating costs are estimated on a year-over-year basis and are
shown in Chapter 3.3. As described in section III.A of this proposal,
the EPA expects, in a competitive market, that engine manufacturers
will pass on most, if not all, of the warranty cost savings to the
purchaser of the vehicle, such that on net, the trucking industry,
including vehicle owners, should realize the total projected cost
savings of this action. There are no changes to direct manufacturing
costs between the proposed action case and no-action case. The EPA
projects that manufacturers have finished their technology designs for
MY 2027 engines, and the Agency believes that manufacturers are likely
to maintain a steady design for MY 2028 and MY 2029 and will not
redesign engines in response to the proposed shorter useful life
periods for only two years.
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\145\ The EPA projects a small increase in NOX
emissions from the proposed changes to emissions-related warranty
and regulatory useful life periods. DEF consumption is proportional
to NOX reduced by the SCR system, and the EPA has
projected a small decrease in DEF used due to the increase in
NOX emissions. Note that the EPA did not quantify any
potential change in NOX emissions as related to the
proposed change in SCR performance inducements.
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The cost impacts of this proposed rule are shown in Table VI-1 and
Table VI-2. These impacts include savings due to the reduced emission-
related warranty periods, increased operating costs, and a net cost
savings.
[[Page 43209]]
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[GRAPHIC] [TIFF OMITTED] TP14JY26.016
Table VI-3 shows the projected cost savings due to the proposed
shorter emission-related warranty period per vehicle for MY 2027 by
regulatory class and fuel type.
[[Page 43210]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.017
VII. Estimated Emissions Changes From the Proposed Program Amendments
The EPA projected an emissions impact associated with the proposed
revisions to emission-related warranty, regulatory useful life, and the
five percent production volume allowance. As described in detail in
section III of this preamble, the EPA proposes to shorten the emission-
related warranty periods for MYs 2027 and later engines to the levels
that apply to MYs 2026 and earlier and to delay implementation of the
extended useful life requirements for MYs 2027 and later engines until
MY 2030. These proposed changes would result in an increase in
NOX emissions from highway heavy-duty engines and vehicles
(about 4 to 12 percent, depending on the year), small increases in PM
and VOC (less than one percent), and a small increase in CO, as
described later in this section. These projected increases in emissions
from highway heavy-duty engines and vehicles are due to a higher level
of ``age-effects'' over the heavy-duty vehicle fleet lifespans.\146\
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\146\ For details of how MOVES accounts for changes in the
emission-related warranty and useful life provisions, refer to
Chapter 2.2.2 of the DRIA for this proposed rule.
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In addition, the EPA proposes to amend the five percent production
allowance for Heavy HDE in MYs 2027-2029. To account for this
allowance, MOVES emission rates for heavy heavy-duty vehicles (Class 8
and urban bus regulatory classes) are further adjusted by assuming five
percent of MYs 2027-2029 heavy heavy-duty vehicles would have emission
rates equivalent to pre-MY 2027 vehicles.
Section VII.A of this preamble provides an overview of the methods
used in MOVES to estimate emission changes under the proposed
revisions. Section VII.B of this preamble presents the projected
emission changes from the proposed amendments to 2023 Final Rule, with
additional detail in Chapter 2 of the DRIA for this proposed rule.
The EPA has not projected an emissions impact associated with the
proposed NCPs, consistent with the approach taken in all past NCP
rules. The EPA is not able to accurately project the degree to which
firms may make use of the NCPs. The EPA's expectation is that any use
of the NCPs would be temporary and short-lived, given the nature of
NCPs, which are a temporary bridge for any companies that need
additional time to bring engines into compliance with the MY 2027
NOX standards.
The EPA has also not projected an emissions impact associated with
the proposed revisions to the Agency's SCR inducement requirements for
heavy-duty diesel engines.147 148
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\147\ See the EPA's response to inducement-related comments in
section 8.1 (p 740) of the response to comments for the 2023 Final
Rule. ``Control of Air Pollution from New Motor Vehicles: Heavy-Duty
Engine and Vehicle Standards--Response to Comments''. December 2022.
EPA-420-R-22-036.
\148\ U.S. Environmental Protection Agency. (2021). ``Tampered
Diesel Pickup Trucks: A Review of Aggregated Evidence from EPA Civil
Enforcement Investigations.'' https://www.epa.gov/enforcement/tampered-diesel-pickup-trucks-review-aggregated-evidence-epa-civil-enforcement.
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The proposed amendments to the SCR inducement requirements would
further reduce operator frustrations with SCR emission controls, but
many uncertainties remain in terms of quantifying the potential impact.
As described in section V of this preamble, diesel vehicle owners and
operators have over a decade of experience using DEF, refilling DEF is
easy, and DEF is readily available at retail stores and diesel
refueling stations nationwide, which suggests operator access and
familiarity under the proposed amendments would not change DEF use
relative to today. Also, in section V of this preamble, the EPA
summarizes two recent studies on the impact of visible and audible
notifications used to prompt light-duty vehicle drivers to wear
seatbelts.149 150
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\149\ Kidd, D.G., and Singer, J. (2019). The effects of
persistent audible seat belt reminders and a speed-limiting
interlock on the seat belt use of drivers who do not always use a
seat belt. Journal of Safety Research. https://www.iihs.org/research-areas/bibliography/ref/2185.
\150\ Kidd, D.G., and O'Malley, S. (2023). Increasing seat belt
use in the United States by promoting and requiring more effective
seat belt reminder systems. Traffic Injury Prevention, 24(sup1),
S80-S87. https://doi.org/10.1080/15389588.2022.2134730.
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In this proposal, the ``no-action'' case represents the 2023 Final
Rule. It is unclear how owner or operator behavior would have changed
in response to the speed restrictions that were set to apply starting
in MY 2027 under the 2023 Final Rule. It is equally unclear how the
proposed new audible notification schedule would change behavior
relative to that no-action case.
At this time, the EPA is not able to accurately project the degree
to which SCR systems would be ineffective due to low DEF levels, low-
quality DEF, or component-level tampering that can lead to improper DEF
dosing, and therefore the Agency cannot project any associated increase
in emissions. The EPA is also unable to estimate whether the proposed
removal of derates under this proposal would result in a reduction in
emissions due reduced user frustration and fewer instances of in-use
tampering.
A. Emission Inventory Methodology
To estimate the emissions impacts of the proposed amendments to the
2023 Final Rule, the EPA used a regulatory version of the Agency's
MOVES model, known as MOVES5.R2.\151\ MOVES5.R2 is derived from the
latest public version (MOVES5) but includes several updates to vehicle
population and activity based on the latest information. Detailed
descriptions of the underlying data and analyses that informed the
model updates are discussed in Chapter 2.2 of the DRIA for this
proposed rule.
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\151\ See Chapter 2 of the ``Revision of Tier 4 Criteria
Pollutant Standards, Part 1: Amendments to Phase-In Schedule for
Light-Duty and Medium-Duty Vehicles--Draft Regulatory Impact
Analysis'' EPA-420-D-26-001. May 2026.
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First, the EPA modeled a baseline (no-action) scenario that retains
all provisions of the 2023 Final Rule. Then, the EPA modeled a control
(action) scenario to incorporate the proposed changes to the
provisions. The
[[Page 43211]]
emissions impacts of the proposed amendments were estimated by
calculating the emissions difference between the no-action and the
action cases. Inputs developed to model the national emission
inventories, including those representing the action case, are
discussed in Chapter 2.2.2 of the DRIA for this proposed rule.
B. Emission Inventory Impacts
As discussed in section III of this preamble, the proposed
amendments include modifications to the regulatory useful life and
emission-related warranty periods provisions, as well as the five
percent production allowance for MYs 2027-2029 heavy heavy-duty
vehicles, in the 2023 Final Rule. The combined emissions impacts of the
proposed revisions in calendar years 2030, 2040, 2045, and 2055 \152\
are presented in Table VII-1 (emissions changes in tons) and Table VII-
2 (percent changes relateive to the no-action case). The EPA also
evaluated the isolated effects of removing the longer emission-related
warranty periods and delaying the lengthened regulatory useful life by
three years. Because the proposed delay would shorten useful life
periods only for MY 2027 through MY 2029, and vehicles and fleet
turnover limits its influence, the EPA projects no impact on
NOX inventory from this proposed change in the analysis
years, with the exception of urban buses.\153\ Accordingly, all
NOX increases estimated in Table VII-1 are attributable to
the removal of the longer warranty periods.
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\152\ The 2023 Final Rule inventory analysis included calendar
years up to 2045. For the proposed amendments, the EPA extended
analysis years to 2055 to better estimate the impact of fleet
turnover further into the future.
\153\ Because urban buses have lower annual mileage than other
heavy-duty regulatory classes but a higher mileage limit (see Table
2-3 of the DRIA for this proposed rule), the shortened useful life
for MYs 2027-2029 urban buses would contribute only about a 0.02
percent increase to the heavy-duty NOX inventory in
calendar year 2040; no impact is projected for other analysis years.
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Using MOVES5.R2, the EPA estimates that the 2023 Final Rule, as
amended by this proposal, would continue to reduce the onroad heavy-
duty NOX inventory in 2055 by about 42 percent--over 260,000
tons of NOX--compared to the 2055 heavy-duty NOX
inventory without the 2023 Final Rule.\154\ The proposed amendments
would retain nearly 90 percent of the NOX reductions
originally projected to result from the 2023 Final Rule because the
more stringent standards and more representative test cycles finalized
in the 2023 Final Rule remain in place.
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\154\ Because this proposal and the 2023 Final Rule rely on
different versions of MOVES that incorporate updated underlying
data, the emissions estimates in this proposal are not directly
comparable to those presented in the 2023 Final Rule.
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Chapter 2.3.3 of the DRIA for this proposal includes additional
details on the emission changes by vehicle regulatory class. Chapter
2.4 of the DRIA for this proposal provides the estimates of year-over-
year criteria pollutant emissions for both the no-action and action
cases in calendar years 2027 through 2055.
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\155\ The EPA estimates no change in CO2 emissions
from the proposed revisions.
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[GRAPHIC] [TIFF OMITTED] TP14JY26.019
VIII. Air Quality Impacts of the Proposed Rule
Section VII of this preamble presents projections of the emissions
changes due to this proposed rule. When feasible and appropriate, the
EPA conducts full-scale photochemical air quality modeling to
accurately project levels of criteria and air toxic pollutants. For
this proposal, however, the EPA did not conduct air quality modeling to
determine how these emissions increases could change the ambient
concentrations of air pollutants. Making predictions about air quality
based solely on emissions changes is extremely difficult because the
atmospheric chemistry related to ambient concentrations of
PM2.5, ozone, and air toxics is very complex, and the
emissions changes are spatially variable. Nevertheless, considering the
air quality modeling conducted for the 2023 Final Rule, the projected
increase in total onroad emissions from the proposed amendments would
mean that the modeled air quality improvements from the 2023 Final Rule
would not be fully realized. The magnitudes of the onroad emissions
increases from the proposed amendments are smaller than the onroad
emissions reductions that were modeled for the 2023 Final Rule, so the
resulting changes in ambient concentrations of air pollutants are also
expected to be relatively smaller than what was previously modeled. The
EPA expects that the increased vehicle emissions would reduce the
estimated overall air quality improvements of the 2023 Final Rule on
ambient levels of ozone, PM2.5, NO2, and other
traffic-
[[Page 43212]]
related pollutants. Additional information, including information on
current air quality, is available in Chapter 4.1 of the DRIA for this
proposal.
IX. Projected Changes in Human Health and Welfare From the Proposed
Rule
Air pollutants emitted from the highway heavy-duty engines and
vehicles subject to the proposed rule impact public health, welfare,
and the environment. Motor vehicle emissions contribute to ozone,
PM2.5, and air toxics, which are linked to premature death
and other serious health impacts, including respiratory illness,
cardiovascular problems, and cancer. This air pollution affects people
nationwide, especially those who live or work near transportation
corridors. Detailed information on the health and welfare effects
associated with exposure to pollutants impacted by this proposed rule
can be found in sections II.B-C of the 2023 Final Rule preamble and
Chapter 4 of the 2023 Final Rule RIA.
The EPA sometimes performs air quality modeling to conduct a full
assessment of the PM2.5-related and ozone-related human
health benefits of the Agency's regulatory actions. As discussed in
section VIII of this preamble, the EPA did not conduct air quality
modeling for this proposal.
The EPA is obligated to present the Agency's best scientific
understanding and the implications of that science when developing
policies and regulations. However, historically, the EPA's analytical
practices may not have presented the full range of uncertainties and
associated confidence level regarding the potential benefit estimates
from reduction in exposure to PM2.5 and ozone. In addition,
the science regarding the exposure, health effects from exposure, and
valuation of reduction in health effects are evolving with better data
and methods, especially at low concentrations of PM and ozone. In past
regulatory analyses when the EPA did not conduct air quality modeling,
the Agency has used benefit per ton (BPT) values as a reduced-
complexity method to estimate the health benefits related to changes in
pollutant emissions. However, the EPA's use of BPT monetized values
introduces additional uncertainty. Although developed as a screening
tool when full-form photochemical modeling was not feasible, the BPT
approach reduces complex spatial and atmospheric relationships and may
be more suited to model emissions that are geographically more uniform
and for which the pollutant species are better mixed, thereby adding
uncertainty associated with those estimates. Some of the sources of
uncertainties include the set of assumptions used in projecting the
health impact of reducing PM. These projections are based on a series
of models that take into account emissions changes, the resulting
distributions of changes in ambient air quality, the estimated
reductions in health effects from changes in exposure, and the
composition of the population that will benefit from the reduced
exposure. Each component includes assumptions, each with varying
degrees of uncertainty.
In addition, the EPA historically provided point estimates rather
than just ranges of emission-related effects or only quantifying
emissions when monetizing proved to be too uncertain. Therefore, to
address these concerns, the EPA is refraining from providing primary
estimates resulting from changes in PM2.5 and ozone exposure
resulting from changes in direct PM2.5, NOX, and
VOC emissions but will continue to quantify the emissions until the
Agency is confident enough in the modeling to robustly monetize those
impacts.
A more robust description of the potential health and welfare
disbenefits associated with emissions increases due to the proposal is
contained in Chapter 5 of the DRIA for this proposed rule.
X. Economic Impact Analysis
This section describes the economic impact analysis of this
proposal. The analysis focuses on the potential impacts to vehicle
sales (including the number of vehicles sold and the timing of vehicle
purchases), the rate of replacement of used vehicles in the fleet with
new ones (fleet turnover), impacts on the shipping choices by heavy-
duty vehicle users (mode shift), and impacts on the choice of heavy-
duty class purchased (class shift).
In section VI of this preamble and Chapter 3 of the DRIA for this
proposed rule, the EPA estimates the net cost savings to manufacturers.
Manufacturers may pass on some, if not all, of the savings to vehicle
purchasers in the form of a lower-priced product. Basic economic theory
indicates that a decrease in purchase price due to decreased
manufacturer costs could lead to an increase in sales. Thus, the
manufacturer cost savings from this proposal could lead to some
increase in heavy-duty vehicle sales, but the size of the impact would
depend on the magnitude of the cost decreases and the degree to which
the cost decreases are passed on to vehicle purchasers.
As discussed in section VI of this preamble and Chapter 3.3.2 of
the DRIA for this proposed rule, the shortened emission-related
warranty period could shift some of the burden of repair costs from
manufacturers to users. Thus, purchasers could consider both an
increase in operating costs and any decrease in purchase price when
making a purchase decision. The EPA is unable to quantify these effects
because existing literature does not provide sufficient insight into
the relationship between emission-related warranty changes, increases
in prices due to increased emission-related warranty periods, and sales
impacts.
The EPA also considered how this proposal could affect the timing
of planned heavy-duty vehicle purchases in response to regulatory
changes, often referred to as the potential for ``pre-buy'' and ``low-
buy.'' Pre-buy occurs when a purchaser pulls ahead a planned future
purchase before implementation of a regulation in anticipation that a
future vehicle may have a higher upfront or operational cost or have
reduced reliability. Low-buy occurs when a vehicle that would have been
purchased before the implementation of a regulation is either not
purchased at all or the purchase is delayed after the implementation of
the regulation. Low-buy may occur directly as a function of pre-buy
(where a vehicle was instead purchased prior to implementation of the
new regulation) or due to a vehicle purchaser delaying the purchase of
a vehicle due to cost or uncertainty. Pre- and low-buy are short-term
effects, with research indicating that effects are seen for one year or
less before and after a regulation is implemented.\156\
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\156\ See the EPA report ``Analysis of Heavy-Duty Vehicle Sales
Impacts Due to New Regulation'' at https://cfpub.epa.gov/si/si_public_pra_view.cfm?dirEntryID=349838&Lab=OTAQ for a literature
review and EPA analysis of pre-buy and low-buy due to heavy-duty
regulations.
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In Chapter 10.1.1 of the 2023 Final Rule RIA, the EPA discussed
that purchase decisions and their timing related to a change in a
regulatory standards are affected by many factors, including
macroeconomic conditions, costs and timing of cost changes, and current
and predicted operating and maintenance costs.\157\ Given the current
industry-described stagnant freight market, the timing of this
proposal, the imminent release of the MY 2027 heavy-duty vehicles, and
other macroeconomic uncertainties, it is not clear whether there will
be any pre-buy associated with the 2023 Final Rule and what, if
[[Page 43213]]
any, impact this proposal would have on the timing of purchase
decisions.\158\
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\157\ U.S. Environmental Protection Agency. (2022) Control of
Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle
Standards, Regulatory Impact Analysis. EPA-420-R-22-035. See Chapter
10.1.1 on impacts to the timing of sales.
\158\ For example, see Heavy Duty Trucking, ``Goodbye, 2027
Truck Prebuy'' at https://www.truckinginfo.com/articles/goodbye-2027-truck-prebuy and Transport Topics, ``Uncertainty Dominated Pre-
Buy Discussion Ahead of 2027'' at https://www.ttnews.com/articles/uncertainty-pre-buy-trucks-2027.
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When there are measurably higher sales in a vehicle fleet, the EPA
typically expects an increase in fleet turnover. Vehicle purchasers may
replace older, less efficient vehicles with new, cleaner vehicles at a
faster rate. However, the EPA does not expect that any increase in
sales due to this proposal would be large enough to meaningfully affect
fleet turnover.
Transportation mode shift is a change from using a heavy-duty truck
to ship goods to using another mode of transportation (typically rail
or marine). Whether shippers switch to a different transportation mode
for freight depends not only on the cost per mile of the shipment
(freight rate), but also the value of the shipment, the time needed for
shipment, and the availability of supporting infrastructure. This
proposal is not expected to have an impact on truck freight rates given
that the price of the truck is only a small part of the cost per mile
of a ton of goods. The 2023 Final Rule did not anticipate mode shift
effects, and the EPA similarly does not expect mode shift effects from
this proposal.\159\
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\159\ U.S. Environmental Protection Agency. (2022) Control of
Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle
Standards, Regulatory Impact Analysis. EPA-420-R-22-035. See Chapter
10.1.4 for more information regarding mode shift.
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Class shift occurs when a vehicle purchaser decides to purchase a
different class of vehicle than originally intended due to a new
regulation. For example, a purchaser may buy a Class 8 vehicle instead
of the Class 7 vehicle they may have purchased in the absence of a
regulation. The EPA does not expect any class shift due to this
proposed rule.
XI. Summary of Requests for Comment in This Proposed Rule
While the EPA is not limiting comment on this proposed rule to
identified areas, the Agency is specifically soliciting comment on key
aspects of the proposed rule. To facilitate comment on those portions
of the rule, the EPA has indexed each comment solicitation with a
unique identifier below (e.g., ``C-1,'' ``C-2'') to provide a
consistent framework for effective and efficient solicitation of
comments. Accordingly, the EPA asks that commenters include the
corresponding identifier when providing comments relevant to that
comment solicitation by including the identifier either in a heading or
within the text of each comment. Specifically, the EPA is soliciting
comment on the following:
1. The EPA acknowledges that this proposal would, if finalized,
change the Agency's previous assessments in the 2023 Final Rule with
respect to the emission-related warranty, regulatory useful life, and
other program elements. The EPA believes that the revisions proposed in
this action relieve obligations in a manner that promotes compliance
and cost savings without undermining existing investments in
compliance. Nevertheless, the EPA requests comment on whether regulated
parties have any significant reliance interests with respect to the
changes in emission-related warranty, regulatory useful life, and other
program elements contained in this proposal. (C-1).
2. The EPA further understands that other interested parties may
have relied on the MY 2027 heavy-duty program for independent purposes,
including compliance with relevant National Ambient Air Quality
Standards (NAAQS) and related planning obligations, among others. The
EPA believes that the relatively small foregone emissions reductions
involved in this proposed revision, coupled with the relatively short
amount of time that has passed since promulgation of the 2023 Final
Rule, means that such interests do not supersede the Agency's
obligation to ensure that program elements are appropriate and reflect
technical and market realities. Moreover, the EPA notes that emissions
from mobile sources are just one consideration among many involved in
planning to attain the NAAQS and related obligations. Nevertheless, the
EPA requests comment on such reliance interests and how such interests
should be taken into account in any final action on this proposal. (C-
2).
3. The EPA requests comment on the nature and extent of any other
reliance interests that may arise from this proposed action and is
committed to assessing any such interests, determining whether they are
significant, and weighing such interests against competing rationales,
as required by law. (C-3).
4. The EPA is proposing two methods under a new interim provision
in 40 CFR 1036.150, which would apply to MY 2027 through MY 2029,
depending on whether the manufacturer conducted an emissions test at
the useful life periods that apply to MYs 2026 and earlier (e.g.,
equivalent 435,000-mile point for Heavy HDE) or only at the MYs 2027
and later useful life (e.g., equivalent 650,000 miles for Heavy HDE).
If available, the EPA is proposing under that interim provision that
manufacturers must use test data from the point that is equivalent to
the useful life periods that apply to MYs 2026 and earlier. If
manufacturers did not collect data at that point, the EPA would allow
manufacturers to interpolate their data to the shorter useful life
periods that apply to MYs 2026 and earlier using the data at the low-
hour and longer useful life test points. The EPA requests comment on
this interim provision. (C-4).
5. The EPA does not expect manufacturers who have products ready
for MY 2027 to change their emissions control technology plans for the
MYs 2027 through 2029 period because of this proposed change. However,
manufacturers that have not completed their durability demonstration
for the longer useful life may choose to stop the demonstration at the
current useful life values, which could result in a small reduction in
testing costs that manufacturers could pass on to their customers. For
this proposal, the EPA has taken a conservative approach to estimating
the cost impacts of the proposed change to useful life and found that
there would be no change in costs. The EPA requests comments on the
cost savings from this provision. (C-5).
6. The EPA requests comment on indefinitely keeping the MYs 2026
and earlier regulatory useful life periods for MYs 2027 and later. (C-
6).
7. The EPA requests comment on the proposed change to the MYs 2027-
2029 allowance under 40 CFR 1036.150(k), including whether it
appropriately balances the implementation needs and protection of
emissions benefits. The EPA also requests comment on whether this
flexibility should apply to fewer MYs (e.g., only MY 2027, or MYs 2027
and 2028), or more MYs (e.g., also MY 2030 or beyond). The EPA also
requests comment on whether the five percent cap should be lower or
higher, and if the cap should remain constant or phase down over time.
(C-7).
8. EPA requests comment on increasing the NOX FEL cap to
a level greater than 65 mg/hp[middot]hr, but less than or equal to the
MY 2026 standard of 200 mg/hp[middot]hr. The EPA also requests comment
on the number of MYs over which a higher FEL cap should apply,
including whether it is appropriate to not include an end date for a
higher FEL cap. For example, the EPA may consider a higher FEL cap for
a few MYs during the transition to the lower NOX standard
followed by a return to 65 mg/hp[middot]hr or
[[Page 43214]]
an alternative level, or a permanent increase in the FEL cap. The EPA
requests comment on the possible economic and emissions impacts of
allowing older credits to be used in the MYs 2027 and later program.
The EPA also requests comment on any reliance interest engine
manufacturers or others may have, including the specific reliance
concerns and available data which supports a reliance argument. (C-8).
9. The EPA also requests comment on whether, and how, banked
NOX emission credits earned prior to MY 2022 should be
allowed for use in MYs 2027 and later. A discount of up to 40 percent
is applied when using credits earned during MYs 2022-2026 for MYs 2027
and later, and the EPA requests comment on an appropriate discount that
could be applied to credits earned from the MYs 2004 to 2009 engines
for use in MYs 2027 and later. Finally, the EPA requests comment on the
possible economic and emissions impacts of allowing these older
NOX credits to be used in the MYs 2027 and later program.
The EPA also requests comment on any reliance interest engine
manufacturers or others may have, including the specific reliance
concerns and available data which supports a reliance argument. (C-9).
10. The EPA requests comment on whether and how emission credits
could be utilized between engine service classes. If the EPA were to
allow cross-averaging set NOX credit transfers, the Agency
requests comment on whether a credit discount should be applied, the
value of such a discount, and if that discount should be different
depending on which averaging set the credits are coming from. Finally,
the EPA requests comment on the possible economic and emissions impacts
of allowing credits to be used across averaging sets in the MYs 2027
and later program. The EPA also requests comment on any reliance
interest engine manufacturers or others may have, including the
specific reliance concerns and available data which supports a reliance
argument. (C-10).
11. The EPA recognizes that the three requests for comment in this
preamble section III.D. have potential interactions. For example, if
the EPA were to finalize all three elements (an increase in the
NOX FEL Cap, use of pre-MY 2022 NOX credits, and
movement of NOX credits across engine service classes) this
could reduce the compliance costs for some companies, while potentially
negatively impacting other companies due to a change in the competitive
landscape. The same is true if two of the three credit flexibilities
were included in the final rule, independent of the combination, as not
all companies have pre-MY2022 NOX credits, and not all HD
engine companies sell engines in multiple service classes. The EPA
requests comment on the potential interactions of these three credit
flexibilities, including the impacts on the overall emissions
reductions of the MY 2027 and later program, the costs of the program,
and any potential impacts on the competitive landscape for the
regulated industry. (C-11).
12. The 2023 Final Rule included a requirement at 40 CFR
1036.110(c)(1) for manufacturers to identify fault codes with an in-cab
display for any SCR- or diesel particulate filter (DPF)-related
condition causing the engine to initiate a speed reduction or torque
derate. First, the EPA is requesting comment on whether in-cab display
information requirements should remain part of the ``diagnostic
system.'' The required in-cab display information is not always part of
the OBD system which may complicate the usual standardization efforts
for diagnostic system elements. (C-12).
13. The EPA is considering a revision to 40 CFR 1036.530(c)(3)(iii)
to allow the existing exclusion of data during an infrequent
regeneration event to include any additional time needed for emissions
levels to return to normal baseline levels. The EPA adopted this change
for certification because the FTP, SET, and LLC duty cycles are
relatively short, and data from operation immediately following
regeneration may unrepresentatively bias measured emissions high on the
short certification cycles. The EPA requests comment on whether a
corresponding redefinition of the regeneration event is warranted for
off-cycle testing under 40 CFR 1036.530(c)(3)(iii). (C-13).
14. An earlier final rule included provisions allowing limited
numbers of qualified heavy-duty highway vehicles to have certified
engines meet alternative standards derived from the EPA's nonroad
engine programs.\160\ The provisions apply to amphibious vehicles,
vehicles with maximum operating speed of 45 mph or less, and all-
terrain vehicles with portal axles. The provisions also apply to hybrid
vehicles with engines that provide energy for an RESS. The EPA added a
sunset clause for hybrid vehicles at the end of MY 2027 based on the
expectation that greenhouse gas standards would lead to widespread
availability of engines certified with hybrid power systems to emission
standards under 40 CFR part 1036. The EPA is proposing to extend the
allowance to use the alternative standards through MY 2030. At the same
time, the EPA is proposing to reduce the annual limit on the number of
such vehicle manufacturers may produce from 1,000 to 200. This change
would treat specialty vehicles with hybrid powertrains the same as the
other types of specialty vehicles. The EPA accordingly requests comment
on the possible need to entirely remove the sunset on alternative
standards for engines installed in hybrid vehicles. Similarly, the EPA
requests comment on the need for a different limit on the annual number
of hybrid vehicles with engines certified to the alternative standards,
including maintaining the limit at 1,000. (C-14).
---------------------------------------------------------------------------
\160\ 80 FR 73478 (Oct 25, 2016).
---------------------------------------------------------------------------
15. Based on the available data, the EPA has determined that the
best methodological approach for this proposal is to rely on the
approach the Agency took in the 2023 Final Rule to determine the
incremental technology needed to meet the MY 2027 standards. In this
proposal, the EPA estimated COC50 and COC90 using
component cost data from the 2023 Final Rule's technology cost teardown
study of the aftertreatment systems of an engine meeting MY 2026
standards and one designed to meet the MY 2027 standards. As described
in the DTSD for this proposal, the EPA believes estimating the NCPs
based on public data that the Agency has already released through a
notice and comment process is a reasonable basis upon which to
determine compliance costs. The EPA is requesting comment on other data
sources and alternative methodologies based on other technology
packages manufacturers are developing to meet the MY 2027 standards.
(C-15).
16. The F factor is defined in existing 40 CFR 86.1113-87(a)(4) and
in the proposed new 40 CFR 1071.80(a) as the ratio of MC90
to MC50. To estimate the F factor, the EPA proposes to use
the ratio of COC90 to COC50, which reasonably
approximates the increase in MC90 over MC50 since
the EPA expects the marginal cost of compliance to scale with the
absolute cost of compliance. With this approach, the F factors for
Medium HDE and Heavy HDE are 1.176 and 1.093, respectively. Consistent
with the existing and new proposed definitions that limit F to values
between 1.1 and 1.3, the EPA proposes to round the F factor for Heavy
HDE up from 1.093 to 1.1. The EPA requests comment on whether the F
factor should be rounded to 1.1 or should be kept at 1.093. (C-16).
[[Page 43215]]
17. In this action, the EPA proposes to specify that the values in
Table IV-2 be used in the NCP formula for the MYs 2027 and later
NOX standard of 35 mg/hp[middot]hr for Medium HDE and Heavy
HDE. The complete derivation of these parameters is described in the
DTSD for this proposal. The EPA requests comment on the Agency's
estimates of these parameters. (C-17).
18. The EPA is also proposing to allow manufacturers to continue to
use approved deficiencies through MY 2029. These are important
considerations because it is likely that these engines would not be
able to comply with the EPA's revised OBD program, for example due to
the significant hardware and software changes needed to meet in-cab
display requirements. The EPA is requesting comment on whether the
Agency should consider modifying additional OBD provisions to
accommodate the certification of engines to the proposed NCP
requirements. (C-18).
19. The EPA is not basing the proposed NCP parameters on a
technology package with an e-heater, as the Agency only has one
publicly citable source for a cost estimate for the e-heater systems,
which has not gone through a public comment process and it is unclear
if that source has been peer reviewed. Nevertheless, the EPA presents
an estimate of NCPs based on the e-heater technology package in the
DTSD for this proposal. The EPA requests comment on whether to rely on
an e-heater technology package and requests references to other
publicly available data for the components of such a system. (C-19).
20. The approach of determining MC90 based on the
marginal cost between the upper limit and the standard that would
result in slopes of NCP versus compliance level that are constant at
$22 mg/hp[middot]hr and $38 mg/hp[middot]hr for Medium and Heavy HDE,
respectively. The EPA requests comment on using this approach for the
final rule. (C-20).
21. For this proposal, the EPA did not include local and State
sales tax or Federal excise tax in the NCP calculation. The EPA expects
that at least some portion of the NCPs will be passed on to the
customer in the final vehicle price, which will be taxed as applicable.
The EPA requests comment on this approach. (C-21).
22. For this proposal, the EPA included lifetime DEF costs in the
NCP values using a 7 percent discount rate. NCPs must be set at a level
to remove any competitive disadvantage for complying manufacturers, but
they are not intended to unduly penalize noncomplying manufacturers.
Considering the need to balance these two requirements, the EPA
requests comment on alternatively including DEF costs for only the
initial two to four years of an engine's life instead of the full
lifetime costs. (C-22).
23. Regarding the indirect costs, the EPA relied on the RPE values
for the ``heavy-duty truck industry,'' which is consistent with how the
Agency estimated the indirect costs in the 2023 Final Rule. The EPA
requests comment on this approach. An alternative to this approach
would be to use the indirect costs for heavy-duty engine or vehicle
manufacturers as shown in Table IV-3. The use of the indirect costs for
the heavy-duty truck manufacturer could be justified if it is
appropriate to assume that the markup for the truck dealers will
include a markup on the NCP. (C-23).
24. The proposed rule includes the equations from 40 CFR part 86,
subpart L, for calculating and applying the AAF to determine NCP
values. The AAF includes a term to increase NCP values over time, with
the goal of preventing manufacturers relying on NCPs as a long-term
compliance strategy. The AAF equation accounts for this by including a
years counter, i, as an exponent on the factor characterizing the
fraction of the engine fleet certified using NCPs. The EPA requests
comment on retaining the existing exponent and on two options to change
the Agency's historical approach. Retaining the existing exponent would
provide the most motivation for manufacturers to meet the standards in
later years without using NCPs. If it is likely that manufacturers will
continue to need additional time to meet the standards for a large
fraction of the engines in a class, another option could be to remove
the exponent from the AAF calculation, resulting in a standard
compounding rate that would avoid the NCPs becoming cost-prohibitive to
the point that certifying with NCPs is no longer a marketable option. A
second option could be to replace the exponent ``i'' with ``i-1,''
which would apply some accelerated compounding and aligns the
calculations with the existing approach of not having an AAF for the
first year. The EPA requests comment on these potential alternative
approaches. (C-24).
25. The EPA is proposing to isolate engines using NCPs into NCP
families that are separate from a manufacturer's averaging sets to
simplify the implementation and clearly distinguish which compliance
provisions apply to a given engine family. The EPA requests comment on
allowing NOX emission credits to be used in the NCP program.
A manufacturer could reduce the NCP for a given engine family if
NOX credits could be applied to that engine family to lower
the effective compliance level from which the NCP is calculated. The
EPA believes there may be an emissions benefit from this approach, as a
manufacturer would offset a portion of the emissions above the standard
with banked NOX emission credits earned from engines which
performed at a level below the NOX standard. The EPA notes
there would be an additional reporting and recordkeeping burden, for
both the manufacturer and the Agency, associated with tracking credit
use in addition to the proposed NCP provisions. The EPA also requests
comment regarding how NOX credits may impact the statutory
requirement that NCPs ``shall remove any competitive disadvantage to
manufacturers whose engines or vehicles achieve the required degree of
emission reduction.'' (C-25).
26. In this rule, the EPA is proposing to migrate the NCP
provisions to a new 40 CFR part 1071. In general, this migration is not
intended to change the compliance program specified in 40 CFR part 86,
except as specifically stated in this proposal. The EPA requests
comment on proposed provisions that are substantively different than
what applies under 40 CFR part 86, subpart L. In cases in which the EPA
is not proposing substantive changes to the regulation, the Agency
requests comment on those amendments as editorial changes. (C-26).
27. The EPA requests comment on the broader context of operator
frustration with inducements caused by defects rather than operator
behavior. In the wake of implementation of inducement schedules, strong
negative public sentiment toward DEF has emerged due to system failures
stemming from sources like failed sensors and the delayed availability
of replacement parts rather than inadequate DEF or an intent of
noncompliance. The EPA has heard from individuals who have experienced
traumatic events, such as lost harvests or stranded vehicles and
products. Observation and word-of-mouth have created secondary distrust
of SCR systems and DEF. The EPA is requesting comment on the extent to
which negative public sentiment has created a distrust associated with
SCR system and DEF failures and how to address the challenge of
rebuilding positive culture around the use of SCR systems and DEF. This
might take the form of educational outreach for manufacturers of
engines and manufacturers of emission-related
[[Page 43216]]
components to help operators learn how to practice better preventive
maintenance of vehicles to reduce the risk of component defects. This
might also take the form of additional engineering to focus on product
improvements for which defects are most common. (C-27).
28. The EPA expects these proposed revisions to the Agency's SCR
inducement requirements for heavy-duty diesel engines would require
software-based changes, which are considered indirect costs associated
with research and development. The EPA requests comment on any costs or
savings associated with these changes relative to the 2023 Final Rule
(i.e., software development costs or savings associated with removing
the 2023 Final Rule requirement to determine a vehicle's average speed
and then assign a specific derate schedule based on that speed). (C-
28).
29. The EPA is proposing to retain the provision in 40 CFR
1036.111(b)(1) that the first inducement notification will start three
hours prior to the tank becoming empty or when the tank is at 2.5
percent full. The EPA is requesting comment on whether this provision
should be retained, modified, or not included in revised inducement
requirements. (C-29).
30. The EPA is requesting comment on several aspects of the
proposed requirements for audible notifications as shown in Table V-1.
The EPA requests comment on advantages and disadvantages to creating a
separate audible notification schedule for DEF level. The EPA requests
comment on the audible notification length, including whether it should
last for more or less than 90 seconds each time. The EPA is requesting
comment on the frequency of the notifications, including whether more
or less frequent notifications would be appropriate for demonstrating
that operators are reasonably likely to take appropriate action,
including but not limited to whether the notification should be only at
key-on or if there should be a certain number of notifications during a
single trip. The EPA requests comment on whether audible notifications
are helpful in addition to visible notifications as a prompt for
operators to refill DEF or take other action to maintain SCR systems.
The EPA requests comment on whether visible notification should be
continuously illuminated or whether a flashing indicator would be more
effective. The EPA requests comment on whether visible and/or audible
notifications are inadequate for providing a reasonable assurance that
operators will provide a supply of quality DEF in tanks and not tamper
with SCR systems. The EPA requests comment on whether the regulation
should preserve a more modest schedule of performance derates than
specified in the 2023 Final Rule to prompt operators to take action or
derates similar to the schedules the Agency included in the August 2025
guidance. For example, the regulation could keep the derate schedule as
adopted in 40 CFR 1036.111 for low-speed, medium-speed, and high-speed
vehicles, but apply only one or two derate steps after detecting an
inducement triggering condition. Finally, the EPA requests comment on
whether changes to notifications and derates should lead the Agency to
include more or different criteria in the list of inducement triggering
conditions. (C-30).
31. The EPA is proposing to amend 40 CFR 1036.111(e) to replace
references to ``derates'' with ``visible and/or audible
notifications,'' and to remove paragraph (e)(3) that requires
restarting derates at the same point in the derate schedule for
inducement triggering conditions that recur after less than 40 hours of
engine operation. If the EPA retained paragraph (e)(3) for the audible
notification schedule in Table V-1, a recurring inducement condition
could trigger an audible notification at the final frequencies of one
notification every 1-3 hours. By removing the recurring fault
requirement, the proposed audible notifications would occur at the more
frequent initial levels. The EPA is requesting comment on whether this
provision should instead be retained or modified. (C-31).
32. The EPA is proposing to clarify that manufacturers may continue
to use engine derates to protect the engine or aftertreatment systems
from catastrophic damage. The EPA is requesting comment on whether this
proposal should be more or less restrictive. (C-32).
33. The EPA recognizes that manufacturers have been working toward
designing their heavy-duty diesel engines and vehicles with inducement
requirements as adopted in the 2023 Final Rule. This proposal retains
the general requirements specified in 40 CFR 1036.110 and 1036.111 for
MYs 2027 and 2028. The EPA requests comment on the potential need to
provide additional lead-time for implementing the proposed inducement
changes, specifically if the Agency should, instead, require this
change by MY 2030 or MY 2031. At the same time, the EPA is interested
in accelerating the change to the long-term approach described in this
proposal. Toward that end, the EPA requests comment on adjustments or
simplifications to the inducement provisions adopted in the 2023 Final
Rule that engine and vehicle manufacturers could apply before MY 2029,
considering the need for sufficient time to implement such changes. (C-
33).
34. The EPA is requesting comment on the feasibility of DEF dosing
continuing after a DEF quality warning is enacted (e.g., if the urea
concentration is less than 20 percent). For example, DEF with a low
concentration of urea may still provide NOX emission
reductions, but there may be a concern for protecting the SCR system
from damage if urea concentration is at or near zero as a result of a
fluid other than DEF being added to the DEF tank. (C-34).
35. In 40 CFR 1036.111(b), the EPA is proposing to specify that
systems must detect a fault condition if urea concentration falls below
a specified value of 20 percent by weight. The EPA is proposing to
allow manufacturers to measure DEF quality either directly with a UQS
or indirectly with NOX sensors or some other measurement of
a surrogate value. The EPA is proposing that this less precise
detection of DEF quality is appropriate because manufacturers are
generally able to apply compensation algorithms to account for varying
DEF quality above 20 percent. The EPA is requesting comment on the
proposed threshold of 20 percent as the urea concentration at which
manufacturers would start to notify operators. (C-35).
36. The EPA is requesting comment on whether an additional DEF
quality check should occur after a specified number of days to address
concerns with DEF quality degradation during extended time out of
service. (C-36).
37. The EPA is proposing to require that manufacturers use good
engineering judgment to assess DEF quality promptly after a DEF refill
event. The EPA is requesting comment on whether there are other
modifications needed to enable this proposal, such as to allow
temporary disablement of DEF compensation strategies to give
NOX sensors an opportunity to measure DEF quality without
the confounding effect of compensation. (C-37).
38. This proposal notes several relevant changes with respect to
treating DEF quality as an adjustable parameter. The EPA is requesting
comment on whether DEF quality should remain an adjustable parameter.
(C-38).
39. The EPA included a test procedure in guidance CISD-09-04R that
manufacturers could use to demonstrate adequate DEF freeze
[[Page 43217]]
protection. The EPA is proposing to include a requirement for
manufacturers to design their systems with freeze protection. The EPA
is requesting comment on whether there are changes that may improve the
freeze protection test procedure, such as more or less time in soak or
to thaw DEF, more or less time spent at idle, time at engine load, and
percent engine load, or if there is an alternative procedure that would
be more effective. (C-39).
40. The EPA is proposing to amend 40 CFR 1036.111 to allow
manufacturers to temporarily disable the audible notifications proposed
in section V.C of this preamble when the ambient temperature is below
12 [deg]F (the freezing point of DEF). Under this proposed allowance,
manufacturers would be expected to restore the audible notifications
after ambient temperatures rise to a level that allows reliable system
monitoring. The EPA is proposing to require restarting audible
notifications for inducement triggering conditions when ambient
temperatures rise to 32 [deg]F, and that this temperature allowance
should be revisited at each key-on event. The EPA requests comment on
this approach and other approaches the Agency should consider to
address SCR reliability in cold weather conditions, including but not
limited to geographic-based or application-based exemptions or
different ambient temperature thresholds. (C-40).
41. The EPA is aware that some manufacturers may use DEF for
component protection external to the SCR system. Operating the engine
with frozen DEF may therefore cause problems of which operators should
be aware, aside from the usual concern about supplying DEF for catalyst
performance. The EPA requests comment on whether there is a need to
continue to require audible notifications to the operator to ensure
that they refill DEF or address other issues that may prevent DEF from
reaching those components in very cold weather. (C-41).
42. The EPA is requesting comment on whether 40 CFR 1036.110 should
be modified to acknowledge that, where OBD requirements in the version
of CARB's OBD with which the EPA harmonized depend on inducements,
engines meeting 40 CFR 1036.111 would be considered to meet any
inducement-related requirements included in the Agency's OBD program.
(C-42).
43. The EPA is requesting comment on the need to revise the example
in 40 CFR 1036.110(b) that suggests the Agency may approve an OBD
system meeting a later version of CARB's OBD requirements as an
alternative specification such that it is not interpreted as precluding
earlier versions of CARB OBD requirements as allowable alternatives.
(C-43).
44. The EPA is concerned that, absent clear requirements for
systems with multiple catalysts, the existing requirements in CARB's
2022 OBD update will result in false pass and false fail monitoring
decisions. The EPA is therefore requesting comment on realistic
expectations for monitoring systems with multiple SCR catalysts and
NOX sensors and whether requirements need to be modified to
accommodate this new technology without driving false fault codes and
burdensome testing with little benefit to operators or the environment.
(C-44).
45. The EPA expects these proposed revisions to the Agency's SCR
inducement requirements for such vehicles and certain nonroad equipment
with diesel engines would only require software-based changes, which
are considered indirect costs associated with research and development.
See section 3.1.2 of the DRIA for this proposed rule for a discussion
on indirect costs. The EPA requests comment on any costs or savings
associated with these changes to light-duty, medium-duty, and certain
nonroad engines and equipment (i.e., development costs to harmonize
inducement requirements across vehicle classes). (C-45).
46. The EPA is requesting comment on all aspects of the proposal to
codify provisions for ensuring proper maintenance of SCR systems used
with diesel-fueled light-duty and medium-duty vehicles regulated under
40 CFR part 86, subpart S, including the proposal to rely on visible
and/or audible notifications for SCR-related inducements. The request
for comment on amending the regulation for light-duty and medium-duty
vehicles also applies to all the issues and questions identified in the
discussion on inducements for heavy-duty engines in section V of this
preamble. The EPA is also requesting comment on whether chassis-
certified medium-duty vehicles that already meet 40 CFR 1036.111 should
be required to meet the in-cab display requirements in 40 CFR 1036.110.
(C-46).
47. One important distinction for nonroad equipment is the
possibility of operation without an operator present at all times. This
includes portable equipment, such as generators, fans, and compressors,
as well as autonomous vehicles, such as farm equipment. The EPA
requests comment on how to design visible and audible notifications
that would be effective for unattended equipment operation. For
example, engine manufacturers may be able to facilitate a different
kind of notification for equipment manufacturers to incorporate into
portable equipment, especially with constant-speed engines. (C-47).
48. The EPA is requesting comment on all aspects of the proposal to
codify provisions for ensuring proper maintenance of SCR systems used
with nonroad diesel engines regulated under 40 CFR part 1039, including
the proposal to rely on visible and/or audible notifications for SCR-
related inducements. (C-48).
49. Now that the EPA is proposing to replace derates with audible
or visible notifications for new engines and vehicles, there may be
greater flexibility to modify in-use engines to conform to the
inducement notifications described in this proposed rule. At the same
time, retrofitting in-use engines to include specific visible or
audible notifications may require a level of development and testing
that makes it unrealistic to expect a widespread practice of
retrofitting in-use engines or vehicles. The EPA requests comment on
the potential to retrofit in-use engines and vehicles with visible and/
or audible notifications instead of performance derates. The EPA also
requests comment on adapting any new guidance to accommodate
specialized concerns, such as operation in Alaska or other areas of
extreme cold. (C-49).
50. The EPA requests comment on the data and methods, including
estimated costs, cost savings, benefits, disbenefits, and transfers,
that were applied in the analyses for this proposed rule. The EPA also
solicits comment on the assumptions, modeling, and results of potential
cost savings and the associated increase in operational cost increase
for purchasers. (C-50).
51. As described in section XII.J of this preamble, we note that
two referenced ASTM standards have been withdrawn: D2986-95a and F1471-
09. We request comment on continuing to use these withdrawn standards.
In particular, we request comment on referencing any alternative
methods to accomplish the intended purpose. (C-51).
XII. Statutory and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at www.epa.gov/laws-regulations/laws-and-executive-orders.
[[Page 43218]]
A. Executive Order 12866: Regulatory Planning and Review
This proposed action is an economically significant regulatory
action as defined under section 3(f)(1) of Executive Order 12866.
Accordingly, it was submitted to the Office of Management and Budget
(OMB) for review. Any changes made in response to Executive Order 12866
review have been documented in the docket, Docket ID No. EPA-HQ-OAR-
2026-0728.
The EPA prepared an analysis of the impacts of this proposal on
emissions and costs, which is described in detail in the DRIA for this
proposed rule. In the DRIA for this proposed rule, the EPA presents an
assessment of costs to regulated parties and other expected impacts of
the proposed rule.
With respect to costs, this proposal projects a net cost savings
when reduced warranty costs and operating costs are summed. The present
value of cost savings from 2027 to 2055, shown in Table XII-1, is
estimated to be $12 billion assuming a 3-percent discount rate and $9.4
billion assuming a 7-percent discount rate (2024 dollars). The
annualized value of cost savings from 2027 to 2055 is estimated to be
$640 million assuming a 3-percent discount rate and $770 million
assuming a 7-percent discount rate (2024 dollars). This analysis is
described further in section VI of this preamble and Chapter 3 of the
DRIA for this proposed rule.
[GRAPHIC] [TIFF OMITTED] TP14JY26.020
The proposed program amendments could result in increased emissions
(see section VII of this preamble and Chapter 2 of the DRIA for this
proposed rule). Increased emissions could also be associated with
impacts to air quality, human health, and welfare. As noted in section
IX of this preamble, the EPA did not quantify or monetize the health
effects associated with emissions changes. The monetized net benefits
associated with this proposal are therefore the cost savings presented
in Table XII-1. A qualitative description of the human health and
welfare effects related to emissions changes associated with this
proposal is provided in Chapter 5 of the DRIA for this proposed rule.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is expected to be an Executive Order 14192 deregulatory
action because the action is expected to result in cost savings.
C. Paperwork Reduction Act (PRA)
The information collection activities in this proposed rule have
been submitted for approval to OMB under the PRA. The Information
Collection Request (ICR) document that the EPA prepared has been
assigned EPA ICR number 7819.01, OMB Control Number 2060-NEW. You can
find a copy of the ICR in the docket for this rule, and it is briefly
summarized here.
The EPA is proposing targeted revisions to the 2023 Final Rule to
support implementation of the MYs 2027 and later heavy-duty engine
emissions program and to reduce the cost of the program. The proposed
changes include continuing the MYs 2026 and earlier warranty periods
for MYs 2027 and later engines, delaying the implementation of the MY
2027 useful life periods by three years, revising some targeted ABT
credit flexibilities, and revising the SCR inducement requirements for
diesel heavy-duty engines. These provisions do not have information
collection impacts as the information is already collected under EPA
ICR 1684.21, OMB Control Number 2060-0287, and EPA ICR 2621.02, OMB
Control Number 2060-0741. The EPA is also proposing discrete revisions
to correct and/or clarify certain identified regulatory provisions,
which also do not have information collection impacts. Finally, the EPA
is proposing to make NCPs available for MY 2027 Medium HDEs and Heavy
HDEs. NCPs allow manufacturers to introduce into commerce engines that
fail to conform to certain emission standards upon payment of a
monetary penalty. The information collection impacts of this program
element are described below and in greater detail in the draft ICR
Supporting Statement, which can be found in the docket for this rule.
Respondents/affected entities: Manufacturers of Medium HDE and
Heavy HDE.
Respondent's obligation to respond: Regulated entities must respond
to this collection if they wish to sell their products in the United
States, as prescribed by CAA section 203(a). This rule proposes to
relieve manufacturers of the burden to provide certain information to
the EPA as part of their annual MY vehicle certification under CAA
section 208(a), which is required prior to entering vehicles into
commerce. Participation in some programs is voluntary, but once a
manufacturer has elected to participate, it must submit the required
information.
Estimated number of respondents: 2.
Frequency of response: Annually or on occasion, depending on the
type of response.
Total estimated burden: 282 hours (per year). Burden is defined at
5 CFR 1320.3(b).
Total estimated cost: $84,285 per year, which includes an estimated
$50,870 from the combination of annualized capital and operation and
maintenance costs, and $33,415 for labor costs.
An agency may not conduct or sponsor, and a person is not required
to respond to, an ICR unless it displays a currently valid OMB control
number. The OMB control numbers for the EPA's regulations in 40 CFR are
listed in 40 CFR part 9.
Submit your comments on the EPA's need for this information, the
accuracy of the provided burden estimates, and any suggested methods
for minimizing respondent burden to the Agency using the docket
identified at the beginning of this proposed rule. The EPA will respond
to any ICR-related comments in the final rule. You may also send your
ICR-related comments to OMB's Office of Information and Regulatory
Affairs using the interface at http://www.reginfo.gov/public/do/PRAMain. Find this particular ICR by selecting ``Currently under
Review--Open for Public Comments'' or by using the search function. OMB
must receive comments no later than August 13, 2026.
[[Page 43219]]
D. Regulatory Flexibility Act (RFA)
I certify that this proposed action would not have a significant
economic impact on a substantial number of small entities under the
RFA. In making this determination, the EPA concludes that the impact of
concern for this rule is any significant adverse economic impact on
small entities and that the Agency is certifying that this proposed
rule will not have a significant economic impact on a substantial
number of small entities because the rule relieves regulatory burden on
the small entities subject to the rule.
The regulated entities that are subject to the regulations the EPA
is proposing to revise in this rule are heavy-duty engine
manufacturers, alternative fuel converters, and independent commercial
importers subject to criteria emissions standards for engines. Vehicle
manufacturers that add features to incomplete vehicles are not subject
to the proposed regulations because the incomplete vehicles they are
finishing are already certified. Therefore, these vehicle manufacturers
are not subject to the standards. The EPA identified two small
alternative fuel engine converters subject to the proposed rule; none
of the eleven engine manufacturers or importers subject to the rule are
small. The EPA is certifying that this proposed action would not have a
significant economic impact on a substantial number of small entities
because the proposed action would relieve regulatory burden on all
entities, including all small entities, subject to the current rules.
The proposed changes include shortening emission-related warranty
periods, delaying increased regulatory useful life periods, and
simplifying engine DEF inducement requirements. The proposal also
includes two flexibility provisions, production volume allowances and
NCPs, that would also reduce costs. Finally, the proposed regulatory
amendments clarify and streamline various regulatory provisions. The
EPA does not anticipate that there would be any significant adverse
economic impact on directly regulated small entities as a result of
these revisions. The EPA has therefore concluded that this proposed
action would, if finalized, relieve regulatory burden for all directly
regulated small entities.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain an unfunded mandate of $100 million or
more (in 1995 dollars) as described in UMRA, 2 U.S.C. 1531-1538, and
does not significantly or uniquely affect small governments. This
action imposes no enforceable duty on any State, local, or Tribal
governments. Requirements for the private sector do not exceed $100
million in any one year.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the States, the relationship between the
national government and the States, or the distribution of power and
responsibilities among the various levels of government.
G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This proposed action would not have Tribal implications as
specified in Executive Order 13175. This proposed action includes
targeted amendments to the EPA's heavy-duty highway engine regulations
for MY 2027 and later, and proposes to make NCPs available to
manufacturers of Medium HDE and Heavy HDE beginning in MY 2027. In
addition, the EPA proposes to amend the requirements for SCR system
inducement provisions for newly manufactured diesel-fueled highway
engines and vehicles (i.e., light- and medium-duty vehicles and heavy-
duty engines) and nonroad engines and equipment. If finalized, it would
not have substantial direct effects on Tribal governments, the
relationship between the Federal government and Indian Tribes, or the
distribution of power and responsibilities between the Federal
government and Indian Tribes, as specified in Executive Order 13175.
Thus, Executive Order 13175 does not apply to this proposed action.
However, consistent with the EPA's Policy on Consultation and
Coordination with Indian Tribes, the Agency plans to continue engaging
with Tribal stakeholders in the development of this rulemaking by
offering government-to-government consultation upon request.
H. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
Executive Order 13045 directs Federal agencies to include an
evaluation of the health and safety effects of proposed regulations on
children in Federal health and safety standards and explain why the
regulation is preferable to potentially effective and reasonably
feasible alternatives. This action is subject to Executive Order 13045
because it is an economically significant regulatory action under
Executive Order 12866 section 3(f)(1) and the EPA believes the
environmental health or safety risks of the pollutants impacted by this
action may have a disproportionate effect on children. Accordingly, the
EPA evaluated the environmental health or safety effects on children of
air pollutants affected by this action.
Children are not expected to experience greater ambient
concentrations of air pollutants than the general population. However,
children are more susceptible than adults to air pollution and children
tend to spend increased time outdoors. Children make up a substantial
fraction of the United States population and often have unique factors
that contribute to their increased risk of experiencing a health effect
from exposures to ambient air pollutants because of their continuous
growth and development. Children are more susceptible than adults to
many air pollutants because they have (1) a developing respiratory
system, (2) increased ventilation rates relative to body mass compared
with adults, (3) an increased proportion of oral breathing,
particularly in boys, relative to adults, and (4) behaviors that
increase chances for exposure. Even before birth, the developing fetus
may be exposed to air pollutants through the mother that affect
development when the mother is exposed. A qualitative description of
the human health and welfare effects related to emissions changes
associated with this proposal is provided in Chapter 5 of the DRIA for
this proposed rule. Furthermore, the Policy on Children's Health also
applies to this action.
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution, or use of energy. Further, the EPA has concluded that
this action is not likely to have any adverse energy effects because
these amendments generally are intended to reduce the regulatory costs,
support the implementation of new regulatory requirements, add clarity
to the regulatory compliance provisions and correct errors in the
regulations.
J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR
Part 51
This action involves technical standards. The EPA proposes to use
new or updated standards from ASTM International, the American National
Standards Institute, and SAE International, as described in the tables
[[Page 43220]]
of this section. Except for the standards discussed in this section,
the standards included in the regulatory text as incorporated by
reference were all previously approved for incorporation by reference
and no change is included in this action.
In accordance with the requirements of 1 CFR 51.5, the EPA is
proposing to incorporate by reference the use of certain standards and
test methods from ASTM International. The referenced standards and test
methods may be obtained from ASTM International, 100 Barr Harbor Drive,
P.O. Box C700, West Conshohocken, PA, 19428-2959, (610) 832-9585, or
www.astm.org. The EPA is proposing to incorporate by reference the
following standards from ASTM International:
BILLING CODE 6560-50-P
[[Page 43221]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.021
[[Page 43222]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.022
[[Page 43223]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.023
[[Page 43224]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.024
BILLING CODE 6560-50-C
If ASTM adopts an updated version of the referenced standards, the
EPA would expect to reference the most recent version in the final
rule. We note, however, that we intend to maintain consistency in the
referenced versions of ASTM documents that also appear in 40 CFR part
1090, which establishes standards for in-use gasoline and diesel fuel.
The overlapping ASTM standards include: D86, D975, D976, D1298, D1319,
D2163, D2622, D3231, D3237, D4052, D5186, D5191, D5453, D5599, D5769,
D6550, D6667. We also note that two referenced ASTM standards have been
withdrawn: D2986-95a and F1471-09. We request comment on continuing to
use these withdrawn standards. In particular, we request comment on
referencing any alternative methods to accomplish the intended purpose.
(C-51).
In accordance with the requirements of 1 CFR 51.5, the EPA is
proposing to incorporate by reference the use of certain standards and
test methods from the American National Standards Institute (ANSI). The
referenced standards and test methods may be obtained from ANSI, 25 W
43rd Street, 4th Floor, New York, NY 10036, (212) 642-4900, or
www.ansi.org. The EPA is proposing to incorporate by reference the
following standard from ANSI:
[GRAPHIC] [TIFF OMITTED] TP14JY26.025
In accordance with the requirements of 1 CFR 51.5, the EPA is
proposing to incorporate by reference the use of certain standards and
test methods from SAE International. The referenced standards and test
methods may be obtained from SAE International, 400 Commonwealth Dr.,
Warrendale, PA 15096-0001, (877) 606-7323 (U.S. and Canada) or (724)
776-4970 (outside the U.S. and Canada), or www.sae.org. The EPA is
proposing to incorporate by reference the following standard from ASTM
International:
[GRAPHIC] [TIFF OMITTED] TP14JY26.026
The following standards appear in the amendatory text of this
document and have already been approved for the locations in which they
appear: 13 CCR 1968.2, 13 CCR 1971.1, NIST Technical Note 1297. No
changes are proposed to the IBR material.
XIII. Statutory Provisions and Legal Authority
Statutory authority for this proposed action comes from the CAA (42
U.S.C. 7401-7675).
List of Subjects
40 CFR Part 86
Environmental protection, Administrative practice and procedure,
Confidential business information, Incorporation by reference,
Labeling, Motor vehicle pollution, Reporting and recordkeeping
requirements.
40 CFR Part 1036
Environmental protection, Administrative practice and procedure,
Air pollution control, Confidential business information, Greenhouse
gases, Labeling, Incorporation by reference, Motor vehicle pollution,
Reporting and recordkeeping requirements, Warranties.
40 CFR Part 1037
Environmental protection, Administrative practice and procedure,
Air pollution control, Confidential business information, Incorporation
by reference, Labeling, Motor vehicle pollution, Reporting and
recordkeeping requirements, Warranties.
[[Page 43225]]
40 CFR Part 1039
Administrative practice and procedure, Air pollution control,
Confidential business information, Imports, Labeling, Penalties,
Reporting and recordkeeping requirements, Warranties.
40 CFR Part 1065
Environmental protection, Administrative practice and procedure,
Air pollution control, Incorporation by reference, Reporting and
recordkeeping requirements, Research.
40 CFR Part 1071
Environmental protection, Administrative practice and procedure,
Air pollution control, Penalties, Reporting and recordkeeping
requirements.
Lee Zeldin,
Administrator.
For the reasons stated in the preamble, the U.S. Environmental
Protection Agency proposes to amend title 40, chapter I, of The Code of
Federal Regulations as follows:
PART 86--CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES
AND ENGINES
0
1. The authority citation for part 86 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
2. Amend Sec. 86.1 by revising the introductory text and paragraphs
(a) and (b) to read as follows:
Sec. 86.1 Incorporation by reference.
Certain material is incorporated by reference into this part with
the approval of the Director of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, EPA must publish a document in the Federal
Register and the material must be available to the public. All approved
incorporation by reference (IBR) material is available for inspection
at EPA and at the National Archives and Records Administration (NARA).
Contact EPA at: U.S. EPA, Air and Radiation Docket Center, WJC West
Building, Room 3334, 1301 Constitution Ave. NW, Washington, DC 20004;
www.epa.gov/dockets; (202) 202-1744. For information on inspecting this
material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from the following sources:
(a) ASTM International (ASTM). ASTM International, 100 Barr Harbor
Drive, P.O. Box C700, West Conshohocken, PA, 19428-2959; (610) 832-
9585; www.astm.org
(1) ASTM C1549-09, Standard Test Method for Determination of Solar
Reflectance Near Ambient Temperature Using a Portable Solar
Reflectometer, approved August 1, 2009 (``ASTM C1549''); IBR approved
for Sec. 86.1869-12(b).
(2) ASTM D86-23ae2, Standard Test Method for Distillation of
Petroleum Products at Atmospheric Pressure, approved December 1, 2023
(``ASTM D86''); IBR approved for Sec. Sec. 86.113-04(a); 86.113-94(b);
86.213(a); 86.513(a).
(3) ASTM D93-26, Standard Test Methods for Flash Point by Pensky-
Martens Closed Cup Tester, approved March 1, 2026 (``ASTM D93''); IBR
approved for Sec. 86.113-94(b).
(4) ASTM D445-24, Standard Test Method for Kinematic Viscosity of
Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity),
approved April 1, 2024 (``ASTM D445''); IBR approved for Sec. 86.113-
94(b).
(5) ASTM D613-25a, Standard Test Method for Cetane Number of Diesel
Fuel Oil, approved November 1, 2025 (``ASTM D613''); IBR approved for
Sec. 86.113-94(b).
(6) ASTM D975-24a, Standard Specification for Diesel Fuel Oils,
approved August 1, 2024 (``ASTM D975''); IBR approved for Sec.
86.1910(c).
(7) ASTM D976-21e1, Standard Test Method for Calculated Cetane
Index of Distillate Fuels, approved November 1, 2021(``ASTM D976'');
IBR approved for Sec. 86.113-94(b).
(8) ASTM D1319-20a, Standard Test Method for Hydrocarbon Types in
Liquid Petroleum Products by Fluorescent Indicator Adsorption, approved
August 1, 2020 (``ASTM D1319''); IBR approved for Sec. Sec. 86.113-
04(a); 86.213(a); 86.513(a).
(9) ASTM D1945-25, Standard Test Method for Analysis of Natural Gas
by Gas Chromatography, approved December 1, 2019 (``ASTM D1945''); IBR
approved for Sec. Sec. 86.113-94(e); 86.513(d).
(10) ASTM D2163-23e1, Standard Test Method for Determination of
Hydrocarbons in Liquefied Petroleum (LP) Gases and Propane/Propene
Mixtures by Gas Chromatography, approved March 1, 2023 (``ASTM
D2163''); IBR approved for Sec. Sec. 86.113-94(f).
(11) ASTM D2622-24, Standard Test Method for Sulfur in Petroleum
Products by Wavelength Dispersive X-ray Fluorescence Spectrometry,
approved July 1, 2024 (``ASTM D2622''); IBR approved for Sec. Sec.
86.113-04(a); 86.113-94(b); 86.213(a); 86.513(a).
(12) ASTM D2699-25, Standard Test Method for Research Octane Number
of Spark-Ignition Engine Fuel, approved November 1, 2025 (``ASTM
D2699''); IBR approved for Sec. Sec. 86.113-04(a); 86.213(a).
(13) ASTM D2700-26, Standard Test Method for Motor Octane Number of
Spark-Ignition Engine Fuel, approved May 1, 2026 (``ASTM D2700''); IBR
approved for Sec. Sec. 86.113-04(a); 86.213(a).
(14) ASTM D3231-25, Standard Test Method for Phosphorus in
Gasoline, approved May 1, 2025 (``ASTM D3231''); IBR approved for
Sec. Sec. 86.113-04(a); 86.213(a); 86.513(a).
(15) ASTM D3237-22, Standard Test Method for Lead in Gasoline by
Atomic Absorption Spectroscopy, approved October 1, 2022 (``ASTM
D3237''); IBR approved for Sec. Sec. 86.113-04(a); 86.213(a);
86.513(a).
(16) ASTM D4052-22, Standard Test Method for Density, Relative
Density, and API Gravity of Liquids by Digital Density Meter, approved
May 1, 2022 (``ASTM D4052''); IBR approved for Sec. 86.113-94(b).
(17) ASTM D5186-24, Standard Test Method for Determination of the
Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels and
Aviation Turbine Fuels by Supercritical Fluid Chromatography, approved
July 1, 2024 (``ASTM D5186''); IBR approved for Sec. 86.113-94(b).
(18) ASTM D5191-22, Standard Test Method for Vapor Pressure of
Petroleum Products (Mini Method), approved July 1, 2022 (``ASTM
D5191''); IBR approved for Sec. Sec. 86.113-04(a); 86.213(a);
86.513(a).
(19) ASTM D5769-25, Standard Test Method for Determination of
Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas
Chromatography/Mass Spectrometry, approved October 1, 2025 (``ASTM
5769''); IBR approved for Sec. Sec. 86.113-04(a); 86.213(a);
86.513(a).
(20) ASTM D6550-25, Standard Test Method for Determination of
Olefin Content of Gasolines by Supercritical-Fluid Chromatography,
approved October 1, 2025 (``ASTM D6550''); IBR approved for Sec. Sec.
86.113-04(a); 86.213(a); 86.513(a).
(21) ASTM E29-93a, Standard Practice for Using Significant Digits
in Test Data to Determine Conformance with Specifications, approved
March 15, 1993 (``ASTM E29''); IBR approved for Sec. Sec. 86.004-
15(c); 86.007-11(a); 86.007- 15(m); 86.1803-01.
(22) ASTM E903-96, Standard Test Method for Solar Absorptance,
Reflectance, and Transmittance of Materials Using Integrating Spheres,
approved April 10, 1996 (``ASTM E903''); IBR approved for Sec.
86.1869-12(b).
[[Page 43226]]
(23) ASTM E1918-06, Standard Test Method for Measuring Solar
Reflectance of Horizontal and Low-Sloped Surfaces in the Field,
approved August 15, 2006 (``ASTM E1918''); IBR approved for Sec.
86.1869-12(b).
(b) American National Standards Institute (ANSI). American National
Standards Institute, 25 W 43rd Street, 4th Floor, New York, NY 10036;
(212) 642-4900; www.ansi.org.
(1) CSA/ANSI NGV1:22, Compressed Natural Gas Vehicle (NGV) Fuelling
Connection Devices, Fourth edition, published December 2022; IBR
approved for Sec. 86.1813-17(f).
(2) [Reserved]
* * * * *
0
3. Amend Sec. 86.010-18 by adding paragraph (n)(4) to read as follows:
Sec. 86.010-18 On-board Diagnostics for engines used in applications
greater than 14,000 pounds GVWR.
* * * * *
(n) * * *
(4) For model year 2027 and later engines meeting the requirements
of this section under 40 CFR 1036.150(k) or 1071.80, manufacturers may
continue to use approved deficiencies through model year 2029.
* * * * *
Subpart L--[Removed and Reserved]
0
4. Remove and reserve subpart L, consisting of Sec. Sec. 86.1101-87
through 86.1117.
0
5. Amend Sec. 86.1810-17 by adding paragraph (l) to read as follows:
Sec. 86.1810-17 General requirements.
* * * * *
(l) Diesel-fueled vehicles must meet SCR-related design and
maintenance provisions as specified in 40 CFR 1036.111 and 1036.115(i)
starting no later than model year 2029.
0
6. Amend Sec. 86.1813-17 by revising paragraph (f)(1) to read as
follows:
Sec. 86.1813-17 Evaporative and refueling emission standards.
* * * * *
(f) * * *
(1) Compressed natural gas vehicles must meet the requirements for
fueling connection devices as specified in CSA/ANSI NGV 1:22
(incorporated by reference, see Sec. 86.1).
* * * * *
0
7. Amend Sec. 86.1844-01 by adding paragraph (d)(22) to read as
follows:
Sec. 86.1844-01 Information requirements: Application for
certification and submittal of information upon request.
* * * * *
(d) * * *
(22) For vehicles using SCR, describe the following design
features:
(i) Audible and visual signals required under Sec. 1039.111(c).
(ii) Compensation algorithms required under Sec. 1039.115(h)(2).
* * * * *
PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVY-DUTY
HIGHWAY ENGINES
0
8. The authority citation for part 1036 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
9. Amend Sec. 1036.15 by revising paragraph (d)(6) to read as follows:
Sec. 1036.15 Other applicable regulations.
* * * * *
(d) * * *
(6) Defect reporting and recall.
* * * * *
0
10. Amend Sec. 1036.101 by revising paragraph (b) to read as follows:
Sec. 1036.101 Overview of exhaust emission standards.
* * * * *
(b) You may optionally test hybrid powertrains, rather than testing
the engine alone, but only if you use powertrain testing to demonstrate
compliance with all requirements in this part 1036. Except as
specified, provisions of this part that reference engines apply equally
to hybrid powertrains.
0
11. Amend Sec. 1036.104 by revising paragraphs (a)(3), (b), (c)(1),
and (e) to read as follows:
Sec. 1036.104 Criteria pollutant emission standards--NOX,
HC, PM, and CO.
* * * * *
(a) * * *
(3) The following off-cycle emission standards apply for Light HDE,
Medium HDE, and Heavy HDE using the procedures specified in Sec.
1036.530, as follows:
Table 3 to Paragraph (a)(3) of Sec. 1036.104--Compression-Ignition Standards for Off-Cycle Testing
----------------------------------------------------------------------------------------------------------------
Temperature-
based HC mg/ PM mg/ CO g/
Off-cycle bin NOX adjustment for hp[middot]hr hp[middot]hr hp[middot]hr
NOX a
----------------------------------------------------------------------------------------------------------------
Bin 1........................ 10.0 g/hr....... (25.0-Tamb) .............. .............. ..............
.0.25.
Bin 2........................ 58 mg/ (25.0-Tamb) 120 7.5 9
hphr. .2.2.
----------------------------------------------------------------------------------------------------------------
\a \ Tambis the mean ambient temperature, in [deg]C, over a shift-day, or equivalent. Adjust the off-cycle NOX
standard for Tamb below 25.0 [deg]C by adding the calculated temperature adjustment to the specified NOX
standard (in g/hr for Bin 1 and mg/hp. [middot] hr for Bin 2). Round the temperature adjustment to the same
precision as the NOX standard for the appropriate bin. If you declare a NOX FEL for the engine family, do not
apply the FEL scaling calculation from paragraph (c)(3) of this section to the calculated temperature
adjustment.
(b) Clean Idle. You may optionally certify compression-ignition
engines to the Clean Idle NOX emission standard using the
Clean Idle test specified in Sec. 1036.525. The optional Clean Idle
NOX emission standard is 30.0 g/hr for model years 2024
through 2026, and 10.0 g/hr for model year 2027 and later. The standard
applies separately to each mode of the Clean Idle test. If you certify
an engine family to the Clean Idle standards, it is subject to all
these voluntary standards as if they were mandatory.
(c) * * *
(1) To generate or use emission credits, you must specify a family
emission limit for each engine family. Declare the family emission
limit corresponding to useful life for engine operation over the FTP
duty cycle, FELFTP, expressed to the same number of decimal
places as the emission standard. Use FELFTP to calculate
emission credits in subpart H of this part.
* * * * *
(e) Useful life. The exhaust emission standards of this section
apply for the useful life, expressed in vehicle miles, or hours of
engine operation, or years in service, whichever comes first, as
follows:
[[Page 43227]]
Table 4 to Paragraph (e) of Sec. 1036.104--Useful life by Primary Intended Service Class
----------------------------------------------------------------------------------------------------------------
Model year 2029 and earlier Model year 2030 and later
Primary intended service class -----------------------------------------------------------------------
Miles Years Hours Miles Years Hours
----------------------------------------------------------------------------------------------------------------
Spark-ignition HDE...................... 110,000 10 .......... 200,000 15 10,000
Light HDE............................... 110,000 10 .......... 270,000 15 13,000
Medium HDE.............................. 185,000 10 .......... 350,000 12 17,000
Heavy HDE............................... 435,000 10 22,000 650,000 11 32,000
----------------------------------------------------------------------------------------------------------------
* * * * *
0
12. Amend Sec. 1036.110 by:
0
a. Revising paragraph (b)(8);
0
b. Removing and reserving paragraph (b)(10);
0
c. Revising paragraph (b)(11)(i);
0
d. Adding paragraphs (b)(19) through (b)(27); and
0
e. Revising paragraph (c).
The revisions and additions read as follows:
Sec. 1036.110 Diagnostic controls.
* * * * *
(b) * * *
(8) Include the additional data-stream signals in 13 CCR
1971.1(h)(4.2.3)(E), (F), and (G) as freeze-frame conditions in the
same manner as requirements for signals identified in 13 CCR
1971.1(h)(4.3).
* * * * *
(11) * * *
(i) You must submit additional information as needed to demonstrate
that you meet the requirements of this section that are not covered by
the California Executive order. For example, you may demonstrate
compliance with the data-stream parameter requirements in paragraph
(b)(9) of this section and the in-cab display requirements in paragraph
(c) of this section by attesting that you meet those requirements.
* * * * *
(19) For the requirements in 13 CCR 1971.1(d), an in-use minimum
performance ratio of 0.100 applies for all monitors.
(20) The comprehensive component monitoring requirements in 13 CCR
1971.1(g)(3.1) for directly or indirectly monitoring inputs related to
inducement strategies do not apply.
(21) Meet the aging and data collection requirements in 13 CCR
1971.1(i)(2.3.4) using the procedures described in 40 CFR 1036.245.
(22) Use the definition of Federal Test Procedure cycle as defined
in 40 CFR 1036.512, and the Supplemental Emission Test as defined in 40
CFR 1036.510 in lieu of the procedures defined in 1971.1(c).
(23) For OBD systems that have NOx converting catalyst systems with
more than one catalyst in series, the manufacturer may increment the
denominator for a monitor required by section (e)(6) using the criteria
set forth in section 1971.1(d)(4.3.2)(G).
(24) For engines with catalyzed PM filters:
(i) The criterion for exempting catalyzed PM filters from
monitoring based on an NMHC conversion capability is increasing
emissions by 30% or more of the applicable standard, rather than 15% as
specified in 13 CCR 1971.1(e)(8.2.4)(A)(iii).
(ii) The feedgas generation requirements in 13 CCR
1971.1(e)(8.2.4)(B) do not apply.
(iii) The NMHC conversion requirements in 13 CCR
1971.1(e)(8.2.4)(A) do not apply if you instead comply with the
catalyzed PM filter integrity requirements 13 CCR 1971.1(e)(8.2.1).
(25) OBD systems that have an NMHC catalyst conversion efficiency
monitor that meets 13 CCR 1971.1(e)(5.2.2) do not need to meet the
feedgas generation performance monitoring requirements of sections 13
CCR 1971.1(e)(5.2.3)(B).
(26) For monitors that increment denominators using any of the
criteria in 13 CCR 1971.1(d)(4.3.2), the readiness status of that
monitor may be considered to have ``fully executed and determined that
the component or system is not malfunctioning'' if at least 15 warm-up
cycles and 400 minutes of engine run time have occurred since the fault
memory last cleared, and no permanent fault code is stored for that
monitor.
(27) The OBD requirements in this section do not apply for hybrid
components, unless you use powertrain testing to demonstrate compliance
with the requirements of this part 1036.
(c) Design the system to display the following information in the
cab:
(1) For inducement triggering conditions under Sec. 1036.111,
identify whether the condition relates to DEF level, DEF quality, or
tampering. The following additional requirements apply for those
inducements and any other AECD related to the SCR or DPF system that
derates engine output and changes the status of an aftertreatment
system (for example, hydrocarbon or DEF dosing is disabled):
(i) Identify whether the fault condition is related to SCR or DPF
system.
(ii) Indicate the fault code for the detected problem, a
description of the fault code, and the current speed restriction, as
applicable.
(iii) If there are additional derate stages, also indicate the next
speed restriction and the time remaining until starting the next
restriction. If the derate involves something other than restricting
vehicle speed, such as a torque derate, adjust the information to
correctly identify any current and pending restrictions.
(2) Identify on demand the total number of active and completed
diesel particulate filter regeneration events that have taken place
since installing the current particulate filter.
(3) Identify on demand the lifetime and current rate of DEF
consumption, such as gallons of DEF consumed per mile or gallons of DEF
consumed per gallon of diesel fuel consumed. Design the system to allow
the operator to reset the current rate of DEF consumption.
(4) Manufactures can use discretion to decide what to safely
display while the vehicle is in-motion, which may be a more limited set
of the required information than is displayed when the vehicle is
stationary.
* * * * *
0
13. Revise Sec. 1036.111 to read as follows:
Sec. 1036.111 Inducements related to SCR.
Engines using SCR to control emissions depend on a constant supply
of diesel exhaust fluid (DEF). This section describes how manufacturers
must design their engines to induce operators to take appropriate
actions to ensure the SCR system has quality DEF. The requirements of
this section apply equally for engines installed in heavy-duty vehicles
at or below 14,000 lbs GVWR. The requirements of this section apply
starting in model year 2027, though you may comply with the
requirements of this section in earlier model years. Transitional
provisions apply for model years 2027 and 2028 as
[[Page 43228]]
described in paragraph (f) of this section.
(a) [Reserved]
(b) Inducement triggering conditions. Create strategies that
monitor for and trigger an inducement signal based on the following
conditions:
(1) DEF supply falling to 2.5 percent of DEF tank capacity or a
level corresponding to three hours of engine operation, based on
available information on DEF consumption rates.
(2) DEF with a urea concentration below 20 mass percent. You may
determine urea concentration based on direct measurement or based on a
surrogate value such as exhaust NOX concentration before and
after an SCR catalyst. Measurement may be limited to one time for each
occurrence of adding to the DEF tank. Use good engineering judgment to
determine urea concentration as soon as possible.
(3) Any signal indicating that a catalyst is missing.
(4) Open circuit faults related to the following: DEF tank level
sensor, DEF pump, DEF quality sensor, SCR wiring harness,
NOX sensors, DEF dosing valve, DEF tank heater, DEF tank
temperature sensor, and aftertreatment control module.
(c) Audible signals. Design engines with audible signals
corresponding to the inducement triggering conditions in paragraph (b)
of this section, subject to our approval, as follows:
(1) Audible signals must be sufficient to alert the operator to the
need for service. The tone must be active for 90 seconds with repeated
tones on one of the following schedules:
(i) For DEF supply, the tone must occur when the system detects the
triggering condition in paragraph (b)(1) of this section, when the
engine detects an empty DEF tank, 30 minutes after detecting an empty
DEF tank, 60 minutes after detecting an empty DEF tank, and then every
60 minutes until key-off. Reevaluate at each key-on cycle.
(ii) For all conditions other than DEF supply, the tone must occur
when the system detects a triggering condition in paragraph (b)(2)
through (4) of this section, 30 minutes after detecting the triggering
condition, 90 minutes after detecting the triggering condition, and
then every 180 minutes until key-off. Reevaluate at each key-on cycle.
(2) You may design your engines to suspend the audible signals in
paragraph (c)(1) of this section when ambient temperature is below -11
[deg]C. If the triggering condition persists, restart audible signals
at the same point in the schedule identified in paragraph (c)(1) of
this section when ambient temperature is above 0 [deg]C. Reevaluate at
each key-on cycle.
(d) Speed derates. You may rely on derating engine performance for
protecting aftertreatment systems and other engine components from
catastrophic damage, as long as derating is not based only on an
assessment of emission control performance (such as evaluation of
catalyst conversion efficiency).
(e) Deactivating inducements. Program the engine to deactivate
inducements as follows:
(1) Evaluate whether the detected inducement triggering condition
continues to apply. Deactivate inducements if the engine confirms that
the detected inducement triggering condition is resolved.
(2) Allow a generic scan tool to deactivate inducement triggering
codes.
(f) Transition provisions. The following provisions apply through
model year 2028 for engines that do not meet requirements for audible
signals as described in paragraph (c) of this section:
(1) The following terms and general provisions apply under this
paragraph (f):
(i) As described in Sec. 1036.110, this section relies on terms
and requirements specified for OBD systems by California ARB in 13 CCR
1968.2 and 1971.1 (incorporated by reference, see Sec. 1036.810).
(ii) The provisions of this section apply differently based on an
individual vehicle's speed history. A vehicle's speed category is based
on the OBD system's recorded value for average speed for the preceding
30 hours of non-idle engine operation. The vehicle speed category
applies at the point that the engine first detects an inducement
triggering condition identified under paragraph (b) of this section and
continues to apply until the inducement triggering condition is fully
resolved as specified in paragraph (e) of this section. Non-idle engine
operation includes all operating conditions except those that qualify
as idle based on OBD system controls as specified in 13 CCR
1971.1(h)(5.4.10). Apply speed derates based on the following
categories:
Table 1 to Paragraph (f)(1)(ii) of Sec. 1036.111--Vehicle Categories
------------------------------------------------------------------------
Vehicle category \a\ Average speed (mi/hr)
------------------------------------------------------------------------
Low-speed................................. speed <= 15.
Medium-speed.............................. 15 <= speed <= 25.
High-speed................................ speed >= 25.
------------------------------------------------------------------------
\a\ A vehicle is presumed to be a high-speed vehicle if it has not yet
logged 30 hours of non-idle operation.
(iii) Where engines derate power output as specified in this
section, the derate must decrease vehicle speed by 1 mi/hr for every
five minutes of engine operation until reaching the specified derate
speed. This paragraph (a)(3) applies at the onset of an inducement, at
any transition to a different step of inducement, and for any derate
that recurs under paragraph (e)(3) of this section.
(2) The provisions of this paragraph (f) apply differently based on
an individual vehicle's speed history. A vehicle's speed category is
based on the average speed for the preceding 30 hours of non-idle
engine operation. The vehicle speed category applies at the point that
the engine first detects an inducement triggering condition identified
under paragraph (b) of this section and continues to apply until the
inducement triggering condition is fully resolved as specified in
paragraph (e) of this section. Non-idle engine operation includes all
operating conditions except those that qualify as idle based on OBD
system controls as specified in 13 CCR 1971.1(h)(5.4.10). Apply speed
derates based on the following categories:
Table 2 to Paragraph (f)(2) of Sec. 1036.111--Vehicle Categories
------------------------------------------------------------------------
Vehicle category \a\ Average speed (mi/hr)
------------------------------------------------------------------------
Low-speed................................. speed < 15.
Medium-speed.............................. 15 <= speed < 25.
High-speed................................ speed >= 25.
------------------------------------------------------------------------
\a\ A vehicle is presumed to be a high-speed vehicle if it has not yet
logged 30 hours of non-idle operation.
(3) Where engines derate power output as specified in this
paragraph (f), the derate must decrease vehicle speed by 1 mi/hr for
every five minutes of engine operation until reaching the specified
derate speed. This paragraph (f)(3) applies at the onset of an
inducement, at any transition to a different step of inducement, and
for any derate that recurs under paragraph (f)(6) of this section.
(4) You may derate based on the following inducement triggering
conditions instead of the conditions specified in paragraph (b) of this
section:
(i) DEF supply falling to 2.5 percent of DEF tank capacity or a
level corresponding to three hours of engine operation, based on
available information on DEF consumption rates.
(ii) DEF quality failing to meet your concentration specifications.
(5) Engines must follow the derate schedule described in this
paragraph (f)(4) if the engine detects an
[[Page 43229]]
inducement triggering condition identified in paragraph (b) of this
section. The derate takes the form of a maximum drive speed for the
vehicle. This maximum drive speed decreases over time based on hours of
non-idle engine operation without regard to engine starting.
(i) Apply speed-limiting derates according to the following
schedule:
Table 3 to Paragraph (f)(5)(i) of Sec. 1036.111--Derate Schedule for Detected Inducement Triggering Conditions
\a\
----------------------------------------------------------------------------------------------------------------
High-speed vehicles Medium-speed vehicles Low-speed vehicles
----------------------------------------------------------------------------------------------------------------
Hours of non- Hours of non-
Hours of non-idle engine Maximum speed idle engine Maximum speed idle engine Maximum speed
operation (mi/hr) operation (mi/hr) operation (mi/hr)
----------------------------------------------------------------------------------------------------------------
0............................... 65 0 55 0 45
6............................... 60 6 50 5 40
12.............................. 55 12 45 10 35
20.............................. 50 45 40 30 25
86.............................. 45 70 35 .............. ..............
119............................. 40 90 25 .............. ..............
144............................. 35 .............. .............. .............. ..............
164............................. 25 .............. .............. .............. ..............
----------------------------------------------------------------------------------------------------------------
\a\ Hours start counting when the engine detects an inducement triggering condition specified in paragraph (b)
of this section. For DEF supply, you may program the engine to reset the timer to three hours when the engine
detects an empty DEF tank.
(ii) You may design and produce engines that will be installed in
motorcoaches with an alternative derate schedule that starts with a 65
mi/hr derate when an inducement triggering condition is first detected,
steps down to 50 mi/hr after 80 hours, and concludes with a final
derate speed of 25 mi/hr after 180 hours of non-idle operation.
(6) Treat any detected inducement triggering condition that recurs
within 40 hours of engine operation as the same detected inducement
triggering condition, which would restart the derate at the same point
in the derate schedule that the system last deactivated the derate.
0
14. Amend Sec. 1036.115 by revising paragraphs (a) introductory text,
(f)(3), and (i) to read as follows:
Sec. 1036.115 Other requirements.
(a) Crankcase emissions. Engines may not discharge crankcase
emissions into the ambient atmosphere throughout the useful life, other
than those that are routed to the exhaust upstream of exhaust
aftertreatment during all operation, except as follows:
* * * * *
(f) * * *
(3) DEF supply and DEF quality are adjustable parameters. The
practically adjustable range includes any amount of DEF for which the
engine's diagnostic system does not trigger inducement provisions under
Sec. 1036.111.
* * * * *
(i) SCR-related requirements. The following additional requirements
apply for engines with SCR:
(1) Diesel exhaust fluid tanks must be sized to require refilling
no more frequently than the vehicle operator will need to refill the
fuel tank, even for worst-case assumptions related to fuel efficiency
and refueling volumes.
(2) Design engines to respond to varying DEF quality with
compensation algorithms that varies DEF injection to maintain
NOX emission control that is comparable to operation with
DEF conforming to the specifications referenced in the definition of
``diesel exhaust fluid'' in Sec. 1036.801, subject to the limitations
of the emission control hardware.
(3) Design engines for DEF freeze protection by including a warming
system to thaw DEF to restore DEF flow into the exhaust system within
70 minutes after engine starting using the procedure described in Sec.
1036.560.
* * * * *
0
15. Amend Sec. 1036.120 by revising paragraph (b) to read as follows:
Sec. 1036.120 Emission-related warranty requirements.
* * * * *
(b) Warranty period. Your emission-related warranty must be valid
for at least as long as the minimum warranty periods listed in this
paragraph (b) in vehicle miles, or hours of engine operation, or years
in service, whichever comes first. You may offer an emission-related
warranty more generous than we require. The emission-related warranty
for the engine may not be shorter than any published warranty you offer
without charge for the engine. Similarly, the emission-related warranty
for any component may not be shorter than any published warranty you
offer without charge for that component. If an extended warranty
requires owners to pay for a portion of repairs, those terms apply in
the same manner to the emission-related warranty. The warranty period
begins when the vehicle is placed into service. The following minimum
warranty periods apply:
Table 1 to Paragraph (b) of Sec. 1036.120--Warranty by Primary
Intended Service Class
------------------------------------------------------------------------
Primary intended service
class Mileage Years
------------------------------------------------------------------------
Spark-Ignition HDE.......... 50,000 5
Light HDE................... 50,000 5
Medium HDE.................. 100,000 5
Heavy HDE................... 100,000 5
------------------------------------------------------------------------
[[Page 43230]]
* * * * *
0
16. Amend Sec. 1036.125 by revising the introductory text and
paragraphs (a)(2), (g) introductory text, and (h)(8) to read as
follows:
Sec. 1036.125 Maintenance instructions and allowable maintenance.
Give the ultimate purchaser of each new engine written instructions
for maintaining and using the engine. As described in paragraph (h) of
this section, these instructions must identify how owners properly
maintain and use engines to clarify responsibilities for regulatory
requirements such as emission-related warranty and defect reporting.
Maintenance includes any inspection, adjustment, cleaning, repair, or
replacement of components and is classified as either emission-related
or not emission-related and each of these can be classified as either
scheduled or unscheduled. Further, some emission-related maintenance is
also classified as critical emission-related maintenance.
(a) * * *
(2) Minimum scheduled maintenance intervals. You may not schedule
critical emission-related maintenance more frequently than the minimum
intervals specified or allowed in this paragraph (a), except as
specified in paragraph (g) of this section. The minimum intervals
specified for each component applies to actuators, sensors, tubing,
valves, and wiring associated with that component, except as specified.
Table 1 to Paragraph (a)(2) of Sec. 1036.125--Minimum Scheduled Maintenance Intervals for Replacement in Miles
(or Hours)
----------------------------------------------------------------------------------------------------------------
Spark-ignition
Components HDE Light HDE Medium HDE Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs......................... 25,000 (750) ................. ................. .................
DEF filters......................... ................. 100,000 (3,000) 100,000 (3,000) 100,000 (3,000)
Crankcase ventilation valves and 60,000 (1,800) 60,000 (1,800) 60,000 (1,800) 60,000 (1,800)
filters............................
Ignition wires and coils............ 50,000 (1,500) ................. ................. .................
Oxygen sensors...................... 80,000 (2,400) ................. ................. .................
Air injection system components..... 110,000 (3,300) ................. ................. .................
Sensors, actuators, and related 100,000 (3,000) 100,000 (3,000) 150,000 (4,500) 150,000 (4,500)
control modules that are not
integrated into other systems......
Particulate filtration systems 100,000 (3,000) 100,000 (3,000) 250,000 (7,500) 250,000 (7,500)
(other than filter substrates).....
Catalyst systems (other than 110,000 (3,300) 110,000 (3,300) 185,000 (5,550) 435,000 (13,050)
catalyst substrates), fuel
injectors, electronic control
modules, hybrid system components,
turbochargers, and EGR system
components (including filters and
coolers)...........................
Catalyst substrates and particulate 110,000 (3,300) 110,000 (3,300) 185,000 (5,550) 435,000 (13,050)
filter substrates in model year
2029 and earlier...................
Catalyst substrates and particulate 200,000 (10,000) 270,000 (13,000) 350,000 (17,000) 650,000 (32,000)
filter substrates in model year
2030 and later.....................
----------------------------------------------------------------------------------------------------------------
Table 2 to Paragraph (a)(2) of Sec. 1036.125--Minimum Scheduled Maintenance Intervals for Adjustment or
Cleaning
----------------------------------------------------------------------------------------------------------------
Accumulated miles (hours) for components
-------------------------------------------------------------------------------
Component Spark-ignition
HDE Light HDE Medium HDE Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs..................... 25,000 (750) ................. ................... ...................
EGR-related filters and coolers, 50,000 (1,500) 50,000 (1,500) 50,000 (1,500)..... 50,000 (1,500).
fuel injectors, and crankcase
ventilation valves and filters.
DEF filters..................... ................. 50,000 (1,500) 50,000 (1,500)..... 50,000 (1,500).
Ignition wires and coils........ 50,000 (1,500) ................. ................... ...................
Oxygen sensors.................. 80,000 (2,400) ................. ................... ...................
Air injection system components. 100,000 (3,000) ................. ................... ...................
Catalyst system components, EGR 100,000 (3,000) 100,000 (3,000) 100,000 (3,000), 100,000 (3,000),
system components (other than then 150,000 then 150,000
filters or coolers), (4,500). (4,500).
particulate filtration system
components, and turbochargers.
----------------------------------------------------------------------------------------------------------------
* * * * *
(g) Payment for scheduled maintenance. Owners are responsible for
properly maintaining their engines; this generally includes paying for
scheduled maintenance, even within the warranty period. However, you
may commit to paying for scheduled maintenance as described in
paragraph (a)(1)(iv) of this section to demonstrate that the
maintenance will occur. You may also schedule maintenance not otherwise
allowed by paragraph (a)(2) of this section if you pay for it. You must
pay for scheduled maintenance on any component during the useful life
if it meets all the following conditions:
* * * * *
(h) * * *
(8) Include a troubleshooting guide to address the following
signals related to SCR inducement:
(i) The schedule for visual and audible signals (including
indication that the signal will begin prior to the DEF tank being
completely empty).
(ii) The meaning of any trouble lights that indicate specific
problems (e.g., DEF level).
(iii) A description of the three types of SCR-related triggers that
cause the visual and audible signals (DEF level, DEF quality and
tampering) and that further information on the inducement
[[Page 43231]]
cause (e.g., trouble codes) is available using the OBD system.
* * * * *
0
17. Amend Sec. 1036.130 by:
0
a. Revising paragraph (b)(7)(ii);
0
b. Adding paragraph (b)(10); and
0
c. Revising paragraph (c).
The revisions and addition read as follows:
Sec. 1036.130 Installation instructions for vehicle manufacturers.
* * * * *
(b) * * *
(7) * * *
(ii) Describe how vehicle manufacturers must install diesel exhaust
fluid tanks with sensors and equipment as needed to meet the
requirements of Sec. Sec. 1036.110, 1036.111, and 1036.115(i).
* * * * *
(10) For powertrain families, describe any limitations on the type
or configuration of vehicles.
(c) Give the vehicle manufacturer engine data and information to
support vehicle certification as described in Sec. 1036.505.
* * * * *
0
18. Amend Sec. 1036.135 by revising paragraph (e) to read as follows:
Sec. 1036.135 Labeling.
* * * * *
(e) You may ask us to approve modified labeling requirements in
this part if you show that it is necessary or appropriate. We will
approve your request if your alternative label is consistent with the
requirements of this part. We may also specify modified labeling
requirements to be consistent with the intent of 40 CFR part 1037.
* * * * *
0
19. Amend Sec. 1036.150 by:
0
a. Revising paragraphs (k) and (z) introductory text; and
0
b. Adding paragraphs (aa), (bb), and (cc).
The revisions and additions read as follows:
Sec. 1036.150 Interim provisions.
* * * * *
(k) Limited production volume allowance. You may produce a limited
number of Heavy HDE in model years 2027 through 2029 that continue to
meet the criteria pollutant standards as they applied under 40 CFR
86.007-11. The maximum number of engines you may produce under this
limited production allowance is 5 percent of the annual average of your
actual production volume of Heavy HDE in model years 2023-2025. Engine
certification under this paragraph (k) is subject to the following
conditions and requirements:
(1) Engines must meet all the standards and other requirements that
apply under 40 CFR part 86 for model year 2026. Engines must be
certified in separate engine families that qualify for carryover
certification as described in Sec. 1036.235(d).
(2) [Reserved].
(3) Include the following compliance statement instead of the
compliance statement in Sec. 1036.135(c)(8): ``THIS ENGINE COMPLIES
WITH U.S. EPA REGULATIONS FOR [MODEL YEAR] HEAVY-DUTY HIGHWAY ENGINES,
EXCEPT THAT IT CONFORMS TO CERTAIN MODEL YEAR 2026 STANDARDS UNDER 40
CFR 1036.150(k).''
* * * * *
(z) Alternative family pass criteria for in-use testing. The
following family pass criteria apply for manufacturer-run in-use
testing instead of the pass criteria described in Sec. 1036.425 for
model years 2027 and 2028:
* * * * *
(aa) Carryover deterioration factors. You may certify an engine
family to compression-ignition standards using carryover data with a
deterioration factor based on vehicle speeds of either 40.26 mi/hr for
test sequence 1 or 44.48 mi/hr for test sequence 2 under Sec.
1036.245.
(bb) OBD provisions for NCP engines. If you certify a model year
2027 or later engine family under 40 CFR part 86, subpart A, as
described in 40 CFR 1071.60, do not count those engine families when
determining testing requirements that apply under Sec. 1036.110.
(cc) Deterioration factors through model year 2029. Through model
year 2029, determine deterioration factors based on estimated emission
levels corresponding to the useful life that applies for the engine
family. This may involve interpolation if you measured emission levels
after service accumulation exceeding the useful life (in miles).
0
20. Amend Sec. 1036.201 by revising paragraph (h) to read as follows:
Sec. 1036.201 General requirements for obtaining a certificate of
conformity.
* * * * *
(h) For engines that become new after being placed into service,
such as rebuilt engines installed in new vehicles, we may specify
alternative certification provisions consistent with the intent of this
part. See 40 CFR 1068.120(h) and the definition of ``new motor vehicle
engine'' in Sec. 1036.801.
0
21. Amend Sec. 1036.205 by:
0
a. Adding paragraph (b)(12); and
0
b. Revising paragraphs (c), (e), and (r)(1).
The addition and revisions read as follows:
Sec. 1036.205 Requirements for an application for certification.
* * * * *
(b) * * *
(12) Describe the following SCR-related design features:
(i) Audible signals required under Sec. 1036.111(c).
(ii) Compensation algorithms required under Sec. 1036.115(i)(2).
(c) Explain in detail how the engine diagnostic system works,
describing especially the engine conditions (with the corresponding
diagnostic trouble codes) that cause the malfunction indicator to go
on. Also describe any approved conditions under which the diagnostic
system disregards trouble codes as specified in Sec. 1036.110(b)(12)
and any exceptions from comprehensive component monitoring as allowed
under Sec. 1036.110(b)(20).
* * * * *
(e) Describe any test equipment and procedures that you used,
including any special or alternative test procedures you used (see
Sec. 1036.501).
* * * * *
(r) * * *
(1) For physically adjustable operating parameters, include the
nominal or recommended setting, the intended practically adjustable
range, and the limits or stops used to establish adjustable ranges.
State that the limits, stops, or other means of inhibiting adjustment
are effective in preventing adjustment of parameters on in-use engines
to settings outside your intended practically adjustable ranges and
provide information to support this statement.
* * * * *
0
22. Amend Sec. 1036.230 by revising paragraph (f)(3) to read as
follows:
Sec. 1036.230 Selecting engine families.
* * * * *
(f) * * *
(3) If you certify both engine fuel maps and powertrain fuel maps
for an engine family, you may split the engine family into two separate
subfamilies. Indicate this in your application for certification, and
identify whether one or both of these sets of fuel maps applies for
each group of engines. If you do not split your family, all engines
within the family must conform to the engine fuel maps, including any
engines for which the powertrain maps also apply.
* * * * *
[[Page 43232]]
0
23. Amend Sec. 1036.235 by revising paragraphs (b) introductory text,
(e), and (f) to read as follows:
Sec. 1036.235 Testing requirements for certification.
* * * * *
(b) Test your emission-data engines using the procedures and
equipment specified in subpart F of this part. In the case of dual-fuel
engines, measure emissions when operating with each type of fuel for
which you intend to certify the engine. In the case of flexible-fuel
engines, measure emissions when operating with the fuel mixture that
best represents in-use operation or is most likely to have the highest
NOX emissions (or NOX + NMHC emissions for
engines subject to NOX + NMHC standards), though you may ask
us instead to perform tests with both fuels separately if you can show
that intermediate mixtures are not likely to occur in use.
* * * * *
(e) We may require you to test a second engine of the same
configuration in addition to the engines tested under paragraph (b) of
this section.
(f) If you use an alternative test procedure under 40 CFR 1065.10
and later testing shows that such testing does not produce results that
are equivalent to the procedures specified in subpart F of this part,
we may reject data you generated using the alternative procedure.
* * * * *
0
24. Amend Sec. 1036.240 by revising paragraphs (b) and (c)
introductory text to read as follows:
Sec. 1036.240 Demonstrating compliance with criteria pollutant
emission standards.
* * * * *
(b) Your engine family is deemed not to comply if any emission-data
engine representing that family has test results showing an official
emission result or a deteriorated emission level for any pollutant that
is above an applicable duty-cycle emission standard (including all
corrections and adjustments). Similarly, your engine family is deemed
not to comply if any emission-data engine representing that family has
test results showing any emission level above the applicable off-cycle
emission standard for any pollutant. This also applies for all test
points for emission-data engines within the family used to establish
deterioration factors.
(c) To compare emission levels from the emission-data engine with
the applicable duty-cycle emission standards, apply deterioration
factors to the measured emission levels for each pollutant. Section
1036.245 specifies how to test engines and engine components to develop
deterioration factors that represent the deterioration expected in
emissions over your engines' useful life. Section 1036.246 describes
how to confirm or modify deterioration factors based on in-use
verification testing. Your deterioration factors must take into account
any available data from other in-use testing with similar engines.
Small manufacturers may use assigned deterioration factors that we
establish. Other manufacturers may request to certify engine families
using assigned deterioration factors that we establish. The assigned
deterioration factors may apply for a projected nationwide production
volume up to 10,000 engines, including all affiliated companies. The
deterioration factors apply to entire engine families. Apply
deterioration factors as follows:
* * * * *
0
25. Amend Sec. 1036.245 by revising paragraph (c) to read as follows:
Sec. 1036.245 Deterioration factors for exhaust emission standards.
* * * * *
(c) If you are unable to determine deterioration factors for an
engine family under paragraph (a) of this section, select engines,
subsystems, or components for testing. Determine deterioration factors
based on service accumulation and related testing to represent the
deterioration expected from in-use engines over the useful life,
including effects of crankcase emissions and infrequent regeneration.
You may perform maintenance on emission-data engines as described in
Sec. 1036.125 and 40 CFR part 1065, subpart E. Use good engineering
judgment for all aspects of the effort to establish deterioration
factors under this paragraph (c). Send us your test plan for our
preliminary approval under Sec. 1036.210. You may apply deterioration
factors based on testing under this paragraph (c) to multiple engine
families, consistent with the provisions in paragraph (a) of this
section. Engine dynamometer hours accumulated during emission
measurements do not count toward meeting the minimum number of engine
dynamometer hours in paragraph (c)(3) of this section or the total
service accumulation hours in paragraph (c)(8) of this section.
Determine deterioration factors based on a combination of minimum
required engine dynamometer aging hours and accelerated bench-aged
aftertreatment as follows:
(1) Select an emission-data engine and aftertreatment devices and
systems that can be assembled into a certified configuration to
represent the engine family. Stabilize the engine and aftertreatment
devices and systems, together or separately, to prepare for emission
measurements. These stabilization hours count toward meeting the
minimum number of engine dynamometer hours in paragraph (c)(3) of this
section.
(2) Perform low-hour emission measurement once the engine has
operated with aftertreatment long enough to stabilize the emission
control. Measure emissions of all regulated pollutants while the engine
operates over all applicable duty cycles on an engine dynamometer as
described in subpart F of this part. You may use the average of
multiple emission tests to determine your emissions value for the
purpose of calculating a deterioration factor.
(3) Perform additional service accumulation as described in
paragraph (c)(3) of this section on an engine dynamometer until you
reach the minimum specified number of engine dynamometer hours:
Table 1 to Paragraph (c)(3) of Sec. 1036.245--Minimum Required Engine
Dynamometer Aging Hours by Primary Intended Service Class
------------------------------------------------------------------------
Minimum engine dynamometer
Primary intended service class hours
------------------------------------------------------------------------
Spark-ignition HDE........................ 300
Light HDE................................. 1,250
Medium HDE................................ 1,500
Heavy HDE................................. 1,500
------------------------------------------------------------------------
[[Page 43233]]
(4) Perform service accumulation in the laboratory by operating the
engine or hybrid powertrain on a dynamometer repeatedly over one of the
test sequences in paragraph (c)(4)(i) or (ii) of this section, or use a
different test sequence (and cycle validation) that we approve in
advance. For spark-ignition engines, you may exclude operation over the
LLC in paragraphs (c)(4)(i)(C) and (ii)(C) of this section. If you
conduct service accumulation for hybrid powertrains using an engine-
based simulation of powertrain testing as specified in 40 CFR 1037.551,
you may omit the hybrid components.
(i) Test sequence 1 is based on operating over the FTP, RMC, and
LLC. Operate the engine or hybrid powertrain as follows for test
sequence 1:
(A) Operate at idle for 2 hours.
(B) Operate for 105 1 hours over a repeat sequence of
one FTP followed by one RMC.
(C) Operate over one LLC.
(D) Operate at idle for 2 hours.
(E) Shut down the engine for cooldown to ambient temperature.
(F) Perform cycle validation for at least one FTP, one RMC, and one
LLC for the initial run through test sequence 1. If validation fails,
correct the problem and continue service accumulation. Use good
engineering judgment to ensure that the engine or hybrid powertrain
follows the test sequence throughout the duration of service
accumulation, for example by using real-time monitors.
(ii) Test sequence 2 is based on operating over the LLC and the
vehicle-based duty cycles from 40 CFR part 1037. Select the vehicle
subcategory and vehicle configuration from Sec. 1036.540 or Sec.
1036.545 with the highest reference cycle work for each vehicle-based
duty cycle. Operate the engine or hybrid powertrain as follows for test
sequence 2:
(A) Operate at idle for 2 hours.
(B) Operate for 105 1 hours over a repeat sequence of
one Heavy-duty Transient Test Cycle, then one 55 mi/hr highway cruise
cycle, and then one 65 mi/hr highway cruise cycle.
(C) Operate over one LLC.
(D) Operate at idle for 2 hours.
(E) Shut down the engine for cooldown to ambient temperature.
(F) Perform cycle validation for at least one heavy-duty transient
test cycle, one 55 mi/hr highway cruise cycle, one 65 mi/hr highway
cruise cycle, and one LLC for the initial run through test sequence 2.
If validation fails, correct the problem and continue service
accumulation. Use good engineering judgment to ensure that the engine
or hybrid powertrain follows the test sequence throughout the duration
of service accumulation, for example by using real-time monitors.
(5) If you use a nonmotoring dynamometer for service accumulation;
when running motoring points, set the dynamometer command to minimum
and use the operator demand to control speed.
(6) Use the following alternative cycle-validation criteria to
validate service accumulation.
Table 2 to Paragraph (c)(6) of Sec. 1036.245--Alternative Cycle Validation Criteria for Service Accumulation
\a\
----------------------------------------------------------------------------------------------------------------
Parameter Speed Torque Power
----------------------------------------------------------------------------------------------------------------
Slope, a1............................ ........... 0.800 <= a1 <= 1.030......... 0.800 <= a1 <= 1.030.
Absolute value of intercept, ........... <=6% of maximum mapped torque <=6% of maximum mapped power.
[verbar]a0[verbar].
Standard error of the estimate, SEE.. ........... ............................. <=15% of maximum mapped
power.
Coefficient of determination, r\2\... 0.95 >=0.650...................... >=0.650.
----------------------------------------------------------------------------------------------------------------
\a\ Cycle-validation criteria apply as described in 40 CFR 1065.514 unless otherwise specified.
(7) After performing the specified service accumulation on the
engine dynamometer, repeat the emission measurements described in
paragraph (c)(1) of this section.
(8) Calculate the total service accumulation representing hours of
engine operation over the useful life as follows:
(i) Use the following equation, except as specified in paragraph
(c)(8)(ii) of this section:
[GRAPHIC] [TIFF OMITTED] TP14JY26.027
Where:
UL = useful life mileage representing the longest useful life that
the deterioration factors would be used for.
k = 1.15 for Heavy HDE and 1.0 for all other primary intended
service classes.
vagingcycle = average speed of the vehicle, derived from
field data, based on the applications used for determining the
thermal exposure for the engine family as described in the field
data discussion in 40 CFR 1065.1131 or 40 CFR 1065.1147. If the
average speed from the field data is less than 20 mi/hr use 20 mi/hr
as the average speed.
Example for a model year 2030 Heavy HDE for test sequence 1:
UL = 650,000 miles
k = 1.15
vagingcycle = 40.26 mi/hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.028
ttotal = 18,567 hr
(ii) To determine deterioration factors for standards subject to a
shorter useful life, you may calculate a value for hours-of-service
accumulation corresponding to the shorter useful life using Eq.
1036.245-1. For example, this may apply if the testing will be used to
establish deterioration factors for a different primary intended
service class. Follow the procedure described in paragraph (c)(12) of
this section to determine deterioration factors for a shorter useful
life.
(9) Perform accelerated bench aging of aftertreatment devices to
finish service accumulation over the useful life, if the aftertreatment
was not aged to useful life in paragraph (c)(4) of this section.
(i) Calculate the bench aging hours by subtracting the actual
engine operating hours during service accumulation from ttotal and
dividing the difference by the acceleration factor determined in 40 CFR
1065.1139(a) for compression ignition engines and 40 CFR 1065.1149 for
spark ignition engines. Note that engine operating hours during service
accumulation is the sum of the engine stabilization hours under
paragraph (c)(1) of this section, service accumulation hours under
paragraph (c)(2) of this section, and engine stabilization hours under
paragraph (c)(11) of this section.
(ii) For powertrains where hybrid components are part of the
certified configuration, you may request a reduction in aging hours to
represent charge-sustaining engine operation, with our approval. You
may not account
[[Page 43234]]
for engine-off operation due to charge-depleting operation.
(iii) Use the accelerated bench-aging procedure in 40 CFR 1065.1131
through 1065.1145 for compression ignition engines, 40 CFR 1065.1147
through 1065.1155 for spark ignition engines, or get our advance
approval to use a different procedure that adequately accounts for
thermal and chemical degradation.
(10) After bench-aging aftertreatment devices, reinstall the
aftertreatment devices and systems on the engine used for service
accumulation in paragraph (c)(2) of this section, or install
aftertreatment devices and systems on a different emission-data engine
(or an equivalent engine) that has been stabilized without
aftertreatment as described in paragraph (c)(1) of this section. Ensure
that the aftertreatment is installed such that the engine is in a
certified configuration to represent the engine family.
(11) Operate the engine with the bench-aged aftertreatment devices
to allow controls to adapt to the aftertreatment condition and to
stabilize emission controls. For compression ignition engines, operate
at least 100 hours on an engine dynamometer as described in paragraph
(c)(4) of this section. You may omit the idle and cooldown periods in
paragraphs (c)(3)(i)(A), (D), and (E) or (c)(4)(ii)(A), (D), and (E) of
this section. For spark ignition engines use good engineering judgment
to determine the duty cycle and the operating time on an engine
dynamometer.
(12) Once stabilization is complete, repeat the emission
measurements described in paragraph (c)(1) of this section.
(13) Calculate each deterioration factor by comparing the highest
exhaust emissions at any point during aging where you measure emissions
and exhaust emissions at the low-hour test point as described in
paragraph (c)(1) of this section, without extrapolation.
(14) To determine separate deterioration factors corresponding to a
shorter useful life, calculate the total service accumulation
corresponding to the shorter useful life as described in paragraph
(c)(8)(ii) of this section. Once there is enough bench aging to
represent operation corresponding to the shorter useful life, perform
the steps described in paragraphs (c)(10) through (13) of this section,
including emission measurement of all relevant pollutants. After this
testing is complete, recalculate the required bench aging hours to
account for the additional operation on the engine dynamometer and
resume service accumulation to determine deterioration factors for the
longer useful life.
* * * * *
0
26. Amend Sec. 1036.255 by revising paragraphs (a), (c)(7), (d), and
(e) to read as follows:
Sec. 1036.255 EPA oversight on certificates of conformity.
(a) If we determine an application is complete and shows that the
engine family meets all the requirements of this part and the Clean Air
Act, we will issue a certificate of conformity for the engine family
for that model year. We may make the approval subject to additional
conditions.
* * * * *
(c) * * *
(7) Take any action that otherwise circumvents the intent of the
Clean Air Act or this part.
(d) We may void a certificate of conformity if you fail to keep
records, send reports, or give us information as required under this
part or the Clean Air Act. Note that these are also violations of 40
CFR 1068.101(a)(2).
(e) We may void a certificate of conformity if we find that you
intentionally submitted false or incomplete information. This includes
doing anything after submitting an application that causes submitted
information to be false or incomplete.
* * * * *
0
27. Amend Sec. 1036.410 by revising paragraph (c) to read as follows:
Sec. 1036.410 Selecting and screening vehicles and engines for
testing.
* * * * *
(c) You must notify us before disqualifying any vehicle based on
illuminated MIL or stored OBD trouble codes as described in Sec.
1036.415(b)(3), or for any other reasons not specified in paragraph (b)
of this section. For example, notify us if you disqualify any vehicle
because the engine does not represent the engine family or the
vehicle's usage is atypical for the particular application. You do not
need to notify us in advance if the owner declines to participate in
the test program.
0
28. Amend Sec. 1036.415 by:
0
a. Revising paragraph (c) introductory text;
0
b. Adding paragraph (c)(6);
0
c. Revising paragraphs (d) and (g); and
0
d. Adding paragraph (h).
The revisions and additions read as follows:
Sec. 1036.415 Preparing and testing engines.
* * * * *
(c) Use appropriate fluids for testing, as follows:
* * * * *
(6) Perform testing in the as-received condition with respect to
DEF. You may measure the urea concentration of the as-received DEF.
(d) You must test the selected engines using the test procedure
described in Sec. 1036.530 while they remain installed in the vehicle.
Testing consists of characterizing emission rates for moving average
300 second test intervals while driving, with those test intervals
divided into bins representing different types of engine operation over
a shift-day. Measure emissions as follows:
(1) Perform all testing with PEMS and field-testing procedures
referenced in 40 CFR part 1065, subpart J. Measure emissions of
NOX, CO, and CO2. We may require you to also
measure emissions of HC and PM. You may determine HC emissions by any
method specified in 40 CFR 1065.660(b). If we do not require HC
measurement, set xTHCmeas in 40 CFR 1065.655 to zero.
(2) If the engine's crankcase discharges emissions into the ambient
atmosphere, as allowed by Sec. 1036.115(a), you must either route all
crankcase emissions into the exhaust for a combined measurement or add
the crankcase emission values specified in Sec. 1036.240(e) to
represent emission levels at useful life instead of measuring crankcase
emissions in the field.
* * * * *
(g) For stop-start and automatic engine shutdown systems meeting
the specifications of 40 CFR 1037.660, override idle-reduction features
if they are adjustable under 40 CFR 1037.520(j)(4). If those systems
are tamper-resistant under 40 CFR 1037.520(j)(4), set the 1-Hz emission
rate to zero for all regulated pollutants when the idle-reduction
feature is active. Do not exclude these data points under Sec.
1036.530(d)(3)(ii).
(h) For hybrid powertrains that are designed to turn the engine off
at zero vehicle speed, set the 1-Hz emission rate to zero for all
regulated pollutants after the initial engine start for the shift-day
when the engine is off, the vehicle speed is zero, and the powertrain
is keyed on. Do not exclude these data points under Sec.
1036.530(d)(3)(ii).
0
29. Amend Sec. 1036.420 by:
0
a. Revising paragraphs (c) and (d) to read as follows:
Sec. 1036.420 Pass criteria for individual engines.
* * * * *
(c) For engines subject to compression-ignition standards,
determine the number of test intervals for each pollutant in each bin.
A bin is valid under this section only if it has at
[[Page 43235]]
least 2,400 test intervals for bin 1 and at least 10,000 test intervals
for bin 2.
(d) Continue testing and combine valid data from all test intervals
for each measured pollutant from all shift-days to achieve the minimum
test interval requirements for each bin. Combine valid ambient
temperature data, Tamb, from all shift-days, calculate the
arithmetic mean of the ambient temperature,Tamb, as
specified in Sec. 1036.530(i) and use this to calculate the off-cycle
NOX emission standard in Sec. 1036.104(a)(3).
(1) For example, you may perform additional testing to address a
shortfall in reaching the minimum test interval requirements due to any
of the following reasons:
(i) Insufficient shift-day operation as described in Sec.
1036.415(f).
(ii) Excluded data as described in Sec. 1036.530(d)(3).
(iii) Gas analyzer range verification failure according to 40 CFR
1065.935(g)(5)(i).
(iv) Drift verification failure according to 40 CFR
1065.935(g)(5)(ii) or (iii).
(2) You may idle the engine at the end of the shift day if you are
not certain if you achieved at least 2,400 bin 1 test intervals. For
engine designs that shut down the engine during idle as described in
Sec. 1036.415(g) or (h), populate bin 1 with additional test intervals
by setting the 1-Hz emission rate for all regulated pollutants to zero
at the end of the shift day to achieve exactly 2,400 bin 1 test
intervals.
* * * * *
0
30. Amend Sec. 1036.425 by revising paragraph (c) to read as follows:
Sec. 1036.425 Pass criteria for engine families.
* * * * *
(c) If two or more engines tested under paragraphs (a) and (b) of
this section do not comply fully with the off-cycle bin standards, test
additional engines until you have tested a total of ten engines.
Calculate the arithmetic mean of the bin emissions from the ten engine
tests as specified in Sec. 1036.530(h) for each pollutant. Calculate
the arithmetic mean, Tamb, of the ambient temperature from
the ten engine tests as specified in Sec. 1036.530(i) and use this to
calculate the off-cycle NOX emission standard in Sec.
1036.104(a)(3). If the mean values are at or below the off-cycle bin
standards, the engine family passes. If the mean value for any
pollutant is above an off-cycle bin standard, the engine family fails.
* * * * *
0
31. Amend Sec. 1036.430 by:
0
a. Revising paragraph (a)(1)(ii);
0
b. Adding paragraph (a)(2)(x); and
0
c. Revising paragraphs (a)(3)(vii).
The revisions and addition read as follows:
Sec. 1036.430 Reporting requirements.
(a) * * *
(1) * * *
(ii) Include a summary of the vehicles you have disqualified and
the reasons you disqualified them, whether you base the
disqualification on the criteria in Sec. 1036.410(b), owner
nonparticipation, or anything else. If you disqualify the vehicle based
on illuminated MIL or stored OBD trouble codes, describe the MIL or
trouble code information. If you disqualified a vehicle due to
misfueling, include the results of any fuel sample tests. If you reject
a vehicle due to tampering, describe how you determined that tampering
occurred.
* * * * *
(2) * * *
(x) Identify the time and vehicle mileage for adding DEF if the
vehicle needs a DEF refill.
(3) * * *
(vii) The number of test intervals in each bin (see Sec.
1036.420(c)).
* * * * *
0
32. Amend Sec. 1036.501 by:
0
a. Revising paragraph (b) introductory text;
0
b. Redesignating paragraph (b)(3) as paragraph (b)(4);
0
c. Adding a new paragraph (b)(3);
0
d. Revising paragraphs (f) and (h); and
0
e. Adding paragraph (i).
The revisions and additions read as follows:
Sec. 1036.501 General testing provisions.
* * * * *
(b) Use the fuels and engine fluids specified in 40 CFR part 1065
to perform valid tests, as follows:
* * * * *
(3) For engines using selective catalytic reduction, use diesel
exhaust fluid that conforms to the specifications referenced in the
definition of ``diesel exhaust fluid'' in Sec. 1036.801.
* * * * *
(f) You may use special or alternative procedures to the extent we
allow them under 40 CFR 1065.10.
* * * * *
(h) For testing engines that use regenerative braking through the
crankshaft only to power an electric heater for aftertreatment devices,
you may use the nonhybrid engine testing procedures in Sec. Sec.
1036.510, 1036.512, and 1036.514 and you may also or instead use the
fuel mapping procedure in Sec. 1036.505(b)(1) or (2). You may use this
allowance only if the recovered energy is less than 10 percent of the
total positive work for each applicable test interval. Otherwise, use
powertrain testing procedures specified for hybrid powertrains to
measure emissions and create fuel maps. For nonhybrid engines that use
the powertrain test procedures, the provisions specified for nonhybrid
powertrain testing apply. For engines that power an electric heater
with a battery, you must meet the requirements related to charge-
sustaining operation as described in 40 CFR 1066.501(a)(3).
(i) The following figure illustrates an example of a test sequence
for determining criteria pollutant emissions for plug-in hybrid
powertrains:
[[Page 43236]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.029
0
33. Amend Sec. 1036.510 by revising paragraphs (b)(2) introductory
text, (b)(2)(iii) and (vii), (c) introductory text, (c)(3), (d), (e),
and (g) to read as follows:
Sec. 1036.510 Supplemental Emission Test.
* * * * *
(b) * * *
(2) Test hybrid powertrains as described in Sec. 1036.545, except
as specified in this paragraph (b)(2). Do not compensate the duty cycle
for the distance driven as described in Sec. 1036.545(g)(4). You may
set the battery to the lowest SOC level that results in charge
sustaining operation after preconditioning to help meet the NEC
requirement described in Sec. 1036.545(a)(6). Follow 40 CFR
1065.610(d)(3)(ii) for applying optional declared accessory loads. For
hybrid engines, select the transmission model parameters as described
in Sec. 1036.510(b)(2)(viii). Disregard duty cycles in Sec.
1036.545(j). For cycles that begin with idle, leave the transmission in
neutral or park for the full initial idle segment. Place the
transmission into drive no earlier than 5 seconds before the first
nonzero vehicle speed setpoint.
[[Page 43237]]
For SET testing only, place the transmission into park or neutral when
the cycle reaches the final idle segment. Use the following vehicle
parameters instead of those in Sec. 1036.545 to define the vehicle
model in Sec. 1036.545(a)(3):
* * * * *
(iii) Determine the vehicle drag area, CdA, as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.030
Where:
g = gravitational constant = 9.80665 m/s\2\.
r = air density at reference conditions. Use r = 1.1845 kg/m\3\.
Example:
[GRAPHIC] [TIFF OMITTED] TP14JY26.031
CdA = 4.69 m\2\
* * * * *
(vii) Select a combination of drive axle ratio, ka, and
a tire radius, r, that represents the worst-case combination of top
gear ratio, drive axle ratio, and tire size for CO2
emissions expected for vehicles in which the hybrid engine or hybrid
powertrain will be installed. This is typically the highest axle ratio
and smallest tire radius. Disregard configurations or settings
corresponding to a maximum vehicle speed below 60 mi/hr in selecting a
drive axle ratio and tire radius, unless you can demonstrate that in-
use vehicles will not exceed that speed. You may request preliminary
approval for selected drive axle ratio and tire radius consistent with
the provisions of Sec. 1036.210. If the hybrid engine or hybrid
powertrain is used exclusively in vehicles not capable of reaching 60
mi/hr, you may request that we approve an alternative test cycle and
cycle-validation criteria as described in 40 CFR 1066.425(b)(5). Note
that hybrid engines rely on a specified transmission that is different
for each duty cycle; the transmission's top gear ratio therefore
depends on the duty cycle, which will in turn change the selection of
the drive axle ratio and tire size. For example, Sec. 1036.520
prescribes a different top gear ratio than this paragraph (b)(2).
* * * * *
(c) Measure emissions using the SET duty cycle shown in Table 1 of
this section to determine whether engines meet the emission standards
specified in subpart B of this part. Table 1 of this section specifies
test settings, as follows:
* * * * *
(3) Table 2 follows:
[[Page 43238]]
Table 2 to Paragraph (c)(3) of Sec. 1036.510--Supplemental Emission Test
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Engine testing Hybrid powertrain testing
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SET mode Time in Road-grade coefficients
mode Engine speed a b Torque (percent) b c Vehicle speed (mi/hr) ---------------------------------------------------------------------------------------------------------------
(seconds) a b c d e f g h
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1a Steady-state.................... 124 Warm Idle............. 0..................... 0..................... 0 0 0 0 0 0 0 0
1b Transition \d\.................. 20 Linear Transition..... Linear Transition..... Linear Transition..... -1.898E-08 -5.895E-07 3.780E-05 4.706E-03 6.550E-04 -2.679E-02 -1.027E+00 1.542E+01
2a Steady-state.................... 196 A..................... 100................... vrefA................. -1.227E-08 -5.504E-07 3.946E-05 1.212E-03 5.289E-04 -3.116E-02 -3.227E-01 1.619E+01
2b Transition \d\.................. 20 Linear Transition..... Linear Transition..... Linear Transition..... -2.305E-09 -4.873E-07 2.535E-05 8.156E-04 4.730E-04 -2.383E-02 -2.975E-01 1.277E+01
3a Steady-state.................... 220 B..................... 50.................... vrefB................. 8.296E-09 -4.752E-07 1.291E-05 2.880E-04 4.524E-04 -1.802E-02 -1.830E-01 8.810E+00
3b Transition...................... 20 B..................... Linear Transition..... vrefB................. 4.642E-09 -5.143E-07 1.991E-05 3.556E-04 4.873E-04 -2.241E-02 -2.051E-01 1.068E+01
4a Steady-state.................... 220 B..................... 75.................... vrefB................. 1.818E-10 -5.229E-07 2.579E-05 5.575E-04 5.006E-04 -2.561E-02 -2.399E-01 1.287E+01
4b Transition \d\.................. 20 Linear Transition..... Linear Transition..... Linear Transition..... 5.842E-10 -4.992E-07 2.244E-05 4.700E-04 4.659E-04 -2.203E-02 -1.761E-01 1.072E+01
5a Steady-state.................... 268 A..................... 50.................... vrefA................. 3.973E-09 -4.362E-07 1.365E-05 4.846E-04 4.158E-04 -1.606E-02 -1.908E-01 8.206E+00
5b Transition...................... 20 A..................... Linear Transition..... vrefA................. -2.788E-10 -4.226E-07 1.812E-05 6.591E-04 4.158E-04 -1.846E-02 -2.201E-01 1.001E+01
6a Steady-state.................... 268 A..................... 75.................... vrefA................. -4.216E-09 -4.891E-07 2.641E-05 8.796E-04 4.692E-04 -2.348E-02 -2.595E-01 1.226E+01
6b Transition...................... 20 A..................... Linear Transition..... vrefA................. 3.979E-09 -4.392E-07 1.411E-05 2.079E-04 4.203E-04 -1.658E-02 -1.655E-01 7.705E+00
7a Steady-state.................... 268 A..................... 25.................... vrefA................. 1.211E-08 -3.772E-07 6.209E-07 1.202E-04 3.578E-04 -8.420E-03 -1.248E-01 4.189E+00
7b Transition \d\.................. 20 Linear Transition..... Linear Transition..... Linear Transition..... 1.659E-09 -4.954E-07 2.103E-05 4.849E-04 4.776E-04 -2.194E-02 -2.551E-01 1.075E+01
8a Steady-state.................... 196 B..................... 100................... vrefB................. -8.232E-09 -5.707E-07 3.900E-05 8.150E-04 5.477E-04 -3.325E-02 -2.956E-01 1.689E+01
8b Transition...................... 20 B..................... Linear Transition..... vrefB................. 4.286E-09 -5.150E-07 2.070E-05 5.214E-04 4.882E-04 -2.291E-02 -2.271E-01 1.157E+01
9a Steady-state.................... 196 B..................... 25.................... vrefB................. 1.662E-08 -4.261E-07 -2.705E-07 2.098E-05 4.046E-04 -1.037E-02 -1.263E-01 4.751E+00
9b Transition \d\.................. 20 Linear Transition..... Linear Transition..... Linear Transition..... 7.492E-09 -5.451E-07 1.950E-05 2.243E-04 5.114E-04 -2.331E-02 -2.270E-01 1.062E+01
10a Steady-state................... 28 C..................... 100................... vrefC................. -1.073E-09 -5.904E-07 3.477E-05 5.069E-04 5.647E-04 -3.354E-02 -2.648E-01 1.651E+01
10b Transition..................... 20 C..................... Linear Transition..... vrefC................. 9.957E-09 -5.477E-07 1.826E-05 2.399E-04 5.196E-04 -2.410E-02 -2.010E-01 1.128E+01
11a Steady-state................... 4 C..................... 25.................... vrefC................. 1.916E-08 -5.023E-07 3.715E-06 3.634E-05 4.706E-04 -1.539E-02 -1.485E-01 6.827E+00
11b Transition..................... 20 C..................... Linear Transition..... vrefC................. 1.474E-08 -5.176E-07 1.027E-05 1.193E-04 4.911E-04 -1.937E-02 -1.713E-01 8.872E+00
12a Steady-state................... 4 C..................... 75.................... vrefC................. 6.167E-09 -5.577E-07 2.354E-05 3.524E-04 5.319E-04 -2.708E-02 -2.253E-01 1.313E+01
12b Transition..................... 20 C..................... Linear Transition..... vrefC................. 1.039E-08 -5.451E-07 1.756E-05 2.257E-04 5.165E-04 -2.366E-02 -1.978E-01 1.106E+01
13a Steady-state................... 4 C..................... 50.................... vrefC................. 6.209E-09 -5.292E-07 2.126E-05 3.475E-04 5.132E-04 -2.552E-02 -2.212E-01 1.274E+01
13b Transition \d\................. 20 Linear Transition..... Linear Transition..... Linear Transition..... 4.461E-09 -6.452E-07 1.301E-05 1.420E-03 5.779E-04 -1.564E-02 1.949E-01 7.998E+00
14 Steady-state.................... 144 Warm Idle............. 0..................... 0..................... 0 0 0 0 0 0 0 0
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Engine speed terms are defined in 40 CFR part 1065.
\b\ Advance from one mode to the next within a 20 second transition phase. During the transition phase, command a linear progression from the settings of the current mode to the settings of the next mode.
\c\ The percent torque is relative to maximum torque at the commanded engine speed.
\d\ Use the average vehicle speed during each transition for vref in Eq. 1036.510-7 for calculating road grade for all points during the transition.
[[Page 43239]]
(d) Determine criteria pollutant emissions for plug-in hybrid
powertrains for charge-sustaining operation as described in paragraph
(b)(2) of this section.
(e) Determine greenhouse gas pollutant emissions for plug-in hybrid
powertrains using the emissions results for all the SET test intervals
for both charge-depleting and charge-sustaining operation as follows:
(1) Carry out a charge-depleting test as described in paragraph
(b)(2) of this section, except as follows:
(i) Fully charge the RESS after preconditioning.
(ii) Operate the engine or powertrain continuously over repeated
SET duty cycles until you reach the end-of-test criterion defined in 40
CFR 1066.501(a)(3).
(iii) Calculate emission results for each SET duty cycle. Figure 1
to paragraph (e)(3) of this section provides an example of a charge-
depleting test sequence where there are two test intervals that contain
engine operation.
(2) Report the highest emission result for each GHG pollutant from
all tests in paragraph (e)(1) of this section, even if those individual
results come from different test intervals.
(3) The following figure illustrates an example of an SET charge-
depleting test sequence:
[GRAPHIC] [TIFF OMITTED] TP14JY26.032
(4) Calculate the utility factor-weighted composite mass of
emissions from the charge-depleting and charge-sustaining test results,
eUF[emission]comp, using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.033
Where:
i = an indexing variable that represents one test interval.
N = total number of charge-depleting test intervals.
e[emission][int]CDi = total mass of emissions in the
charge-depleting portion of the test for each test interval, i,
starting from i = 1, including the test interval(s) from the
transition phase.
UFDCDi = utility factor fraction at distance
DCDi from Eq. 1036.510-11, as determined by interpolating
the approved utility factor curve for each test interval, i,
starting from i = 1. Let UFDCD0 = 0.
j = an indexing variable that represents one test interval.
M = total number of charge-sustaining test intervals.
e[emission][int]CSj = total mass of emissions in the
charge-sustaining portion of the test for each test interval, j,
starting from j = 1.
UFRCD = utility factor fraction at the full charge-
depleting distance, RCD, as
[[Page 43240]]
determined by interpolating the approved utility factor curve.
RCD is the cumulative distance driven over N charge-
depleting test intervals.
[GRAPHIC] [TIFF OMITTED] TP14JY26.034
Where:
k = an indexing variable that represents one recorded velocity
value.
Q = total number of measurements over the test interval.
v = vehicle velocity at each time step, k, starting from k = 1. For
tests completed under this section, v is the vehicle velocity from
the vehicle model in Sec. 1036.545. Note that this should include
charge-depleting test intervals that start when the engine is not
yet operating.
[Delta]t = 1/frecord
frecord = the record rate.
Example using the charge-depletion test in figure 1 to paragraph
(d)(4) of this section for the SET for CO2 emission determination:
Q = 24000
v1 = 0 mi/hr
v2 = 0.8 mi/hr
v3 = 1.1 mi/hr
frecord = 10 Hz
[Delta]t = 1/10 Hz = 0.1 s
DCD1 = [Sigma]24000k=1 (0 [middot] 0.1
+ 0.8 [middot] 0.1 + 1.1 [middot] 0.1 + v24000 [middot]
[Delta]t)
DCD1 = 30.1 mi
DCD2 = 30.0 mi
DCD3 = 30.1 mi
DCD4 = 30.2 mi
DCD5 = 30.1 mi
N = 5
UFDCD1 = 0.11
UFDCD2 = 0.23
UFDCD3 = 0.34
UFDCD4 = 0.45
UFDCD5 = 0.53
eCO2SETCD1 = 0 g/hp[middot]hr
eCO2SETCD2 = 0 g/hp[middot]hr
eCO2SETCD3 = 0 g/hp[middot]hr
eCO2SETCD4 = 0 g/hp[middot]hr
eCO2SETCD5 = 174.4 g/hp[middot]hr
M = 1
eCO2SETCS = 428.1 g/hp[middot]hr
UFRCD = 0.53
[GRAPHIC] [TIFF OMITTED] TP14JY26.035
eUFCO2comp = 215.2 g/hp[middot]hr
* * * * *
(g) Calculate the total emission mass of each constituent, m, over
the test interval as described in 40 CFR 1065.650. Calculate the total
work, W, over the test interval as described in 40 CFR 1065.650(d),
with the following exceptions for testing hybrid powertrains:
(1) Determine shaft power at each point during the test interval
using system power, Psys, from Sec. 1036.520(f) instead of
calculating shaft power according to 40 CFR 1065.650(d)(2).
(2) Do not set power values to zero as described in 40 CFR
1065.650(d)(6).
(3) For criteria pollutant charge sustaining tests, where the net
energy change tolerance is greater than 1 percent and less than or
equal to 5 percent, subtract net energy change from the battery
determined from 40 CFR 1066.501(a)(3) from the total work determined
from this paragraph (g) and 40 CFR 1065.650(d).
0
34. Amend Sec. 1036.512 by revising paragraphs (c) and (d) to read as
follows:
Sec. 1036.512 Federal Test Procedure.
* * * * *
(c) Except as specified in paragraph (d) of this section for plug-
in hybrid powertrains, the FTP duty cycle consists of an initial run
through the test interval from a cold start as described in 40 CFR part
1065, subpart F, followed by a (20 1) minute hot soak with
no engine operation, and then a final hot start run through the same
transient test interval. Engine starting is part of both the cold-start
and hot-start test intervals. Calculate the total emission mass of each
constituent, m, and the total work, W, over the test interval as
described in Sec. 1036.510(g). For powertrains with automatic
transmissions, account for and include the work produced by the engine
from the CITT load. Calculate the official transient emission result
from the cold-start and hot-start test intervals using the following
equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.036
(d) Determine criteria pollutant emissions for plug-in hybrid
powertrains as follows:
(1) Carry out a charge-depleting test as described in paragraph
(b)(2) of this section, except as follows:
(i) Precondition the engine or powertrain as described in 40 CFR
1065.518(c)(1).
(ii) Fully charge the RESS after preconditioning.
(iii) Operate it over one FTP duty cycle followed by alternating
repeats of a 20-minute soak and a hot start test interval until you
reach the end-of-test criteria defined in 40 CFR 1066.501(a)(3).
(iv) Calculate the composite emission result by treating the first
test interval with engine operation and the subsequent test interval as
the cold-start test intervals and the test interval that follows those
two as the hot-start test interval. Figure 1 to paragraph (d)(4) of
this section provides an example of a charge-depleting test sequence
where the fifth and sixth test intervals are the cold-start test
intervals while the seventh is the hot-start test interval. Calculate
the official transient emission result from the cold-start and hot-
start test intervals using the following equation:
[[Page 43241]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.037
(2) Carry out a charge-sustaining test as described in paragraphs
(b)(2) and (c) of this section.
(3) Report the highest composite emission result from all FTP duty-
cycles for each criteria pollutant from all tests in paragraphs (d)(1)
and (2) of this section, even if those individual results come from
different test intervals.
(4) The following figure illustrates an example of an FTP charge-
depleting test sequence:
[GRAPHIC] [TIFF OMITTED] TP14JY26.038
(5) The following figure illustrates an example of an FTP charge-
sustaining test sequence:
[[Page 43242]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.039
* * * * *
0
35. Amend Sec. 1036.514 by revising paragraphs (a)(1)(i), (b), and (d)
to read as follows:
Sec. 1036.514 Low Load Cycle.
* * * * *
(a) * * *
(1) * * *
(i) Apply the accessory load at idle in paragraph (c) of this
section using declared idle power as described in 40 CFR
1065.510(f)(6). The option of declaring a nonzero torque under 40 CFR
1065.510(f)(5)(iii) does not apply.
* * * * *
(b) Test hybrid powertrains as described in Sec. 1036.510(b)(2),
with the following exceptions:
(1) Replace ``SET'' with ``LLC''.
(2) Replace Pcontrated with Prated, which is
the peak rated power determined in Sec. 1036.520.
(3) Keep the transmission in drive for all idle segments 200
seconds or less. For idle segments more than 200 seconds, leave the
transmission in drive for the first 3 seconds of the idle segment, then
immediately place the transmission in park or neutral, and shift the
transmission into drive again 3 seconds before the end of the idle
segment. The end of the idle segment occurs at the first nonzero
vehicle speed setpoint.
(4) For hybrid engines, you may request to change the GEM-generated
engine reference torque at idle to better represent curb idle
transmission torque (CITT).
(5) Calculate and evaluate cycle-validation criteria as specified
in Sec. 1036.545.
* * * * *
(d) Except as specified in paragraph (b)(4) of this section for
plug-in hybrid powertrains, the test sequence consists of
preconditioning the engine by running one or two FTPs with each FTP
followed by (20 1) minutes with no engine operation and a
hot start run through the LLC. You may start any preconditioning FTP
with a hot engine. Perform testing as described in 40 CFR 1065.530 for
a test interval that includes engine starting. Calculate the total
emission mass of each constituent, m, and the total work, W, over the
test interval as described in Sec. 1036.510(g). Do not exclude
accessory loads specified in paragraph (c) of this section when
calculating W. For powertrains with automatic transmissions, account
for and include the work produced by the engine from the CITT load.
* * * * *
0
36. Amend Sec. 1036.520 by
0
a. Revising paragraphs (d), (e), (f)(1), and (h) through (k); and
0
b. Adding a new paragraph (l); and
These revisions and addition read as follows:
Sec. 1036.520 Determining power and vehicle speed values for
powertrain testing.
* * * * *
(d) Carry out the test as described in this paragraph (d). The
state-of-charge of the RESS must be at a representative level to
deliver maximum power.
(1) Warm up the powertrain with one FTP duty-cycle that you
denormalized using the manufacturer declared Pcontrated.
(2) Ramp the vehicle speed to 5 mi/hr with a grade of 0 percent
over 5 seconds and dwell at this speed and grade for 5 seconds.
(3) Ramp to maximum driver demand for a full load acceleration
within 3 seconds at 6.0 percent road grade, continuing for 268 seconds.
(4) Linearly ramp the grade from 6.0% down to 0.0% over 300
seconds. Stop the test after the acceleration is less than 0.02 m/s\2\.
(e) Record the powertrain system angular speed and torque values
measured at the dynamometer at 100 Hz and use these in conjunction with
the vehicle model to calculate vehicle system power,
Psys,vehicle. Note that Psys, is the
corresponding value for system power at a location that represents the
engine's primary output shaft on a conventional powertrain.
(f) * * *
(1) For testing with the speed and torque measurements at the
engine's primary output shaft, Psys is equal to the
calculated vehicle system power, Psys,vehicle, determined in
paragraphs (d) and (e) of this section.
* * * * *
(h) Determine measured rated power, Pratedmeas, as the
maximum measured power from the data collected in paragraph (d)(2) of
this section where the COV determined in paragraph (g) of this section
is less than 0.5 percent.
(i) Determine rated power, Prated, as follows:
(1) For nonhybrid powertrains Prated equals
Pratedmeas.
(2) For hybrid powertrains, Prated is the lower of
Pratedmeas and the following values:
(i) 260 kW for Spark-ignition HDE and Light HDE.
(ii) 340 kW for Medium HDE.
(iii) 450 kW for Heavy HDE.
[[Page 43243]]
(j) Determine continuous rated power, Pcontrated, as
follows:
(1) For nonhybrid powertrains, Pcontrated equals
Prated.
(2) For hybrid powertrains, Pcontrated is the smaller of
the following values:
(i) The maximum measured power from the data collected in paragraph
(d)(4) of this section where the COV determined in paragraph (g) of
this section is less than 0.5 percent.
(ii) Prated from paragraph (i) of this section.
(k) Determine vehicle C speed, vrefC, as follows:
(1) If the maximum Psys(t) in the highest gear during
the maneuver in paragraph (d)(4) of this section is greater than
0.98[middot]Pcontrated, vrefC is the average of
the minimum and maximum vehicle speeds where Psys(t) is
equal to 0.98[middot]Pcontrated during the maneuver in
paragraph (d)(4) where the transmission is in the highest gear, using
linear interpolation, as appropriate. If Psys(t) at the
lowest vehicle speed where the transmission is in the highest gear is
greater than 0.98[middot]Pcontrated, use the lowest vehicle
speed where the transmission is in the highest gear as the minimum
vehicle speed input for calculating vrefC.
(2) Otherwise, vrefC is the maximum vehicle speed during
the maneuver in paragraph (d)(4) of this section where the transmission
is in the highest gear.
(3) You may use a declared vrefC instead of measured
vrefC if the declared vrefC is within (97.5 to
102.5) % of the corresponding measured value.
(4) Manufacturers may request approval to use an alternative
vehicle C speed in place of the measured vehicle C speed determined in
this paragraph (k) for series hybrid applications. Approval will be
contingent upon justification that the measured vehicle C speed is not
representative of the expected real-world cruise speed.
(l) If Pcontrated as determined in paragraph (j) of this
section is within 3 percent of the manufacturer-declared
value, use the manufacturer-declared value. In addition, for nonhybrid
powertrains set Prated to declared Pcontrated.
Otherwise, repeat the procedure in paragraphs (b) through (k) of this
section and use Pcontrated from paragraph (j) instead of the
manufacturer-declared value.
0
37. Amend Sec. 1036.525 by revising paragraph (b)(3) to read as
follows:
Sec. 1036.525 Clean Idle test.
* * * * *
(b) * * *
(3) Start sampling emissions 10 minutes after reaching the speed
and torque setpoints and continue emission sampling and engine
operation at those setpoints. Stop emission sampling after 1800 seconds
to complete the test interval.
* * * * *
0
38. Revise and republish Sec. 1036.530 to read as follows:
Sec. 1036.530 Test procedures for off-cycle testing.
(a) General. This section describes the measurement and calculation
procedures to perform field testing and determine whether tested
engines and engine families meet emission standards under subpart E of
this part. Calculate mass emission rates as specified in 40 CFR part
1065, subpart G. Use good engineering judgment to adapt these
procedures for simulating vehicle operation in the laboratory.
(b) Vehicle preparation and measurement procedures. (1) Set up the
vehicle for testing with a portable emissions measurement system (PEMS)
as specified in 40 CFR part 1065, subpart J.
(2) Begin emission sampling and data collection as described in 40
CFR 1065.935(c)(3) before starting the engine at the beginning of the
shift-day. Start the engine only after confirming that engine coolant
temperature is at or below 40 [deg]C.
(3) Measure emissions over one or more shift-days as specified in
subpart E of this part.
(4) For engines subject to compression-ignition standards, record 1
Hz measurements of ambient temperature near the vehicle.
(c) Drift verification. Perform drift verification as described in
40 CFR 1065.935(g)(5)(ii) and (iii). For drift verification of CO and
HC, determine a corrected value of the off-cycle emission quantity for
bin 2 from Eq. 1036.530-3 for each interval between analyzer
verifications. Compare that corrected value to the uncorrected value or
to the bin 2 emission standard in Sec. 1036.104(a)(3), whichever is
greater, to determine whether drift is within the specified percentage
limit.
(d) Test Intervals. Determine the test intervals as follows:
(1) Spark-ignition. Create a single test interval that covers the
entire shift-day for engines subject to spark-ignition standards. The
test interval starts with the first pair of consecutive data points
with no exclusions as described in paragraph (d)(3) of this section
after the start of the shift-day and ends with the last pair of
consecutive data points with no exclusions before the end of the shift
day.
(2) Compression-ignition. Create a series of 300 second test
intervals for engines subject to compression-ignition standards
(moving-average test intervals) as follows:
(i) Begin and end each test interval with a pair of consecutive
data points with no exclusions as described in paragraph (d)(3) of this
section. Select the last data point of each test interval such that the
test interval includes 300 seconds of data with no exclusions, as
described in paragraph (e) of this section. The test interval may be a
fraction of a second more or less than 300 seconds to account for the
precision of the time stamp in recording 1 Hz data. A test interval may
include up to 599 seconds of data with continuous exclusions;
invalidate any test interval that includes at least 600 seconds of
continuous sampling with excluded data.
(ii) The first 300 second test interval starts with the first pair
of consecutive data points with no exclusions. Determine the start of
each subsequent 300 second test interval by finding the first pair of
consecutive data points with no exclusions after the initial data point
of the previous test interval.
(iii) The last 300 second test interval ends with the last pair of
consecutive data points with no exclusions before the end of the shift
day.
(3) Excluded data. Exclude data from test intervals for any period
meeting one or more of the following conditions:
(i) An analyzer or flow meter is performing zero and span drift
checks or zero and span calibrations, including any time needed for the
analyzer to stabilize afterward, consistent with good engineering
judgment.
(ii) The engine is off, except as specified in Sec. 1036.415(g)
and (h).
(iii) The engine is performing an infrequent regeneration. Do not
exclude data related to any other AECDs, except as specified in
paragraph (d)(3)(vi) of this section.
(iv) The recorded ambient air temperature is below 5 [deg]C or
above the temperature calculated using the following equation.
[GRAPHIC] [TIFF OMITTED] TP14JY26.040
Where:
h = recorded elevation of the vehicle in feet above sea level (h is
negative for elevations below sea level).
Example:
h = 2679 ft
Tmax = -0.0014 [middot] 2679 + 37.78
Tmax = 34.0 [deg]C
(v) The vehicle is operating at an elevation more than 5,500 feet
above sea level.
[[Page 43244]]
(vi) An engine has one or more active AECDs for emergency vehicles
under Sec. 1036.115(h)(4).
(vii) A single data point does not meet any of the conditions
specified in paragraphs (d)(3)(i) through (vi) of this section, but it
is preceded and followed by data points that both meet one or more of
the specified exclusion conditions.
(viii) Gas analyzer range validation failure according to 40 CFR
1065.935(g)(5)(i).
(ix) Any data not meeting the drift requirements in paragraph (c)
of this section.
(e) Assembling test intervals. A test interval may include multiple
subintervals separated by periods with one or more exclusions under
paragraph (d)(3) of this section.
(1) Treat these test subintervals as continuous for calculating
duration of the test interval for engines subject to compression-
ignition standards.
(2) Calculate emission mass during each test subinterval and sum
those subinterval emission masses to determine the emission mass over
the test interval. Calculate emission mass as described in 40 CFR
1065.650(c)(2)(i), with the following exceptions and clarifications:
(i) Correct NOX emissions for humidity as specified in
40 CFR 1065.670. Calculate corrections relative to ambient air humidity
as measured by PEMS.
(ii) Disregard the provision in 40 CFR 1065.650(g) for setting
negative emission mass to zero for test intervals and subintervals.
(iii) Calculation of emission mass in 40 CFR 1065.650 assumes a
constant time interval, [Delta]t. If it is not appropriate to assume
[Delta]t is constant for testing under this section, use good
engineering judgment to record time at each data point and adjust the
mass calculation from Eq. 1065.650-4 by treating [Delta]t as a
variable.
(f) Normalized CO2 emission mass over a 300 second test
interval. For engines subject to compression-ignition standards,
determine the normalized CO2 emission mass over each 300
second test interval, mCO2,norm,testinterval, to the nearest
0.01% using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.041
Where:
mCO2,testinterval = total CO2 emission mass
over the test interval.
eCO2FTPFCL = the engine's FCL for CO2 over the
FTP duty cycle or, for plug-in hybrid powertrains, the charge-
sustaining CO2 emissions over the FTP duty cycle. If the
engine family includes no FTP testing, use the engine's FCL for
CO2 over the SET duty cycle.
Pmax = the highest value of rated power for all the
configurations included in the engine family.
ttestinterval = duration of the test interval. Note that
the nominal value is 300 seconds.
Example:
mCO2,testinterval = 3948 g
eCO2FTPFCL = 428.2 g/hp[middot]hr
Pmax = 406.5 hp
ttestinterval = 300.01 s = 0.08 hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.042
mCO2,norm,testinterval = 0.2722 = 27.22%
(g) Binning 300 second test intervals. For engines subject to
compression-ignition standards, identify the appropriate bin for each
of the 300 second test intervals based on its normalized CO2
emission mass, mCO2,norm,testinterval, as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.120
(h) Off-cycle emissions quantities. Determine the off-cycle
emissions quantities as follows:
(1) Spark-ignition. For engines subject to spark-ignition
standards, the off-cycle emission quantity,
e[emission],offcycle, is the value for CO2-
specific emission mass for a given pollutant over the test interval
representing the shift-day converted to a brake-specific value, as
calculated for each measured pollutant using the following equation:
[[Page 43245]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.043
Where:
m[emission] = total emission mass for a given pollutant
over the test interval as determined in paragraph (e)(2) of this
section.
mCO2 = total drift-corrected CO2 emission mass
over the test interval as determined in paragraph (e)(2) of this
section.
eCO2,FTP,FCL = the engine's FCL for CO2 over
the FTP duty cycle.
Example:
mNOx = 1.337 g
mCO2 = 18778 g
eCO2,FTP,FCL = 505.1 g/hp [middot] hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.044
eNOx,offcycle = 0.035 g/hp [middot] hr
(2) Compression-ignition. For engines subject to compression-
ignition standards, determine the off-cycle emission quantity for each
bin. When calculating mean bin emissions from ten engines to apply the
pass criteria for engine families in Sec. 1036.425(c), set any
negative off-cycle emissions quantity to zero before calculating mean
bin emissions.
(i) Off-cycle emissions quantity for bin 1. The off-cycle emission
quantity for bin 1, mNOx,offcycle,bin1, is the mean
NOX mass emission rate from all test intervals associated
with bin 1 as calculated using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.045
Where:
i = an indexing variable that represents one 300 second test
interval.
N = total number of 300 second test intervals in bin 1.
mNOxtestinterval,i = total NOX emission mass
over the test interval i in bin 1 as determined in paragraph (e)(2)
of this section.
ttestinterval,i = total time of test interval i in bin 1
as determined in paragraph (e)(1) of this section. Note that the
nominal value is 300 seconds.
Example:
N = 10114
mNOx,testinterval,1 = 0.021 g
mNOx,testinterval,2 = 0.025 g
mNOx,testinterval,3 = 0.031 g
ttestinterval,1 = 299.99 s
ttestinterval,2 = 299.98 s
ttestinterval,3 = 300.04 s
[GRAPHIC] [TIFF OMITTED] TP14JY26.046
mNOx,offcycle,bin1 = 0.000285 g/s = 1.026 g/hr
(ii) Off-cycle emissions quantity for bin 2. The off-cycle emission
quantity for bin 2, e[emission],offcycle,bin2, is the value
for CO2-specific emission mass for a given pollutant of all
the 300 second test intervals in bin 2 combined and converted to a
brake-specific value, as calculated for each measured pollutant using
the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.047
Where:
i = an indexing variable that represents one 300 second test
interval.
N = total number of 300 second test intervals in bin 2.
m[emission],testinterval,i = total emission mass for a
given pollutant over the test interval i in bin 2 as determined in
paragraph (e)(2) of this section.
mCO2,testinterval,i = total CO2 emission mass
over the test interval i in bin 2 as determined in paragraph (e)(2)
of this section.
eCO2,FTP,FCL = the engine's FCL for CO2 over
the FTP duty cycle.
Example:
N = 15439
mNOx1 = 0.546 g
mNOx2 = 0.549 g
mNOx3 = 0.556 g
mCO2,1 = 10950.2 g
mCO2,2 = 10961.3 g
mCO2,3 = 10965.3 g
eCO2,FTP,FCL = 428.1 g/hp [middot] hr
[[Page 43246]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.048
eNOx,offcycle,bin2 = 0.026 g/hp[middot]hr = 26 mg/hp
[middot] hr
(i) Shift-day ambient temperature. For engines subject to
compression-ignition standards, determine the mean shift-day ambient
temperature, Tamb, considering only temperature readings
corresponding to data with no exclusions under paragraph (d)(3) of this
section.
(j) Graphical illustration. Figure 1 of this section illustrates a
test interval with interruptions of one or more data points excluded
under paragraph (d)(3) of this section. The x-axis is time and the y-
axis is the mass emission rate at each data point, m(t). The data
points coincident with any exclusion are illustrated with open circles.
The shaded area corresponding to each group of closed circles
represents the total emission mass over that test subinterval. Note
that negative values of m(t) are retained and not set to zero in the
numerical integration calculation. The first group of data points
without any exclusions is referred to as the first test subinterval and
so on.
[GRAPHIC] [TIFF OMITTED] TP14JY26.049
(k) Fuel other than carbon-containing. The following procedures
apply for testing engines using at least one fuel that is not a carbon-
containing fuel:
(1) Use the following equation to determine the normalized
equivalent CO2 emission mass over each 300 second test
interval instead of Eq. 1036.530-2:
[GRAPHIC] [TIFF OMITTED] TP14JY26.050
Where:
Wtestinterval = total positive work over the test
interval from both the engine and hybrid components, if applicable,
as described in Sec. 1036.510(g).
Pmax = the highest value of rated power for all the
configurations included in the engine family.
ttestinterval = duration of the test interval. Note that
the nominal value is 300 seconds.
Example:
Wtestinterval = 8.95 hp[middot]hr
Pmax = 406.5 hp
ttestinterval = 300.01 s = 0.08 hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.051
[[Page 43247]]
mCO2,norm,testinterval = 0.2722
mCO2,norm,testinterval = 27.22%
(2) Determine off-cycle emissions quantities as follows:
(i) For engines subject to spark-ignition standards, use the
following equation to determine the off-cycle emission quantity instead
of Eq. 1036.530-3:
[GRAPHIC] [TIFF OMITTED] TP14JY26.052
Where:
m[emission] = total emission mass for a given pollutant
over the test interval as determined in paragraph (e)(2) of this
section.
Wtestinterval = total positive work over the test
interval as determined in 40 CFR 1065.650.
Example:
mNOx = 1.337 g
Wtestinterval = 38.2 hp[middot]hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.053
eNOx,offcycle = 0.035 g/hp[middot]hr = 35 mg/hp[middot]hr
(ii) For engines subject to compression-ignition standards, use Eq.
1036.530-4 to determine the off-cycle emission quantity for bin 1.
(iii) For engines subject to compression-ignition standards, use
the following equation to determine the off-cycle emission quantity for
bin 2 instead of Eq. 1036.530-5:
[GRAPHIC] [TIFF OMITTED] TP14JY26.054
Where:
i = an indexing variable that represents one 300 second test
interval.
N = total number of 300 second test intervals in bin 2.
m[emission],testinterval,i = total emission mass for a
given pollutant over the test interval i in bin 2 as determined in
paragraph (e)(2) of this section.
Wtestinterval,i = total positive work over the test
interval i in bin 2 as determined in 40 CFR 1065.650.
Example:
N = 15439
mNOx1 = 0.546 g
mNOx2 = 0.549 g
mNOx3 = 0.556 g
Wtestinterval1 = 8.91 hp[middot]hr
Wtestinterval2 = 8.94 hp[middot]hr
Wtestinterval3 = 8.89 hp[middot]hr
[GRAPHIC] [TIFF OMITTED] TP14JY26.055
eNOx,offcycle,bin2 = 0.026 g/hphr = 26 mg/
hp[middot]hr
0
39. Amend Sec. 1036.545 by:
0
a. Revising paragraphs (a)(3)(i) and (ii) and (a)(6);
0
b. Adding and reserving paragraph (a)(12);
0
c. Redesignating paragraph (a)(11) as paragraph (a)(13);
0
d. Adding a new paragraph (a)(11);
0
e. Revising newly redesignated paragraph (a)(13); and
0
f. Revising paragraphs (f)(3), (j)(4), (j)(5), (j)(6), and (m).
The revisions and addition read as follows:
Sec. 1036.545 Powertrain testing.
* * * * *
(a) * * *
(3) * * *
(i) Create driveline and vehicle models that calculate the angular
speed setpoint for the test cell dynamometer,
[fnof]nref,dyno, based on the torque measurement location.
Use the detailed equations in paragraph (f) of this section, the GEM
HIL model's driveline and vehicle submodels, or a combination of the
equations and the submodels. You may use the GEM HIL model's
transmission submodel in paragraph (f) to simulate a transmission only
if testing hybrid engines. For hybrid engines intended for vehicles
with automatic transmissions, update the driver_in_gear signal within
the driver interface block in the GEM HIL model with the transmission
state (in-gear or idle) as a function of time as defined by the duty
cycles in this part.
(ii) Create a driver model or use the GEM HIL model's driver
submodel to simulate a human driver modulating the vehicle speed to
follow the test cycle as closely as possible. Alternatively, a human
driver may modulate the vehicle speed to follow the test cycle as
closely as possible.
* * * * *
(6) The following provisions apply to account for energy coming
from RESS:
(i) For hybrid powertrains with no plug-in capability, correct for
the net energy change of the energy storage device as described in 40
CFR 1066.501(a)(3).
(ii) For plug-in hybrid powertrains, follow 40 CFR 1066.501(a)(3)
to determine End-of-Test for charge-depleting operation. You must get
our approval in advance for your utility factor curve; we will approve
it if you can show that you created it, using good engineering
judgment, from sufficient in-use data of vehicles in the same
application as the vehicles in which the plug-in hybrid electric
powertrain will be installed. You may use methodologies described in
SAE J2841 to develop the utility factor curve.
(iii) For all hybrid powertrains, apply the provisions of 40 CFR
1066.501(a)(3) for charge-sustaining operation during tests to measure
criteria pollutant emissions, except that you must correct for net
energy change as described in Sec. 1036.510(g)(3) and the tolerance
for End-of-Test is 5%.
* * * * *
(11) The test must include all the components of the certified
configuration.
(12) [Reserved]
(13) The following figure provides an overview of testing under
this section:
[[Page 43248]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.056
* * * * *
(f) * * *
(3) Vehicle model. Calculate the simulated vehicle reference speed,
vrefi, using the GEM HIL model's vehicle
[[Page 43249]]
submodel or the equations in this paragraph (f)(3):
[GRAPHIC] [TIFF OMITTED] TP14JY26.057
Where:
i = a time-based counter corresponding to each measurement during
the sampling period. Let vref1 = 0; start calculations at
i = 2. A 10-minute sampling period will generally involve 60,000
measurements.
T = instantaneous measured torque at the axle input, measured at the
wheel hubs, or simulated by the GEM HIL model's transmission
submodel. For configurations with multiple torque measurements, such
as when measuring torque at the wheel hubs, T is the sum of all
torque measurements.
Effaxle = axle efficiency. Use Effaxle = 0.955
for T >= 0, and use Effaxle = 1/0.955 for T < 0. Use
Effaxle = 1.0 if torque is measured at the wheel hubs.
M = vehicle mass for a vehicle class as determined in paragraph (h)
of this section.
g = gravitational constant = 9.80665 m/s2.
Crr = coefficient of rolling resistance for a vehicle
class as determined in paragraph (h) of this section.
Gi-1 = the percent grade interpolated at distance
Di-1 from the grade profile in 40 CFR part 1037, appendix
D. Di-1 is the cumulative distance driven over the test
cycle at time = (i-1). Use the following equation to calculate
Di-1 starting at i = 2:
[GRAPHIC] [TIFF OMITTED] TP14JY26.058
r = air density at reference conditions. Use r = 1.1845 kg/
m3.
CdA = drag area for a vehicle class as determined in
paragraph (h) of this section.
Fbrake,i-1 = instantaneous braking force applied by the
driver model.
[GRAPHIC] [TIFF OMITTED] TP14JY26.059
Dt = the time interval between measurements. For example, at 100 Hz,
Dt = 0.0100 seconds.
Mrotating = inertial mass of rotating components. Let
Mrotating = 340 kg for vocational Light HDV or vocational
Medium HDV. See paragraph (h) of this section for tractors and for
vocational Heavy HDV.
* * * * *
(j) * * *
(4) For plug-in hybrid powertrains, precondition the battery and
then complete all back-to-back tests for each vehicle configuration
according to 40 CFR 1066.501(a)(3) before moving to the next vehicle
configuration. Set the dynamometer target torque to zero when ramping
to the target speed at 1 mi/hr/s. The following figure illustrates a
charge-depleting test sequence with engine operation during two duty
cycles, which are used for criteria pollutant determination:
[GRAPHIC] [TIFF OMITTED] TP14JY26.060
[[Page 43250]]
(5) For non-plug-in hybrid powertrains and plug-in hybrid
powertrains tested as described in paragraph (j)(4) of this section, if
the preceding duty cycle does not end at 0 mi/hr, transition between
duty cycles by decelerating at a rate of 2 mi/hr/s at 0% grade until
the vehicle reaches zero speed. Shut off the powertrain. Prepare the
powertrain and test cell for the next duty cycle. For all other plug-in
hybrid powertrain testing, transition directly to the next duty cycle
without altering vehicle speed.
(6) For non-plug-in hybrid, conventional powertrains, and plug-in
hybrid powertrains tested as described in paragraph (j)(4) of this
section, start the next duty cycle within 60 to 180 seconds after
shutting off the powertrain.
(i) To start the next duty cycle, for hybrid powertrains, key on
the vehicle and then start the duty cycle. For conventional powertrains
key on the vehicle, start the engine, wait for the engine to stabilize
at idle speed, and then start the duty cycle.
(ii) If the duty cycle does not start at 0 mi/hr, transition to the
next duty cycle by accelerating at a target rate of 1 mi/hr/s at 0%
grade. Stabilize for 10 seconds at the initial duty cycle conditions
and start the duty cycle.
* * * * *
(m) Measured output speed validation. For each test point, validate
the measured output speed with the corresponding reference values. If
speed is measured at more than one location, the measurements at each
location must meet validation requirements. If the range of reference
speed is less than 10 percent of the mean reference speed, you need to
meet only the standard error of the estimate in table 4 to this
paragraph (m). You may delete points when the vehicle is stopped or
when a hybrid engine is at idle. If your speed measurement is not at
the location of [fnof]nref, correct your measured speed
using the constant speed ratio between the two locations. You may apply
the time-alignment provisions in 40 CFR 1065.514(c) for up to 0.5
seconds to the reference and measured output speed values. Apply cycle-
validation criteria for each separate transient or highway cruise cycle
based on the following parameters:
Table 4 to Paragraph (m) of Sec. 1036.545--Cycle-Validation Criteria
------------------------------------------------------------------------
Parameter \a\ Speed control
------------------------------------------------------------------------
Slope, a1................................. 0.990 <= a1 <= 1.010.
Absolute value of intercept, <=2.0% of maximum [fnof]nref
[verbar]a0[verbar]. speed.
Standard error of the estimate, SEE....... <=2.0% of maximum [fnof]nref
speed.
Coefficient of determination, r\2\........ >=0.990.
------------------------------------------------------------------------
\a\ Determine values for specified parameters as described in 40 CFR
1065.514(e) by comparing measured and reference values for
[fnof]nref,dyno.
* * * * *
0
40. Amend Sec. 1036.555 by revising paragraph (a) to read as follows:
Sec. 1036.555 Test procedures to verify deterioration factors.
* * * * *
(a) Use PEMS to collect 1 Hz data throughout a shift-day of
driving. Collect all the data elements needed to determine brake-
specific emissions. Calculate emission results using moving average
test intervals as described in Sec. 1036.530.
* * * * *
0
41. Add Sec. 1036.560 to subpart F to read as follows:
Sec. 1036.560 DEF thawing procedure.
Use the following procedure to demonstrate that engines protect
against DEF freezing as specified in Sec. 1036.115(i)(3):
(a) Select a complete or partial vehicle for testing to represent
in-use operation in cold weather.
(b) Start with a full DEF tank that is stabilized to a temperature
at or below -5 [deg]C.
(c) Soak the vehicle at temperatures at or below -17 [deg]C for 72
hours or until the DEF is frozen solid.
(d) Operate the engine at temperatures at or below -17 [deg]C as
follows:
(1) Start the engine and let it idle with no engine load for 20
minutes.
(2) Operate the engine for up to 50 minutes at maximum test speed
and up to 40 percent of the maximum torque available at maximum test
speed.
(e) Determine the time from engine starting to the point at which
the engine is able to consistently inject DEF into the exhaust for
achieving proper catalyst performance.
0
42. Amend Sec. 1036.580 by revising paragraph (b) to read as follows:
Sec. 1036.580 Infrequently regenerating aftertreatment devices.
* * * * *
(b) You may ask us to approve an alternative methodology to account
for regeneration events. We will generally limit approval to cases
where your engines use aftertreatment technology with extremely
infrequent regeneration and you are unable to apply the provisions of
this section.
* * * * *
0
43. Amend Sec. 1036.601 by revising paragraphs (a) introductory text,
(a)(3), and (b)(3) to read as follows:
Sec. 1036.601 Overview of compliance provisions.
(a) Engine and vehicle manufacturers, as well as owners, operators,
and rebuilders of engines subject to the requirements of this part, and
all other persons, must observe the provisions of this part, 40 CFR
part 1068, and the Clean Air Act. The provisions of 40 CFR part 1068
apply for heavy-duty highway engines as specified in that part, subject
to the following provisions:
* * * * *
(3) The warranty-related prohibitions in section 203(a)(4) of the
Clean Air Act (42 U.S.C. 7522(a)(4)) apply to manufacturers of new
heavy-duty highway engines in addition to the prohibitions described in
40 CFR 1068.101(b)(6). We may assess a civil penalty up to $44,539 for
each engine or vehicle in violation. Penalties apply as described in 40
CFR 1068.101.
(b) * * *
(3) Provisions related to nonconformance penalties apply as
described in 40 CFR part 1071. Note that nonconformance penalty
provisions are not available for current or future emission standards
unless we revise the regulation to specify how to apply those
provisions.
* * * * *
0
44. Amend Sec. 1036.605 by revising the section heading, introductory
text, and paragraphs (c) and (d) to read as follows:
Sec. 1036.605 Alternative emission standards for engines used in
specialty vehicles.
Starting in model year 2027, compression-ignition engines at or
above 56 kW and spark-ignition engines of any size that will be
installed in specialty vehicles as allowed by 40 CFR 1037.605 are
exempt from the standards of subpart B of this part if they are
certified under this part to alternative emission standards as follows:
* * * * *
(c) Except as specified in this section, engines certified under
this section must meet all the requirements that apply under 40 CFR
part 1039 or 1048 instead of the comparable provisions in this part.
Before shipping engines under this section, you must have written
assurance from vehicle manufacturers that they need a certain number of
exempted engines under this section. In your annual production report
under 40
[[Page 43251]]
CFR 1039.250 or 1048.250, count these engines separately and identify
the vehicle manufacturers that will be installing them. Treat these
engines as part of the corresponding engine family under 40 CFR part
1039 or 1048 for compliance purposes such as testing production
engines, in-use testing, defect reporting, and recall.
(d) The engines must be labeled as described in Sec. 1036.135,
with the following statement instead of the one specified in Sec.
1036.135(c)(8): ``This engine conforms to alternative standards for
specialty vehicles under 40 CFR 1036.605.'' Engines certified under
this section may not have the label specified for nonroad engines in 40
CFR part 1039 or 1048 or any other label identifying them as nonroad
engines.
* * * * *
0
45. Amend Sec. 1036.615 by revising paragraph (b) to read as follows:
Sec. 1036.615 Engines with Rankine cycle waste heat recovery and
hybrid powertrains.
* * * * *
(b) Rankine engines. Test engines that include Rankine-cycle
exhaust energy recovery systems according to the procedures specified
in subpart F of this part unless we approve alternative procedures.
* * * * *
0
46. Amend Sec. 1036.701 by revising paragraph (k) to read as follows:
Sec. 1036.701 General provisions.
* * * * *
(k) Engine families you certify with a nonconformance penalty under
40 CFR part 1071, may not generate emission credits.
0
47. Amend Sec. 1036.705 by revising paragraph (b) to read as follows:
Sec. 1036.705 Generating and calculating emission credits.
* * * * *
(b) For each participating family, calculate positive or negative
emission credits relative to the otherwise applicable emission
standard. Calculate positive emission credits for a family that has an
FEL below the standard. Calculate negative emission credits for a
family that has an FEL above the standard. Sum your positive and
negative credits for the model year before rounding. Calculate emission
credits to the nearest megagram (Mg) for each family using the
following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.061
Where:
Std = the emission standard, in (mg NOX)/hp[middot]hr
that applies under subpart B of this part for engines not
participating in the ABT program of this subpart (the ``otherwise
applicable standard'').
FL = the engine family's FEL for NOX, in mg/
hp[middot]hr rounded to the same number of decimal places as the
emission standard.
CF = a transient cycle conversion factor (hp[middot]hr/mile),
calculated by dividing the total (integrated) horsepower-hour over
the applicable duty cycle by 6.3 miles for engines subject to spark-
ignition standards and 6.5 miles for engines subject to compression-
ignition standards. This represents the average work performed over
the duty cycle.
Volume = the number of engines eligible to participate in the
averaging, banking, and trading program within the given engine
family or subfamily during the model year, as described in paragraph
(c) of this section.
UL = the useful life for the standard that applies for a given
primary intended service class, in miles.
c = 10-9 for NOX.
Example for model year 2030 Heavy HDE generating NOX
credits:
Std = 35 mg/hp[middot]hr
FL = 20 mg/hp[middot]hr
CF = 9.78 hp[middot]hr/mile
Volume = 15,342
UL = 650,000 miles
c = 10-9
Emission credits = (35-20) [middot] 9.78 [middot] 15,342 [middot]
650,000 [middot] 10-9
Emission credits = 1,463 Mg
* * * * *
0
48. Amend Sec. 1036.801 by:
0
a. Revising the introductory text;
0
b. Removing the definition of ``Act'';
0
c. Adding definitions of ``Certified configuration'' and ``Clean Air
Act'' in alphabetical order;
0
d. Revising the definitions of ``Designated Compliance Officer'',
``Hybrid'', ``Manufacture'', and ''New motor vehicle engine''; and
0
e. Adding a definition of ``Useful life'' in alphabetical order.
The additions and revisions read as follows:
Sec. 1036.801 Definitions.
The following definitions apply to this part. The definitions apply
to all subparts unless we note otherwise. All undefined terms have the
meaning the Clean Air Act gives to them. The definitions follow:
* * * * *
Certified configuration means a specific engine configuration that
is named in the application for certification.
* * * * *
Clean Air Act means the Clean Air Act, as amended, 42 U.S.C. 7401-
7671q.
* * * * *
Designated Compliance Officer means one of the following:
(1) For engines subject to compression-ignition standards,
Designated Compliance Officer means Supervisor, Diesel Engine
Compliance Branch, U.S. Environmental Protection Agency, 2000
Traverwood Drive, Ann Arbor, MI 48105;
[email protected];www.epa.gov/ve-certification.
(2) For engines subject to spark-ignition standards, Designated
Compliance Officer means Supervisor, Gasoline Engine Compliance Branch,
U.S. Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor,
MI 48105; [email protected]; www.epa.gov/ve-certification.
* * * * *
Hybrid means relating to an engine or powertrain that includes a
Rechargeable Energy Storage System. Hybrid engines store and recover
energy in a way that is integral to the engine or otherwise upstream of
the vehicle's transmission. Examples of hybrid engines include engines
with hybrid components connected to the front end of the engine (P0),
connected to the crankshaft before the clutch (P1), or connected
between the clutch and the transmission where the clutch upstream of
the hybrid feature is in addition to the transmission clutch or
clutches (P2). Engine-based systems that recover kinetic energy to
power an electric heater in the aftertreatment are themselves not
sufficient to qualify as a hybrid engine. The provisions in this part
that apply for hybrid powertrains apply equally for hybrid engines,
except as specified. Note that certain provisions in this part treat
hybrid powertrains intended for vehicles that include regenerative
braking different than those intended for vehicles that do not include
regenerative braking. The definition of
[[Page 43252]]
hybrid includes plug-in hybrid powertrains.
* * * * *
Manufacture means the physical and engineering process of
designing, constructing, and assembling a heavy-duty engine or a heavy-
duty vehicle.
* * * * *
New motor vehicle engine has the meaning given in the Clean Air
Act. This generally means a motor vehicle engine meeting any of the
following:
(1) A motor vehicle engine for which the ultimate purchaser has
never received the equitable or legal title is a new motor vehicle
engine. This kind of engine might commonly be thought of as ``brand
new'' although a new motor vehicle engine may include previously used
parts. Under this definition, the engine is new from the time it is
produced until the ultimate purchaser receives the title or places it
into service, whichever comes first.
(2) An imported motor vehicle engine is a new motor vehicle engine
if it was originally built on or after January 1, 1970.
(3) Any motor vehicle engine installed in a new motor vehicle.
* * * * *
Useful life means the period during which a new engine is required
to comply with all applicable emission standards.
* * * * *
0
49. Amend Sec. 1036.810 by revising introductory text and paragraphs
(a) and (d)(4) to read as follows:
Sec. 1036.810 Incorporation by reference.
Certain material is incorporated by reference into this part with
the approval of the Director of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, EPA must publish a document in the Federal
Register and the material must be available to the public. All approved
incorporation by reference (IBR) material is available for inspection
at EPA and at the National Archives and Records Administration (NARA).
Contact EPA at: U.S. EPA, Air and Radiation Docket Center, WJC West
Building, Room 3334, 1301 Constitution Ave. NW, Washington, DC 20004;
www.epa.gov/dockets; (202) 202-1744. For information on inspecting this
material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from the following sources:
(a) ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA, 19428-2959; (877) 909-2786; www.astm.org.
(1) ASTM D975-24a, Standard Specification for Diesel Fuel, approved
August 1, 2024 (ASTM D975); IBR approved for Sec. 1036.415(c).
(2) ASTM D3588-98 (Reapproved 2017)e1, Standard Practice for
Calculating Heat Value, Compressibility Factor, and Relative Density of
Gaseous Fuels, approved April 1, 2017 (ASTM D3588); IBR approved for
Sec. 1036.550(b).
(3) ASTM D4809-25, Standard Test Method for Heat of Combustion of
Liquid Hydrocarbon Fuels by Bomb Calorimeter (Precision Method),
approved November 1, 2025 (ASTM D4809); IBR approved for Sec.
1036.550(b).
(4) ASTM D4814-25a, Standard Specification for Automotive Spark-
Ignition Engine Fuel, approved December 15, 2025 (ASTM D4814); IBR
approved for Sec. 1036.415(c).
(5) ASTM D7467-23, Standard Specification for Diesel Fuel Oil,
Biodiesel Blend (B6 to B20), approved October 1, 2023 (ASTM D7467); IBR
approved for Sec. 1036.415(c).
* * * * *
(d) * * *
(1) 2019 13 CCR 1968.2, Title 13. Motor Vehicles, Division 3. Air
Resources Board, Chapter 1. Motor Vehicle Pollution Control Devices,
Article 2. Approval of Motor Vehicle Pollution Control Devices (New
Vehicles), Sec. 1968.2. Malfunction and Diagnostic System
Requirements--2004 and Subsequent Model-Year Passenger Cars, Light-Duty
Trucks, and Medium-Duty Vehicles and Engines, operative October 3, 2019
``13 CCR 1968.2''; into Sec. Sec. 1036.110(b); 1036.111(f).
(3) 2019 13 CCR 1971.1, Title 13. Motor Vehicles, Division 3. Air
Resources Board, Chapter 1. Motor Vehicle Pollution Control Devices,
Article 2. Approval of Motor Vehicle Pollution Control Devices (New
Vehicles), Sec. 1971.1. On-Board Diagnostic System Requirements--2010
and Subsequent Model-Year Heavy-Duty Engines, operative October 3, 2019
``13 CCR 1971.1''; into Sec. Sec. 1036.110(b); 1036.111(f);
1036.150(v).
* * * * *
(4) 2019 13 CCR 1971.5, 13 CA ADC 1971.5: 2019 CA REG TEXT 504962
(NS), 13 CA ADC 1971.5. Enforcement of Malfunction and Diagnostic
System Requirements for 2010 and Subsequent Model-Year Heavy-Duty
Engines, operative October 3, 2019 ``13 CCR 1971.5''; into Sec.
1036.110(b), 1036.111(f).
* * * * *
0
50. Amend appendix B of part 1036 by revising footnote a of Table 1 in
paragraph (b) to read as follows:
Appendix B of Part 1036--Transient Duty Cycles
* * * * *
(b) * * *
Table 1 of Appendix B--Transient Test Interval for Spark-Ignition Engines and Powertrains Under Sec. 1036.512
----------------------------------------------------------------------------------------------------------------
Engine testing Powertrain testing
---------------------------------------------------------------------------------
Record (seconds) Normalized Road grade coefficients
revolutions per Normalized Vehicle speed --------------------------
minute (percent) torque (percent) (mi/hr) a b c
----------------------------------------------------------------------------------------------------------------
* * * * * * *
----------------------------------------------------------------------------------------------------------------
\a\ Minimum operator demand.
0
51. Amend appendix B of part 1036 by revising footnote a of Table 2 in
paragraph (c) to read as follows:
(c) * * *
[[Page 43253]]
Table 2 of Appendix B--Transient Test Interval for Compression-Ignition Engines and Powertrains Under Sec.
1036.512
----------------------------------------------------------------------------------------------------------------
Engine testing Powertrain testing
---------------------------------------------------------------------------------
Record (seconds) Normalized Road grade coefficients
revolutions per Normalized Vehicle speed --------------------------
minute (percent) torque (percent) (mi/hr) a b c
----------------------------------------------------------------------------------------------------------------
* * * * * * *
----------------------------------------------------------------------------------------------------------------
\a\ Minimum operator demand.
0
52. Amend appendix B of part 1036 by revising footnote a of Table 3 in
paragraph (d) to read as follows:
(d) * * *
Table 3 of Appendix B--Transient Duty Cycle for Compression-Ignition Engines and Powertrains Under Sec.
1036.514
----------------------------------------------------------------------------------------------------------------
Engine testing Powertrain testing
---------------------------------------------------------------------------------
Record (seconds) Normalized Road grade coefficients
revolutions per Normalized Vehicle speed --------------------------
minute (percent) torque (percent) (mi/hr) a b c
----------------------------------------------------------------------------------------------------------------
* * * * * * *
----------------------------------------------------------------------------------------------------------------
\a\ Minimum operator demand.
PART 1037--CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES
0
53. The authority citation for part 1037 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
54. Amend Sec. 1037.135 by revising paragraph (e) to read as follows:
Sec. 1037.135 Labeling.
* * * * *
(e) You may ask us to approve modified labeling requirements in
this part 1037 if you show that it is necessary or appropriate. We will
approve your request if your alternative label is consistent with the
requirements of this part.
0
55. Amend Sec. 1037.205 by revising paragraph (e) to read as follows:
Sec. 1037.205 What must I include in my application?
* * * * *
(e) Describe any test equipment and procedures that you used,
including any special or alternative test procedures you used (see
Sec. 1037.501). Include information describing the procedures you used
to determine CdA values as specified in Sec. Sec. 1037.525
and 1037.527. Describe which type of data you are using for engine fuel
maps (see 40 CFR 1036.505).
* * * * *
0
56. Amend Sec. 1037.235 by revising paragraph (f) to read as follows:
Sec. 1037.235 Testing requirements for certification.
* * * * *
(f) If you use an alternative test procedure under 40 CFR 1065.10
and later testing shows that such testing does not produce results that
are equivalent to the procedures specified in subpart F of this part,
we may reject data you generated using the alternative procedure.
* * * * *
0
57. Amend Sec. 1037.501 by revising paragraph (e) to read as follows:
Sec. 1037.501 General testing and modeling provisions.
* * * * *
(e) You may use special or alternative procedures as specified in
40 CFR 1065.10.
* * * * *
0
58. Amend Sec. 1037.510 by revising paragraph (c)(3) to read as
follows:
Sec. 1037.510 Duty-cycle exhaust testing.
* * * * *
(c) * * *
(3) Table 1 to this paragraph (c)(3) follows:
Table 1 to Paragraph (c)(3) of Sec. 1037.510--Weighting Factors for Duty Cycles
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance-weighted Time-weighted \a\ Average speed
------------------------------------------------------------------------------------------------ during non-
55 mi/hr 65 mi/hr Parked idle idle cycles
Transient (%) cruise (%) cruise (%) Drive idle (%) (%) Non-idle (%) (mi/hr) \b\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Class 7 All Cabs........................ 19 17 64 .............. .............. .............. ..............
Class 8 Day Cabs........................ 19 17 64 .............. .............. .............. ..............
Class 8 Sleeper Cabs.................... 5 9 86 .............. .............. .............. ..............
Heavy-haul Tractors..................... 19 17 64 .............. .............. .............. ..............
Vocational--Regional.................... 20 24 56 0 25 75 38.41
Vocational--Multi-Purpose (2b-7)........ 54 29 17 17 25 58 23.18
[[Page 43254]]
Vocational--Multi-Purpose (8)........... 54 23 23 17 25 58 23.27
Vocational--Urban (2b-7)................ 92 8 0 15 25 60 16.25
Vocational--Urban (8)................... 90 10 0 15 25 60 16.51
Vocational with conventional powertrain 42 21 37 .............. .............. .............. ..............
(Phase 1 only).........................
Vocational Hybrid Vehicles (Phase 1 75 9 16 .............. .............. .............. ..............
only)..................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Note that these drive idle and non-idle weighting factors do not reflect additional drive idle that occurs during the transient cycle. The transient
cycle does not include any parked idle.
\b\ These values apply even for vehicles not following the specified speed traces.
* * * * *
0
59. Amend Sec. 1037.520 by revising paragraphs (e)(2) and (4) and (n)
to read as follows:
Sec. 1037.520 Modeling CO2 emissions to show that vehicles comply
with fuel consumption standards.
* * * * *
(e) * * *
(2) Weight reduction inputs for tractor components other than
wheels are specified in the following table:
Table 7 to Sec. 1037.520--Nonwheel-Related Weight Reductions From Alternative Materials for Tractors
[Pounds]
----------------------------------------------------------------------------------------------------------------
High-strength
Weight reduction technologies Aluminum steel Thermoplastic
----------------------------------------------------------------------------------------------------------------
Door............................................................ 20 6 ..............
Roof............................................................ 60 18 ..............
Cab rear wall................................................... 49 16 ..............
Cab floor....................................................... 56 18 ..............
Hood Support Structure System................................... 15 3 ..............
Hood and Front Fender........................................... .............. .............. 65
Day Cab Roof Fairing............................................ .............. .............. 18
Sleeper Cab Roof Fairing........................................ 75 20 40
Aerodynamic Side Extender....................................... .............. .............. 10
Fairing Support Structure System................................ 35 6 ..............
Instrument Panel Support Structure.............................. 5 1 ..............
Brake Drums--Drive (set of 4)................................... 140 74 ..............
Brake Drums--Non Drive (set of 2)............................... 60 42 ..............
Frame Rails..................................................... 440 87 ..............
Crossmember--Cab................................................ 15 5 ..............
Crossmember--Suspension......................................... 25 6 ..............
Crossmember--Non Suspension (set of 3).......................... 15 5 ..............
Fifth Wheel..................................................... 100 25 ..............
Radiator Support................................................ 20 6 ..............
Fuel Tank Support Structure..................................... 40 12 ..............
Steps........................................................... 35 6 ..............
Bumper.......................................................... 33 10 ..............
Shackles........................................................ 10 3 ..............
Front Axle...................................................... 60 15 ..............
Suspension Brackets, Hangers.................................... 100 30 ..............
Transmission Case............................................... 50 12 ..............
Clutch Housing.................................................. 40 10 ..............
Fairing Support Structure System................................ 35 6 ..............
Drive Axle Hubs (set of 4)...................................... 80 20 ..............
Non Drive Hubs (set of 2)....................................... 40 5 ..............
Two-piece driveshaft............................................ 20 5 ..............
Transmission/Clutch Shift Levers................................ 20 4 ..............
----------------------------------------------------------------------------------------------------------------
* * * * *
(4) Apply vehicle weight inputs for changing technology
configurations as follows:
(i) For Class 8 tractors or for Class 8 vocational vehicles with a
permanent 6 x 2 axle configuration, apply a weight reduction input of
300 pounds. However, apply no weight reduction for coach buses
certified to custom-chassis standards under Sec. 1037.105(h).
(ii) For Class 8 tractors with 4 x 2 axle configuration, apply a
weight reduction input of 400 pounds.
[[Page 43255]]
(iii) For tractors with installed engines with displacement below
14.0 liters, apply a weight reduction of 300 pounds.
(iv) For tractors with single-piece driveshafts with a total length
greater than 86 inches, apply a weight reduction of 43 pounds for steel
driveshafts and 63 pounds for aluminum driveshafts.
* * * * *
(n) Other fuels. For fuels other than those identified in GEM,
perform the simulation by identifying the vehicle as being diesel-
fueled if the engine is subject to the compression-ignition standard,
or as being gasoline-fueled if the engine is subject to the spark-
ignition standards. Correct the engine or powertrain fuel map for mass-
specific net energy content as described in 40 CFR 1036.535(b).
0
60. Amend Sec. 1037.601 by revising paragraphs (a)(5) and (e) to read
as follows:
Sec. 1037.601 General compliance provisions.
(a) * * *
(5) The warranty-related prohibitions in section 203(a)(4) of the
Act (42 U.S.C. 7522(a)(4)) apply to manufacturers of new heavy-duty
highway vehicles in addition to the prohibitions described in 40 CFR
1068.101(b)(6). We may assess a civil penalty up to $44,539 for each
engine or vehicle in violation. Penalties apply as described in 40 CFR
1068.101.
* * * * *
(e) Under Sec. 1037.801, certain vehicles are considered to be new
vehicles when they are imported into the United States, even if they
have previously been used outside the country.
* * * * *
0
61. Amend Sec. 1037.605 by revising the section heading and paragraphs
(a) introductory text, (a)(4), (c), and (d)(1) to read as follows:
Sec. 1037.605 Installing engines certified to alternative standards
for specialty vehicles.
(a) General provisions. This section allows vehicle manufacturers
to introduce into U.S. commerce certain new motor vehicles using
engines certified to alternative emission standards specified in 40 CFR
1036.605 for motor vehicle engines used in specialty vehicles. You may
not install an engine certified to these alternative standards if there
is an engine certified to the full set of requirements of 40 CFR part
1036 that has the appropriate physical and performance characteristics
to power the vehicle. Note that, although these alternative emission
standards are mostly equivalent to standards that apply for nonroad
engines under 40 CFR part 1039 or 1048, they are specific to motor
vehicle engines. The provisions of this section apply for the following
types of specialty vehicles:
* * * * *
(4) Through model year 2030, vehicles with a hybrid powertrain in
which the engine provides energy only for the Rechargeable Energy
Storage System.
* * * * *
(c) Production limits. You may produce up to 200 of each type of
vehicle identified in paragraph (a) of this section in a given model
year. This includes vehicles produced by affiliated companies. If you
exceed this limit, the number of vehicles that exceed the limit for the
model year will not be covered by a valid certificate of conformity.
For the purpose of this paragraph (c), we will count all vehicles
labeled or otherwise identified as exempt under this section.
(d) * * *
(1) Vehicles qualifying under this section are subject to
evaporative and refueling emission standards as specified in Sec.
1037.103, but are exempt from the other requirements of this part,
except as specified in this section and in Sec. 1037.601.
* * * * *
0
62. Amend Sec. 1037.631 by revising paragraph (a) introductory text to
read as follows:
Sec. 1037.631 Exemption for vocational vehicles intended for off-road
use.
* * * * *
(a) Qualifying criteria. Vocational vehicles intended for off-road
use are exempt without request, subject to the provisions of this
section, if they are primarily designed to perform work off-road (such
as in oil fields, mining, forests, or construction sites), and they
meet at least one of the criteria of paragraph (a)(1) of this section
and at least one of the criteria of paragraph (a)(2) of this section.
See Sec. 1037.105(h) for alternative Phase 2 standards that apply for
vehicles meeting only one of these sets of criteria.
* * * * *
0
63. Amend Sec. 1037.635 by revising paragraph (b)(4) to read as
follows:
Sec. 1037.635 Glider kits and glider vehicles.
* * * * *
(b) * * *
(4) Note that alternative standards or requirements may apply under
Sec. 1037.150.
* * * * *
0
64. Amend Sec. 1037.660 by revising paragraph (c)(2) to read as
follows:
Sec. 1037.660 Idle-reduction technologies.
* * * * *
(c) * * *
(2) For AES systems designed to limit idling to a specific number
of hours less than 1,800 hours over any 12-month period, calculate an
adjusted AES input using the following equation, rounded to the nearest
0.1 g/ton-mile: AES Input = 5 g CO2/ton-mile x (1-(maximum
allowable number of idling hours per year/1,800 hours)). This is an
annual allowance that starts when the vehicle is new and resets every
12 months after that. Manufacturers may propose an alternative method
based on operating hours or miles instead of years.
* * * * *
0
65. Amend Sec. 1037.801 by revising the definitions of ``Date of
manufacture'', ``Designated Compliance Officer'', ``Fuel system'', and
``Hydrocarbon (HC)'' to read as follows:
Sec. 1037.801 Definitions.
* * * * *
Date of manufacture means the date on which the certifying vehicle
manufacturer completes its manufacturing operations, except as follows:
(1) Where the certificate holder is an engine manufacturer that
does not manufacture the chassis, the date of manufacture of the
vehicle is based on the date assembly of the vehicle is completed.
(2) We may approve an alternative date of manufacture based on the
date on which the certifying (or primary) manufacturer completes
assembly at the place of main assembly, consistent with the provisions
of Sec. 1037.601 and 49 CFR 567.4.
* * * * *
Designated Compliance Officer means one of the following:
(1) For compression-ignition engines, Designated Compliance Officer
means Supervisor, Diesel Engine Compliance Branch, U.S. Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
[email protected]; www.epa.gov/ve-certification.
(2) For spark-ignition engines, Designated Compliance Officer means
Supervisor, Gasoline Engine Compliance Branch, U.S. Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
[email protected]; www.epa.gov/ve-certification.
* * * * *
Fuel system means all components involved in transporting,
metering, and mixing the fuel from the fuel tank to the combustion
chamber(s), including the fuel tank, fuel pump, fuel filters, fuel
lines, carburetor or fuel-injection components, and all fuel-system
vents.
[[Page 43256]]
It also includes components for controlling evaporative and refueling
emissions, such as fuel caps, purge valves, and carbon canisters.
* * * * *
Hydrocarbon (HC) means the hydrocarbon group on which the emission
standards are based for each fuel type. For alcohol-fueled vehicles, HC
means nonmethane hydrocarbon equivalent (NMHCE) for exhaust emissions
and total hydrocarbon equivalent (THCE) for evaporative emissions. For
all other vehicles, HC means nonmethane hydrocarbon (NMHC) for exhaust
emissions and total hydrocarbon (THC) for evaporative and refueling
emissions.
* * * * *
0
66. Amend Sec. 1037.810 by revising paragraph (c)(7) to read as
follows:
Sec. 1037.810 Incorporation by reference.
* * * * *
(c) * * *
(7) SAE J2343 FEB2018, Recommended Practice for LNG Medium and
Heavy-Duty Powered Vehicles, Stabilized February 2018, (``SAE J2343'');
IBR approved for Sec. 1037.103(e).
* * * * *
PART 1039--CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD
COMPRESSION-IGNITION ENGINES
0
67. The authority citation for part 1039 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
68. Amend Sec. 1039.110 by revising paragraph (a) to read as follows:
Sec. 1039.110 Recording reductant use and other diagnostic functions.
(a) Engines equipped with SCR systems using a reductant other than
the engine's fuel must have a diagnostic system that monitors reductant
quality and tank levels and alert operators to the need to refill the
reductant tank before it is empty, or to replace the reductant if it
does not meet your concentration specifications. The diagnostic system
must include audible and visual signals as described in Sec. 1039.111.
You do not need to separately monitor reductant quality if your system
uses input from an exhaust NOX sensor (or other sensor) to
alert operators when reductant quality is inadequate. However, tank
level must be monitored in all cases.
* * * * *
0
69. Add Sec. 1039.111 to subpart B to read as follows:
Sec. 1039.111 Inducements related to SCR.
Engines using SCR to control emissions depend on a constant supply
of diesel exhaust fluid (DEF). This section describes how manufacturers
must design their engines to prompt operators to take appropriate
actions to ensure the SCR system is working properly. The requirements
of this section apply starting in model year 2029, though you may
comply with the requirements of this section in earlier model years.
(a) [Reserved]
(b) Inducement triggering conditions. Create strategies that
monitor for and trigger an inducement signal based on the following
conditions:
(1) Engine operation with no DEF.
(2) DEF with a urea concentration below 20 mass percent. You may
determine urea concentration based on direct measurement or based on a
surrogate value such as exhaust NOX concentration before and
after an SCR catalyst. Measurement may be limited to one time for each
occurrence of adding to the DEF tank. Use good engineering judgment to
determine urea concentration as soon as possible.
(3) Any signal indicating that a catalyst is missing.
(4) Open circuit faults related to the following: DEF tank level
sensor, DEF pump, DEF quality sensor, SCR wiring harness,
NOX sensors, DEF dosing valve, DEF tank heater, DEF tank
temperature sensor, and aftertreatment control module.
(c) Audible and visual signals. Design engines with audible and
visual signals corresponding to the inducement triggering conditions in
paragraph (b) of this section, subject to our approval, as follows:
(1) Audible signals must be sufficient to alert the operator to the
need for service. The tone must be active for 90 seconds with repeated
tones on one of the following schedules:
(i) For DEF supply, the tone must occur when the system detects the
triggering condition in paragraph (b)(1) of this section, when the
engine detects an empty DEF tank, 30 minutes after detecting an empty
DEF tank, 60 minutes after detecting an empty DEF tank, and then every
60 minutes until key-off.
(ii) For all conditions other than DEF supply, the tone must occur
when the system detects a triggering condition in paragraph (b)(2)
through (4) of this section, 30 minutes after detecting the triggering
condition, 90 minutes after detecting the triggering condition, and
then every 180 minutes until key-off.
(iii) If the triggering condition persists after keying off and on
again, engines must repeat the audible signal after key-on and
according to the time schedule described in paragraph (c)(1)(i) or (ii)
of this section.
(2) You may design your engines to suspend the audible signals in
paragraph (c)(1) of this section when ambient temperature is below -11
[deg]C. If the triggering condition persists, restart audible signals
at the same point in the schedule identified in paragraph (c)(1) of
this section when ambient temperature is above 0 [deg]C.
(3) Visual signals must be sufficient to alert the operator to the
need for service. Visual signals must be displayed until deactivation
as described in paragraph (e) of this section.
(d) Performance derates. You may rely on derating engine
performance for protecting aftertreatment systems and other engine
components from catastrophic damage, as long as derating is not based
only on an assessment of emission control performance (such as
evaluation of catalyst conversion efficiency).
(e) Deactivating inducements. Program the engine to deactivate
inducements as follows:
(1) Evaluate whether the detected inducement triggering condition
continues to apply. Deactivate inducements if the engine confirms that
the detected inducement triggering condition is resolved.
(2) If your system allows for remotely deactivating inducement
triggering codes, do not limit this capability to proprietary
scantools.
0
70. Amend Sec. 1039.115 by revising paragraph (e) and adding paragraph
(h) to read as follows:
Sec. 1039.115 What other requirements apply?
* * * * *
(e) Adjustable parameters. Engines that have adjustable parameters
must meet all the requirements of this part for any adjustment in the
practically adjustable range.
(1) We may require that you set adjustable parameters to any
specification within the practically adjustable range during any
testing, including certification testing, selective enforcement
auditing, or in-use testing.
(2) General provisions for adjustable parameters apply as specified
in 40 CFR 1068.50.
(3) DEF supply and DEF quality are adjustable parameters. The
practically adjustable range includes any amount of DEF for which the
engine's diagnostic system does not trigger inducement provisions under
Sec. 1036.111.
* * * * *
[[Page 43257]]
(h) The following additional requirements apply for engines with
SCR:
(1) Diesel exhaust fluid tanks must be sized to require refilling
no more frequently than the vehicle operator will need to refill the
fuel tank, even for worst-case assumptions related to fuel efficiency
and refueling volumes.
(2) Design engines to respond to varying DEF quality with
compensation algorithms that varies DEF injection to maintain
NOX emission control that is comparable to operation with
DEF conforming to the specifications referenced in the definition of
``diesel exhaust fluid'' in Sec. 1039.801, subject to the limitations
of the emission control hardware.
(3) Design engines for DEF freeze protection by including a warming
system to thaw DEF to restore DEF flow into the exhaust system within
70 minutes after engine starting using the procedure described in 40
CFR 1036.560.
0
71. Amend Sec. 1039.125 by revising paragraph (a)(1) introductory text
to read as follows:
Sec. 1039.125 What maintenance instructions must I give to buyers?
* * * * *
(a) * * *
(1) You demonstrate that the maintenance is reasonably likely to be
done at the recommended intervals on in-use engines. We will accept DEF
replenishment as reasonably likely to occur if your engine meets the
specifications in Sec. 1039.111. We will accept other scheduled
maintenance as reasonably likely to occur if you satisfy any of the
following conditions:
* * * * *
0
72. Amend Sec. 1039.130 by revising paragraph (b)(3) to read as
follows:
Sec. 1039.130 What installation instructions must I give to equipment
manufacturers?
* * * * *
(b) * * *
(3) Describe the instructions needed to properly install the
exhaust system and any other components. Include instructions
consistent with the requirements of Sec. 1039.205(u). Also describe
how equipment manufacturers must install diesel exhaust fluid tanks
with sensors and equipment as needed to meet the requirements of
Sec. Sec. 1039.111 and 1039.115(h).
* * * * *
0
73. Amend Sec. 1039.205 by adding paragraph (b)(12) to read as
follows:
Sec. 1039.205 What must I include in my application?
* * * * *
(b) * * *
(12) For engines using SCR, describe the following design features:
(i) Audible and visual signals required under Sec. 1039.111(c).
(ii) Compensation algorithms required under Sec. 1039.115(h)(2).
* * * * *
0
74. Amend Sec. 1039.501 by revising paragraph (d) to read as follows:
Sec. 1039.501 How do I run a valid emission test?
* * * * *
(d) Use the fuels and engine fluids specified in Sec. 1039.104(e)
and 40 CFR part 1065 to perform valid tests.
(1) For service accumulation, use the test fuel or any commercially
available fuel that is representative of the fuel that in-use engines
will use.
(2) For diesel-fueled engines, use the appropriate diesel fuel
specified in 40 CFR part 1065 for emission testing. Unless we specify
otherwise, the appropriate diesel test fuel is the ultra low-sulfur
diesel fuel. If we allow you to use a test fuel with higher sulfur
levels, identify the test fuel in your application for certification
and ensure that the emission control information label is consistent
with your selection of the test fuel (see Sec. 1039.135(c)(9)). For
example, do not test with ultra low-sulfur diesel fuel if you intend to
label your engines to allow use of diesel fuel with sulfur
concentrations up to 500 ppm.
(3) For engines using selective catalytic reduction, use diesel
exhaust fluid that conforms to the specifications referenced in the
definition of ``diesel exhaust fluid'' in Sec. 1039.801.
* * * * *
PART 1065--ENGINE-TESTING PROCEDURES
0
75. The authority citation for part 1065 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
76. Amend Sec. 1065.1 by revising paragraph (e) to read as follows:
Sec. 1065.1 Applicability.
* * * * *
(e) Unless we specify otherwise, the terms ``procedures'' and
``test procedures'' in this part include all aspects of engine testing,
including the equipment specifications, calibrations, calculations, and
other protocols and procedural specifications needed to make required
measurements.
* * * * *
0
77. Amend Sec. 1065.2 by revising paragraph (c) to read as follows:
Sec. 1065.2 Submitting information to EPA under this part.
* * * * *
(c) We may void any certificates or approvals associated with a
submission of information if we find that you intentionally submitted
false, incomplete, or misleading information. For example, if we find
that you intentionally submitted incomplete information to mislead EPA
when requesting approval to use alternative test procedures, we may
void the certificates for all engine families certified based on
emission data collected using the alternative procedures. This
paragraph (c) would also apply if you ignore data from incomplete tests
or from repeat tests with higher emission results.
* * * * *
0
78. Amend Sec. 1065.10 by revising paragraphs (c) introductory text,
(c)(6), (c)(7) introductory text, and (c)(7)(iii); and removing
paragraph (d) to read as follows:
Sec. 1065.10 Other procedures.
* * * * *
(c) Exceptions. We may allow or require you to use procedures other
than those specified in this part in the following cases, which may
apply to laboratory testing, field testing, or both. We intend to
publicly announce when we allow or require such exceptions. If we
require you to request approval to use other procedures under this
paragraph (c), you may not use them until we approve your request. All
the test procedures noted here as exceptions to the specified
procedures are considered generically as ``other procedures.'' Note
that the terms ``special procedures'' and ``alternative procedures''
have specific meanings; ``special procedures'' are those allowed by
paragraph (c)(2) of this section and ``alternative procedures'' are
those allowed by paragraph (c)(7).
* * * * *
(6) During the 12 months following the effective date of any change
in the provisions of this part 1065 (and 40 CFR part 1066 for vehicle
testing), you may use data collected using procedures specified in the
previously applicable version of this part 1065 (and 40 CFR part 1066
for vehicle testing). This also applies for changes to test procedures
specified in the standard-setting part to the extent that these changes
are not related to new standards. This paragraph (c)(6) does not
restrict the use of carryover certification data otherwise allowed by
the standard-setting part. This paragraph (c)(6) also does not prevent
us from identifying an earlier
[[Page 43258]]
starting date for certain changes to test procedures.
(7) You may request to use alternative procedures that are
equivalent to the specified procedures, or procedures that are more
accurate or more precise than the specified procedures. We may perform
tests with your engines using either the approved alternative
procedures or the specified procedures. We may reject data you generate
using alternate procedures if later testing with the otherwise
specified procedures shows contradictory emission data. The following
provisions apply to requests for alternative procedures:
* * * * *
(iii) Notification. We may approve your request by telling you
directly, or we may issue guidance announcing our approval of a
specific alternative procedure, which would make additional requests
for approval unnecessary.
* * * * *
0
79. Revise Sec. 1065.12 to read as follows:
Sec. 1065.12 Approval of alternative procedures.
(a) To get approval for an alternative procedure under Sec.
1065.10(c), send the EPA Program Officer an initial written request
describing the alternative procedure and why you believe it is
equivalent to the specified procedure. Anyone may request alternative
procedure approval. This means that an individual engine manufacturer
may request to use an alternative procedure. This also means that an
instrument manufacturer may request to have an instrument, equipment,
or procedure approved as an alternative procedure to those specified in
this part. We may approve your request based on this information alone,
whether or not it includes all the information specified in this
section. Where we determine that your original submission does not
include enough information for us to determine that the alternative
procedure is equivalent to the specified procedure, we may ask you to
submit supplemental information showing that your alternative procedure
is consistently and reliably at least as accurate and repeatable as the
specified procedure.
(b) We may make our approval under this section conditional upon
meeting other requirements or specifications. We may limit our
approval, for example, to certain time frames, specific duty cycles, or
specific emission standards. Based upon any supplemental information we
receive after our initial approval, we may amend a previously approved
alternative procedure to extend, limit, or discontinue its use. We
intend to publicly announce alternative procedures that we approve.
(c) Although we will make every effort to approve only alternative
procedures that completely meet our requirements, we may revoke our
approval of an alternative procedure if new information shows that it
is significantly not equivalent to the specified procedure. If we do
this, we will grant time to switch to testing using an allowed
procedure, considering the following factors:
(1) The cost, difficulty, and availability to switch to a procedure
that we allow.
(2) The degree to which the alternative procedure affects your
ability to show that your engines comply with all applicable emission
standards.
(3) Any relevant factors considered in our initial approval.
(d) If we do not approve your proposed alternative procedure based
on the information in your initial request, we may ask you to send
additional information to fully evaluate your request. While we
consider the information specified in this paragraph (d) and the
statistical criteria of paragraph (e) of this section to be sufficient
to demonstrate equivalence, it may not be necessary to include all the
information or meet the specified statistical criteria. For example,
systems that do not meet the statistical criteria in paragraph (e) of
this section because they have a small bias toward high emission
results could be approved since they would not adversely affect your
ability to demonstrate compliance with applicable standards.
(1) Theoretical basis. Give a brief technical description
explaining why you believe the proposed alternative procedure should
result in emission measurements equivalent to those using the specified
procedure. You may include equations, figures, and references. You
should consider the full range of parameters that may affect
equivalence. For example, for a request to use a different
NOX measurement procedure, you should theoretically relate
the alternative detection principle to the specified detection
principle over the expected concentration ranges for NO,
NO2, and interference species. For a request to use a
different PM measurement procedure, you should explain the principles
by which the alternative procedure quantifies particulate mass
similarly to the specified procedures.
(2) Technical description. Describe briefly any hardware or
software needed to perform the alternative procedure. You may include
dimensioned drawings, flowcharts, schematics, and component
specifications. Explain any necessary calculations or other data
manipulation.
(3) Procedure execution. Describe briefly how to perform the
alternative procedure and recommend a level of training an operator
should have to achieve acceptable results. Summarize the installation,
calibration, operation, and maintenance procedures in a step-by-step
format. Describe how any calibration is performed using NIST-traceable
standards or other similar standards we approve. Calibration must be
specified by using known quantities and must not be specified as a
comparison with other allowed procedures.
(4) Data-collection techniques. Compare measured emission results
using the proposed alternative procedure and the specified procedure,
as follows:
(i) Both procedures must be calibrated independently to NIST-
traceable standards or to other similar standards we approve.
(ii) Include measured emission results from all applicable duty
cycles. Measured emission results should show that the test engine
meets all applicable emission standards according to specified
procedures.
(iii) Use statistical methods to evaluate the emission
measurements, such as those described in paragraph (e) of this section.
(e) Absent any other directions from us, use a t-test and an F-test
calculated according to Sec. 1065.602 to evaluate whether your
proposed alternative procedure is equivalent to the specified
procedure. We may give you specific directions regarding methods for
statistical analysis, or we may approve other methods that you propose.
Such alternative methods may be more or less stringent than those
specified in this paragraph (e). In determining the appropriate
statistical criteria, we will consider the repeatability of
measurements made with the reference procedure. For example, less
stringent statistical criteria may be appropriate for measuring
emission levels being so low that they adversely affect the
repeatability of reference measurements. We recommend that you consult
a statistician if you are unfamiliar with these statistical tests.
Perform the tests as follows:
(1) Repeat measurements for all applicable duty cycles at least
seven times for each procedure. You may use laboratory duty cycles to
evaluate field-testing procedures. Be sure to include all available
results to evaluate the precision and accuracy of the proposed
[[Page 43259]]
alternative procedure, as described in Sec. 1065.2.
(2) Demonstrate the accuracy of the proposed alternative procedure
by showing that it passes a two-sided t-test. Use an unpaired t-test,
unless you show that a paired t-test is appropriate under both of the
following provisions:
(i) For paired data, the population of the paired differences from
which you sampled paired differences must be independent. That is, the
probability of any given value of one paired difference is unchanged by
knowledge of the value of another paired difference. For example, your
paired data would violate this requirement if your series of paired
differences showed a distinct increase or decrease that was dependent
on the time at which they were sampled.
(ii) For paired data, the population of paired differences from
which you sampled the paired differences must have a normal (i.e.,
Gaussian) distribution. If the population of paired difference is not
normally distributed, consult a statistician for a more appropriate
statistical test, which may include transforming the data with a
mathematical function or using some kind of non-parametric test.
(3) Show that t is less than the critical t value,
tcrit, tabulated in Sec. 1065.602, for the following
confidence intervals:
(i) 90% for a proposed alternative procedure for laboratory
testing.
(ii) 95% for a proposed alternative procedure for field testing.
(4) Demonstrate the precision of the proposed alternative procedure
by showing that it passes an F-test. Use a set of at least seven
samples from the reference procedure and a set of at least seven
samples from the alternative procedure to perform an F-test. The sets
must meet the following requirements:
(i) Within each set, the values must be independent. That is, the
probability of any given value in a set must be unchanged by knowledge
of another value in that set. For example, your data would violate this
requirement if a set showed a distinct increase or decrease that was
dependent upon the time at which they were sampled.
(ii) For each set, the population of values from which you sampled
must have a normal (i.e., Gaussian) distribution. If the population of
values is not normally distributed, consult a statistician for a more
appropriate statistical test, which may include transforming the data
with a mathematical function or using some kind of non-parametric test.
(iii) The two sets must be independent of each other. That is, the
probability of any given value in one set must be unchanged by
knowledge of another value in the other set. For example, your data
would violate this requirement if one value in a set showed a distinct
increase or decrease that was dependent upon a value in the other set.
Note that a trend of emission changes from an engine would not violate
this requirement.
(iv) If you collect paired data for the paired t-test in paragraph
(e)(2) in this section, use caution when selecting sets from paired
data for the F-test. If you do this, select sets that do not mask the
precision of the measurement procedure. We recommend selecting such
sets only from data collected using the same engine, measurement
instruments, and test cycle.
(5) Show that F is less than the critical F value,
Fcrit, tabulated in Sec. 1065.602. If you have several F-
test results from several sets of data, show that the mean F-test value
is less than the mean critical F value for all the sets. Evaluate
Fcrit, based on the following confidence intervals:
(i) 90% for a proposed alternative procedure for laboratory
testing.
(ii) 95% for a proposed alternative procedure for field testing.
0
80. Amend Sec. 1065.140 by adding paragraph (b)(2)(vi) to read as
follows:
Sec. 1065.140 Dilution for gaseous and PM constituents.
* * * * *
(b) * * *
(2) * * *
(vi) You may use the provisions in 40 CFR 1066.110(b)(2)(i).
* * * * *
0
81. Amend Sec. 1065.201 by revising paragraph (b) to read as follows:
Sec. 1065.201 Overview and general provisions.
* * * * *
(b) Instrument types. You may use any of the specified instruments
as described in this subpart to perform emission tests. If you want to
use one of these instruments in a way that is not specified in this
subpart, or if you want to use a different instrument, you must first
get us to approve your alternative procedure under Sec. 1065.10. Where
we specify more than one instrument for a particular measurement, we
may identify which instrument serves as the reference for comparing
with an alternative procedure. You may generally use instruments with
compensation algorithms that are functions of other gaseous
measurements and the known or assumed fuel properties for the test
fuel. The target value for any compensation algorithm is 0% (that is,
no bias high and no bias low), regardless of the uncompensated signal's
bias.
* * * * *
0
82. Amend Sec. 1065.225 by revising paragraph (a) to read as follows:
Sec. 1065.225 Intake-air flow meter.
(a) Application. You may use intake-air flow meters in combination
with a chemical balance of fuel, DEF, intake air, and raw exhaust to
calculate raw exhaust flow as described in Sec. 1065.655(f) and (g).
You may also use intake-air flow meters to determine the amount of
intake air input for performing carbon balance error verification in
Sec. 1065.543 and to calculate the measured amount of intake air,
nint, as described in Sec. 1065.643. The following
provisions apply for using intake-air flow meters:
(1) Use the actual value of calculated raw exhaust in the following
cases:
(i) For multiplying raw exhaust flow rate with continuously sampled
concentrations.
(ii) For multiplying total raw exhaust flow with batch-sampled
concentrations.
(iii) For verifying minimum dilution ratio for PM batch sampling as
described in Sec. 1065.546.
(iv) For calculating the dilution air flow for background
correction as described in Sec. 1065.667.
(2) In the following cases, you may use an intake-air flow meter
signal that does not give the actual value of raw exhaust, as long as
it is linearly proportional to the exhaust flow rate's actual
calculated value:
(i) For feedback control of a proportional sampling system, such as
a partial-flow dilution system.
(ii) For multiplying with continuously sampled gas concentrations,
if the same signal is used in a chemical-balance calculation to
determine work from brake-specific fuel consumption and fuel consumed.
* * * * *
0
83. Amend Sec. 1065.248 by:
0
a. Adding an undesignated center heading ``CO AND CO2
MEASUREMENTS'' immediately before Sec. 1065.248 section heading; and
0
b. After paragraph (b), removing the undesignated text ``CO AND
CO2 MEASUREMENTS''.
0
84. Amend Sec. 1065.257 by revising paragraph (d) to read as follows:
Sec. 1065.257 H2O measurement devices.
* * * * *
(d) Interference verification. Certain compounds can interfere with
FTIR and laser infrared analyzers by causing a response similar to
water. Perform
[[Page 43260]]
interference verification for the following interference species:
(1) Perform CO2 interference verification for FTIR
analyzers using the procedures of Sec. 1065.357. Use good engineering
judgment to determine other interference species for FTIR analyzers
when performing interference verification. Consider at least CO, NO,
C2H4, and C7H8. Perform
interference verifications using the procedures of Sec. 1065.357,
replacing occurrences of CO2 with each targeted interference
species. Determine interference species under this paragraph (d)(1)
that are appropriate for each H2O infrared absorption band,
or you may identify the interference species based on the instrument
manufacturer's recommendations.
(2) Perform interference verification for laser infrared analyzers
using the procedures of Sec. 1065.358. Use good engineering judgment
to determine interference species for laser infrared analyzers. Note
that interference species are dependent on the H2O infrared
absorption band chosen by the instrument manufacturer. For each
analyzer determine the H2O infrared absorption band.
Determine interference species under this paragraph (d)(2) that are
appropriate for each H2O infrared absorption band, or you
may identify the interference species based on the instrument
manufacturer's recommendations.
0
85. Remove the undesignated center heading ``HYDROCARBON MEASUREMENTS''
immediately before Sec. 1065.260 section heading.
0
86. Amend Sec. 1065.267 by revising paragraph (a) to read as follows:
Sec. 1065.267 Gas chromatograph with a flame ionization detector.
(a) Application. You may use a gas chromatograph with a flame
ionization detector (GC-FID) to measure CH4 and
C2H6 concentrations of diluted exhaust for batch
sampling. While you may also use a nonmethane cutter to measure
CH4, as described in Sec. 1065.265, use a reference
procedure based on a gas chromatograph for comparison with any proposed
alternative measurement procedure under Sec. 1065.10.
* * * * *
0
87. Amend Sec. 1065.270 by revising paragraph (a) to read as follows:
Sec. 1065.270 Chemiluminescent NOX analyzer.
(a) Application. You may use a chemiluminescent detector (CLD) to
measure NOX concentration in raw or diluted exhaust for
batch or continuous sampling. We generally accept a CLD for
NOX measurement, even though it measures only NO and
NO2, when coupled with an NO2-to-NO converter,
since conventional engines and aftertreatment systems do not emit
significant amounts of NOX species other than NO and
NO2. Measure other NOX species if required by the
standard-setting part. While you may also use other instruments to
measure NOX, as described in Sec. 1065.272, use a reference
procedure based on a chemiluminescent detector for comparison with any
proposed alternative measurement procedure under Sec. 1065.10.
* * * * *
0
88. Amend Sec. 1065.290 by revising paragraph (b) to read as follows:
Sec. 1065.290 PM gravimetric balance.
* * * * *
(b) Component requirements. We recommend that you use a balance
that meets the specifications in Table 1 of Sec. 1065.205. Note that
your balance-based system must meet the linearity verification in Sec.
1065.307. If the balance uses internal calibration weights for routine
spanning and the weights do not meet the specifications in Sec.
1065.790, the weights must be verified independently with external
calibration weights meeting the requirements of Sec. 1065.790. While
you may also use an inertial balance to measure PM, as described in
Sec. 1065.295, use a reference procedure based on a gravimetric
balance for comparison with any proposed alternative measurement
procedure under Sec. 1065.10.
* * * * *
0
89. Revise and republish Sec. 1065.303 to read as follows:
Sec. 1065.303 Summary of required calibration and verifications.
The following table summarizes the required and recommended
calibrations and verifications described in this subpart and indicates
when these have to be performed:
Table 1 of Sec. 1065.303--Summary of Required Calibration and
Verifications
------------------------------------------------------------------------
Type of calibration or
verification Minimum frequency \a\
------------------------------------------------------------------------
Sec. 1065.305: Accuracy, Accuracy: Not required, but
repeatability and noise. recommended for initial
installation.
Repeatability: Not required, but
recommended for initial
installation.
Noise: Not required, but recommended
for initial installation.
Sec. 1065.307: Linearity Speed: Upon initial installation,
verification. within 370 days before testing and
after major maintenance.
Torque: Upon initial installation,
within 370 days before testing and
after major maintenance. In the
case of torque measurement
transducers and systems that are
shipped off-site for linearity
verification, the linearity
verification is required within 370
days before testing, plus up to an
additional 185 days before testing
to store and transport calibrated
equipment that is stored in a
controlled environment.
Electrical power, current, and
voltage: Upon initial installation,
within 370 days before testing and
after major maintenance.\b\
Fuel mass flow rate: Upon initial
installation, within 370 days
before testing, and after major
maintenance.
Fuel mass scale: Upon initial
installation, within 370 days
before testing, and after major
maintenance.
DEF mass flow rate: Upon initial
installation, within 370 days
before testing, and after major
maintenance.\c\
DEF mass scale: Upon initial
installation, within 370 days
before testing, and after major
maintenance.
Intake-air, dilution air, diluted
exhaust, and batch sampler flow
rates: Upon initial installation,
within 370 days before testing and
after major maintenance.\d\
Raw exhaust flow rate: Upon initial
installation, within 185 days
before testing and after major
maintenance.\d\
Gas dividers: Upon initial
installation, within 370 days
before testing, and after major
maintenance.
[[Page 43261]]
Gas analyzers (unless otherwise
noted): Upon initial installation,
within 35 days before testing and
after major maintenance.
FTIR, HO laser infrared analyzers,
and photoacoustic analyzers: Upon
initial installation, within 370
days before testing and after major
maintenance.
GC-ECD: Upon initial installation
and after major maintenance.
PM balance: Upon initial
installation, within 370 days
before testing and after major
maintenance.
Pressure, temperature, and dewpoint:
Upon initial installation, within
370 days before testing and after
major maintenance.
Sec. 1065.308: Continuous gas Upon initial installation or after
analyzer system response and system modification that would
updating-recording verification-- affect response.
for gas analyzers not
continuously compensated for
other gas species.
Sec. 1065.309: Continuous gas Upon initial installation or after
analyzer system-response and system modification that would
updating-recording verification-- affect response.
for gas analyzers continuously
compensated for other gas species.
Sec. 1065.310: Torque........... Upon initial installation and after
major maintenance.
Sec. 1065.315: Pressure, Upon initial installation and after
temperature, dewpoint. major maintenance.
Sec. 1065.320: Fuel flow........ Upon initial installation and after
major maintenance.
Sec. 1065.325: Intake flow...... Upon initial installation and after
major maintenance.
Sec. 1065.330: Exhaust flow..... Upon initial installation and after
major maintenance.
Sec. 1065.340: Diluted exhaust Upon initial installation and after
flow (CVS). major maintenance.
Sec. 1065.341: CVS and PFD flow Upon initial installation, within 35
verification (propane check). days before testing, and after
major maintenance.\e\
Sec. 1065.342 Sample dryer For thermal chillers: upon
verification. installation and after major
maintenance.
For osmotic membranes; upon
installation, within 35 days of
testing, and after major
maintenance.
Sec. 1065.345: Vacuum leak...... For laboratory testing: upon initial
installation of the sampling
system, within 8 hours before the
start of the first test interval of
each duty-cycle sequence, and after
maintenance such as pre-filter
changes.
For field testing: after each
installation of the sampling system
on the vehicle, prior to the start
of the field test, and after
maintenance such as pre-filter
changes.
Sec. 1065.350: CO2 NDIR H2O Upon initial installation and after
interference. major maintenance.
Sec. 1065.355: CO NDIR CO2 and Upon initial installation and after
H2O interference. major maintenance.
Sec. 1065.357: H2O FTIR Upon initial installation and after
interference. major maintenance.
Sec. 1065.358: H2O LIA Upon initial installation and after
interference. major maintenance.
Sec. 1065.360: FID calibration.. Calibrate all FID analyzers: upon
THC FID optimization, and THC FID initial installation and after
verification. major maintenance.
Optimize and determine CH4 response
for THC FID analyzers: upon initial
installation and after major
maintenance.
Verify CH4 response for THC FID
analyzers: upon initial
installation, within 185 days
before testing, and after major
maintenance.
Verify C2H6 response for THC FID
analyzers if used for NMNEHC
determination: upon initial
installation, within 185 days
before testing, and after major
maintenance.
Sec. 1065.362: Raw exhaust FID For all FID analyzers: upon initial
O2 interference. installation, and after major
maintenance.
For THC FID analyzers: upon initial
installation, after major
maintenance, and after FID
optimization according to Sec.
1065.360.
Sec. 1065.365: Nonmethane cutter Upon initial installation, within
penetration. 185 days before testing, and after
major maintenance.
Sec. 1065.366: Interference Upon initial installation and after
verification for FTIR analyzers. major maintenance.
Sec. 1065.369: H2O, CO, and CO2 Upon initial installation and after
interference verification for major maintenance.
ethanol photoacoustic analyzers.
Sec. 1065.370: CLD CO2 and H2O Upon initial installation and after
quench. major maintenance.
Sec. 1065.372: NDUV HC and H2O Upon initial installation and after
interference. major maintenance.
Sec. 1065.375: N2O analyzer Upon initial installation and after
interference. major maintenance.
Sec. 1065.376: Chiller NO2 Upon initial installation and after
penetration. major maintenance.
Sec. 1065.377: Interference Upon initial installation and after
verification for NH3 analyzers. major maintenance.
Sec. 1065.378: NO2-to-NO Upon initial installation, within 35
converter conversion. days before testing, and after
major maintenance.
Sec. 1065.390: PM balance and Independent verification: upon
weighing. initial installation, within 370
days before testing, and after
major maintenance.
Zero, span, and reference sample
verifications: within 12 hours of
weighing, and after major
maintenance.
Sec. 1065.395: Inertial PM Independent verification: upon
balance and weighing. initial installation, within 370
days before testing, and after
major maintenance.
Other verifications: upon initial
installation and after major
maintenance.
------------------------------------------------------------------------
\a\ Perform calibrations and verifications more frequently than we
specify, according to measurement system manufacturer instructions and
good engineering judgment.
\b\ Perform linearity verification either for electrical power or for
current and voltage.
\c\ Linearity verification is not required if DEF flow rate comes
directly from the ECM signal as described in Sec. 1065.247(b).
\d\ Linearity verification is not required if the flow signal's accuracy
is verified by carbon balance error verification as described in Sec.
1065.307(e)(5) or a propane check as described in Sec. 1065.341.
\e\ CVS and PFD flow verification (propane check) is not required for
measurement systems verified by linearity verification as described in
Sec. 1065.307 or carbon balance error verification as described in
Sec. 1065.341(h).
[[Page 43262]]
0
90. Amend Sec. 1065.308 by revising paragraphs (b) and (g)
introductory text to read as follows:
Sec. 1065.308 Continuous gas analyzer system-response and updating-
recording verification--for gas analyzers not continuously compensated
for other gas species.
* * * * *
(b) Measurement principles. This test verifies that the updating
and recording frequencies match the overall system response to a rapid
change in the value of concentrations at the sample probe. Gas
analyzers and their sampling systems must be optimized such that their
overall response to a rapid change in concentration is updated and
recorded at an appropriate frequency to prevent loss of information.
This test also verifies that the measurement system meets a minimum
response time. You may use the results of this test to determine
transformation time, t50, for the purposes of time alignment
of continuous data in accordance with Sec. 1065.650(c)(2)(i). You may
also use an alternative procedure to determine t50 in
accordance with good engineering judgment. Note that any such procedure
for determining t50 must account for both transport delay
and analyzer response time.
* * * * *
(g) Optional procedure. Instead of using a three-way valve to
switch between zero and span gases, you may use a fast-acting two-way
valve to switch sampling between ambient air and span gas at the probe
inlet. For this alternative procedure, the following provisions apply:
* * * * *
0
91. Amend Sec. 1065.309 by revising paragraph (b) to read as follows:
Sec. 1065.309 Continuous gas analyzer system-response and updating-
recording verification--for gas analyzers continuously compensated for
other gas species.
* * * * *
(b) Measurement principles. This procedure verifies that the
updating and recording frequencies match the overall system response to
a rapid change in the value of concentrations at the sample probe. It
indirectly verifies the time-alignment and uniform response of all the
continuous gas detectors used to generate a continuously combined/
compensated concentration measurement signal. Gas analyzer systems must
be optimized such that their overall response to rapid change in
concentration is updated and recorded at an appropriate frequency to
prevent loss of information. This test also verifies that the
measurement system meets a minimum response time. For this procedure,
ensure that all compensation algorithms and humidity corrections are
turned on. You may use the results of this test to determine
transformation time, t50, for the purposes of time alignment
of continuous data in accordance with Sec. 1065.650(c)(2)(i). You may
also use an alternative procedure to determine t50
consistent with good engineering judgment. Note that any such procedure
for determining t50 must account for both transport delay
and analyzer response time.
* * * * *
0
92. Amend Sec. 1065.340 by revising paragraph (h)(5) to read as
follows:
Sec. 1065.340 Diluted exhaust flow (CVS) calibration.
* * * * *
(h) * * *
(5) Set the variable restrictor to its wide-open position. Instead
of a variable restrictor, you may alternatively vary the pressure
downstream of the CFV by varying blower speed or by introducing a
controlled leak. Note that some blowers have limitations on nonloaded
conditions.
* * * * *
0
93. Amend Sec. 1065.342 by revising paragraph (e) to read as follows:
Sec. 1065.342 Sample dryer verification.
* * * * *
(e) Alternative sample dryer verification procedure. The following
method may be used in place of the sample dryer verification procedure
in (d) of this section. If you use a humidity sensor for continuous
monitoring of dewpoint at the sample dryer outlet you may skip the
performance check in Sec. 1065.342(d), but you must make sure that the
dryer outlet humidity is at or below the minimum value used for quench,
interference, and compensation checks.
0
94. Add Sec. 1065.358 to subpart D immediately before the center
heading ``Hydrocarbon Measurements'' to read as follows:
Sec. 1065.358 Interference verification for H2O Laser
Infrared Analyzer.
(a) Scope and frequency. If you measure H2O using a
laser infrared analyzer, verify the amount of interference after
initial analyzer installation and after major maintenance.
(b) Measurement principles. Certain compounds can positively
interfere with analyzers by causing a response similar to
H2O. If the analyzer uses compensation algorithms that rely
on measurements of other gases to meet this interference verification,
a correct result depends on simultaneously conducting these other
measurements to test the compensation algorithms during the analyzer
interference verification.
(c) System requirements. A H2O laser infrared analyzer
must have a combined interference that is within (0.0 0.4)
mmol/mol, though we strongly recommend a lower interference that is
within (0.0 0.2) mmol/mol.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the H2O laser
infrared analyzer as you would before an emission test.
(2) Flow a multi-component span gas that incorporates the target
interference species and meets the specifications in Sec. 1065.750 at
the analyzer inlet. Use interference span gas concentrations that are
at least as high as the maximum expected during testing.
(3) Allow time for the analyzer response to stabilize.
Stabilization time may include time to purge the transfer line and
account for analyzer response.
(4) Record the analyzer output for 30 seconds while it measures the
sample's concentration. Calculate the arithmetic mean of this data.
When performed with all the gases simultaneously, this is the combined
interference.
(5) The analyzer meets the interference verification if the result
of paragraph (d)(4) of this section meets the tolerance in paragraph
(c) of this section.
(6) You may instead perform interference verification procedures
separately for individual interference species. The system requirement
specified in paragraph (c) of this section applies based on the sum of
the interference values from separate interference species. If the
concentration of any interference species used is higher than the
maximum levels expected during testing, you may scale down each
observed interference value by multiplying the observed interference
value by the ratio of the maximum expected concentration value to the
concentration in the span gas. The sum of the scaled interference
values must meet the tolerance for combined interference as specified
in paragraph (c) of this section.
0
95. Amend Sec. 1065.360 by revising paragraph (b) to read as follows:
Sec. 1065.360 FID optimization and verification.
* * * * *
(b) Calibration. Use good engineering judgment to develop a
calibration procedure, such as one based on the FID-analyzer
manufacturer's instructions and recommended
[[Page 43263]]
frequency for calibrating the FID. Alternatively, you may remove system
components for off-site calibration. For a FID that measures THC,
calibrate using C3H8 calibration gases that meet
the specifications of Sec. 1065.750. For a FID that measures
CH4, calibrate using CH4 calibration gases that
meet the specifications of Sec. 1065.750. We recommend FID analyzer
zero and span gases that contain approximately the flow-weighted mean
concentration of O2 expected during testing. If you use a
FID to measure CH4 downstream of a nonmethane cutter (NMC),
you may calibrate that FID using CH4 calibration gases with
the NMC. Regardless of the calibration gas composition, calibrate on a
carbon number basis of one (C1). For example, if you use a
C3H8 span gas of concentration 200 [mu]mol/mol,
span the FID to respond with a value of 600 [mu]mol/mol. As another
example, if you use a CH4 span gas with a concentration of
200 [mu]mol/mol, span the FID to respond with a value of 200 [mu]mol/
mol.
* * * * *
0
96. Amend Sec. 1065.390 by revising paragraph (d) introductory text to
read as follows:
Sec. 1065.390 PM balance verifications and weighing process
verification.
* * * * *
(d) Reference sample weighing. Verify all mass readings during a
weighing session by weighing reference PM sample media (e.g. filters)
before and after a weighing session. A weighing session may be as short
as desired, but no longer than 80 hours, and may include both pre-test
and post-test mass readings. We recommend that weighing sessions be
eight hours or less. Successive mass determinations of each reference
PM sample media (e.g., filter) must return the same value within 5 [micro]g or 10% of the net PM mass expected at the
standard (if known), whichever is higher. If successive reference PM
sample media (e.g. filter) weighing events fail this criterion,
invalidate all individual test media (e.g., filter) mass readings
occurring between the successive reference media (e.g., filter) mass
determinations. You may reweigh these media (e.g. filter) in another
weighing session. If you invalidate a pre-test media (e.g. filter) mass
determination, that test interval is void. Perform this verification as
follows:
* * * * *
0
97. Amend Sec. 1065.510 by revising paragraphs (f)(3)(iii) and (h) to
read as follows:
Sec. 1065.510 Engine mapping.
* * * * *
(f) * * *
(3) * * *
(iii) For electronically governed variable-speed engines, you may
use a declared warm high-idle speed for calculating the alternative
maximum test speed as specified in Sec. 1065.610.
* * * * *
(h) Other mapping procedures. You may use other mapping procedures
if you believe the procedures specified in this section are unsafe or
unrepresentative for your engine. Any alternative techniques you use
must satisfy the intent of the specified mapping procedures, which is
to determine the maximum available torque at all engine speeds that
occur during a duty cycle. Identify any deviations from this section's
mapping procedures when you submit data to us.
0
98. Amend Sec. 1065.514 by revising paragraph (b) to read as follows:
Sec. 1065.514 Cycle-validation criteria for operation over specified
duty cycles.
* * * * *
(b) Testing performed by manufacturers. Emission tests that meet
the specifications of paragraph (f) of this section satisfy the
standard-setting part's requirements for duty cycles. You may ask to
use a dynamometer or other laboratory equipment that cannot meet those
specifications. We will approve your request as long as using the
alternative equipment does not adversely affect your ability to show
compliance with the applicable emission standards.
* * * * *
0
99. Amend Sec. 1065.520 by revising paragraph (g)(9) to read as
follows:
Sec. 1065.520 Pre-test verification procedures and pre-test data
collection.
* * * * *
(g) * * *
(9) If corrective action does not resolve the deficiency, you may
request to use the contaminated system as an alternative procedure
under Sec. 1065.10.
0
100. Amend Sec. 1065.530 by:
0
a. Removing paragraph (b)(8);
0
b. Redesignating paragraphs (b)(9)-(12) as paragraphs (b)(8)-(11),
respectively; and
0
c. Revising paragraph (c).
The revision reads as follows:
Sec. 1065.530 Emission test sequence.
* * * * *
(c) Start and run each test interval as described in this paragraph
(c). The procedure varies depending on whether the test interval is
part of a discrete-mode cycle, and whether the test interval includes
engine starting. Note that the standard-setting part may apply
different requirements for running test intervals. For example, 40 CFR
part 1033 specifies a different way to perform discrete-mode testing.
(1) For steady-state discrete-mode duty cycles, start the duty
cycle with the engine warmed-up and running as described in Sec.
1065.501(c)(2)(i). Run each mode in the sequence specified in the
standard-setting part. This will require controlling engine speed,
engine load, or other operator demand settings as specified in the
standard-setting part. Simultaneously start continuous data recording
and batch sampling. We recommend that you stabilize the engine for at
least 5 minutes for each mode. Once sampling begins, sample
continuously for at least 1 minute. Note that longer sample times may
be needed for accurately measuring very low emission levels.
(2) For transient and steady-state ramped-modal duty cycles that do
not include engine starting, start the test interval with the engine
running as soon as practical after completing engine preconditioning.
Simultaneously start continuous data recording, batch sampling, and
execution of the duty cycle.
(3) If engine starting is part of the test interval, simultaneously
start continuous data recording and batch sampling before attempting to
start the engine. Initiate the sequence of points in the duty cycle
when the engine starts.
(4) For batch sampling systems, you may advance or delay the start
and end of sampling at the beginning and end of the test interval to
improve the accuracy of the batch sample, consistent with good
engineering judgment.
* * * * *
0
101. Amend Sec. 1065.550 by revising paragraphs (b)(2) introductory
text and (b)(3) to read as follows:
Sec. 1065.550 Gas analyzer range verification and drift verification.
* * * * *
(b) * * *
(2) Drift verification requires two sets of emission calculations.
For each set of calculations, include all the constituents in the drift
verification. Calculate one set using the data before drift correction
and calculate the other set after correcting all the data for drift
according to Sec. 1065.672. Note that for purposes of drift
verification, you must leave unaltered any negative emission values
over a given test interval (i.e., do not set them to zero). These
unaltered values are used when verifying either test interval values or
composite emission values over the entire duty cycle for drift. For
each constituent to be verified,
[[Page 43264]]
both sets of calculations must include the following:
* * * * *
(3) The duty cycle is verified for drift if you satisfy the
following criteria:
(i) For each regulated gaseous exhaust constituent, you must
satisfy one of the following:
(A) For each test interval of the duty cycle, the difference
between the uncorrected and the corrected emission values of the
regulated constituent must be within 4% of the uncorrected
value or the applicable emissions standard, whichever is greater.
Alternatively, the difference between the uncorrected and the corrected
emission mass (or mass rate) values of the regulated constituent must
be within 4% of the uncorrected value or the composite work
(or power) multiplied by the applicable emissions standard, whichever
is greater. For purposes of verifying each test interval, you may use
either the reference or actual composite work (or power).
(B) For each test interval of the duty cycle and for each mass
subcomponent of the regulated constituent, the difference between the
uncorrected and the corrected emission values must be within 4% of the uncorrected value. Alternatively, the difference
between the uncorrected and the corrected emissions mass (or mass rate)
values must be within 4% of the uncorrected value.
(C) For the entire duty cycle, the difference between the
uncorrected and the corrected composite emission values of the
regulated constituent must be within 4% of the uncorrected
value or applicable emission standard, whichever is greater.
(D) For the entire duty cycle and for each subcomponent of the
regulated constituent, the difference between the uncorrected and the
corrected composite emission values must be within 4% of
the uncorrected value.
(ii) Where no emission standard applies for CO2,
H2, O2, H2O, and NH3, you
must satisfy one of the following:
(A) For each test interval of the duty cycle, the difference
between the uncorrected and the corrected CO2,
H2, O2, H2O, or NH3 values
must be within 4% of the uncorrected value; or the
difference between the uncorrected and the corrected CO2,
H2, O2, H2O, or NH3 mass
(or mass rate) values must be within 4% of the uncorrected
value.
(B) For the entire duty cycle, the difference between the
uncorrected and the corrected composite CO2, H2,
O2, H2O, or NH3 values must be within
4% of the uncorrected value.
* * * * *
0
102. Amend Sec. 1065.610 by revising paragraph (a)(2) to read as
follows:
Sec. 1065.610 Duty cycle generation.
* * * * *
(a) * * *
(2) For engines with a high-speed governor that will be subject to
a reference duty cycle that specifies normalized speeds greater than
100%, calculate an alternative maximum test speed,
fntest,alt, as specified in this paragraph (a)(2). If
fntest,alt is less than the measured maximum test speed,
fntest, determined in paragraph (a)(1) of this section,
replace fntest with fntest,alt. In this case,
fntest,alt becomes the ``maximum test speed'' for that
engine for all duty cycles. Note that Sec. 1065.510 allows you to
apply an optional declared maximum test speed to the final measured
maximum test speed determined as an outcome of the comparison between
fntest, and fntest,alt in this paragraph (a)(2). Determine
fntest,alt as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.062
Where:
fntest,alt = alternative maximum test speed
fnhi,idle = warm high-idle speed
fnidle = warm idle speed
% speedmax = maximum normalized speed from duty cycle
Example:
fnhi,idle = 2200 r/min
fnidle = 800 r/min
% speedmax = 105% (Nonroad CI Transient Cycle) = 1.05
[GRAPHIC] [TIFF OMITTED] TP14JY26.063
fntest,alt = 2133 r/min
* * * * *
0
103. Amend Sec. 1065.640 by revising paragraphs (a), (c)(5)(iv), and
(d)(1) to read as follows:
Sec. 1065.640 Flow meter calibration calculations.
* * * * *
(a) Reference meter conversions. The calibration equations in this
section use molar flow rate, nref, as a reference quantity.
If your reference meter outputs a flow rate in a different quantity,
such as standard volume rate, Vstdref, actual volume rate,
Vactref, or mass rate, mref, convert your
reference meter output to a molar flow rate using the following
equations, noting that while values for volume rate, mass rate,
pressure, temperature, and molar mass may change during an emission
test, you should ensure that they are as constant as practical for each
individual set point during a flow meter calibration:
[GRAPHIC] [TIFF OMITTED] TP14JY26.064
Where:
nref = reference molar flow rate.
Vstdref = standard volume flow rate output by the
reference flow meter at a standard pressure and standard
temperature.
Vactref = actual volume flow rate output by the reference
flow meter.
mref = mass flow rate output by the reference flow meter.
pstd = standard pressure used by the reference flow
meter.
pact = actual pressure of the flow rate.
Tstd = standard temperature used by the reference flow
meter.
R = molar gas constant.
Mmix = molar mass of the flow rate.
Example 1:
Vstdref = 1000.00 ft3/min = 0.471948
m3/s
pstd = 29.9213 in Hg @32 [deg]F = 101.325 kPa = 101325 Pa =
101325 kg/(m[middot]s2)
Tstd = 68.0 [deg]F = 293.15 K
R = 8.314472 J/(mol[middot]K) = 8.314472 (m\2\[middot]kg)/
(s\2\[middot]mol[middot]K)
[GRAPHIC] [TIFF OMITTED] TP14JY26.065
nref = 19.619 mol/s
Example 2:
mref = 17.2683 kg/min = 287.805 g/s
Mmix = 28.7805 g/mol
[GRAPHIC] [TIFF OMITTED] TP14JY26.066
nref = 10.0000 mol/s
* * * * *
[[Page 43265]]
(c) * * *
(5) * * *
(iv) For diluted exhaust and dilution air, you may assume the molar
mass of the mixture, Mmix, is a function only of the amount
of water in the dilution air or calibration air, as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.067
Where:
Mair = molar mass of dry air.
xH2O = amount of H2O in the dilution air or
calibration air, determined as described in Sec. 1065.645.
MH2O = molar mass of water.
Example:
Mair = 28.96623 g/mol
xH2O = 0.0169 mol/mol
MH2O = 18.01528 g/mol
Mmix = 28.96623 [middot] (1-0.0169) + 18.01528 [middot]
0.0169
Mmix = 28.7812 g/mol
* * * * *
(d) * * *
(1) Calculate the Reynolds number, Re#, for each
reference molar flow rate, nref, using the throat diameter
of the venturi, dt. Because the dynamic viscosity, [micro],
is needed to compute Re#, you may use your own fluid
viscosity model to determine [micro] for your calibration gas (usually
air), using good engineering judgment. Alternatively, you may use the
Sutherland three-coefficient viscosity model to approximate [micro], as
shown in the following sample calculation for Re#:
[GRAPHIC] [TIFF OMITTED] TP14JY26.068
Where, using the Sutherland three-coefficient viscosity model as
captured in Table 4 of this section:
[GRAPHIC] [TIFF OMITTED] TP14JY26.069
Where:
[micro]0 = Sutherland reference viscosity.
T0 = Sutherland reference temperature.
S = Sutherland constant.
Table 4 of Sec. 1065.640--Sutherland Three-Coefficient Viscosity Model Parameters
----------------------------------------------------------------------------------------------------------------
[micro]0 T0 S Temperature range within 2% error \b\ limit \b\
Gas \a\ kg/ --------------------------------------------
(m[middot]s) K K K kPa
----------------------------------------------------------------------------------------------------------------
Air...................... 1.716[middot]1 273 111 170 to 1900................... <= 1800
0- 5
CO2...................... 1.370[middot]1 273 222 190 to 1700................... <= 3600
0- 5
H2O...................... 1.12[middot]10- 350 1064 360 to 1500................... <= 10000
5
O2....................... 1.919[middot]1 273 139 190 to 2000................... <= 2500
0- 5
N2....................... 1.663[middot]1 273 107 100 to 1500................... <= 1600
0- 5
----------------------------------------------------------------------------------------------------------------
\a\ Use tabulated parameters only for the pure gases, as listed. Do not combine parameters in calculations to
calculate viscosities of gas mixtures.
\b\ The model results are valid only for ambient conditions in the specified ranges.
Example:
[micro]0 = 1.716[middot]10-5 kg/(m[middot]s)
T0 = 273 K
S = 111 K
[GRAPHIC] [TIFF OMITTED] TP14JY26.070
[micro] = 1.838[middot]10-5 kg/(m[middot]s)
Mmix = 28.7812 g/mol = 0.0287812 kg/mol
nref = 57.625 mol/s
dt = 152.4 mm = 0.1524 m
Tin = 298.15 K
[GRAPHIC] [TIFF OMITTED] TP14JY26.071
[[Page 43266]]
Re # = 7.538[middot]10\5\
* * * * *
0
104. Amend Sec. 1065.642 by revising paragraphs (b) and (c) to read as
follows:
Sec. 1065.642 PDP, SSV, and CFV molar flow rate calculations.
* * * * *
(b) SSV molar flow rate. Calculate SSV molar flow rate, n, as
follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.072
Where:
Cd = discharge coefficient, as determined based on the
Cd versus Re# equation in Sec.
1065.640(d)(2).
Cf = flow coefficient, as determined in Sec.
1065.640(c)(3)(ii).
At = venturi throat cross-sectional area.
pin = static absolute pressure at the venturi inlet.
Z = compressibility factor.
Mmix = molar mass of gas mixture.
R = molar gas constant.
Tin = absolute temperature at the venturi inlet.
Example:
At = 0.01824 m\2\
pin = 99.132 kPa = 99132 Pa = 99132 kg/(m[middot]s\2\)
Z = 1
Mmix = 28.7812 g/mol = 0.0287812 kg/mol
R = 8.314472 J/(mol[middot]K) = 8.314472 (m\2\[middot]kg)/
(s\2\[middot]mol[middot]K)
Tin = 298.15 K
Re# = 7.232[middot]10\5\
[gamma] = 1.399
[beta] = 0.8
[Delta]p = 2.312 kPa
Using Eq. 1065.640-7:
rssv = 0.997
Using Eq. 1065.640-6:
Cf = 0.274
Using Eq. 1065.640-5:
Cd = 0.990
[GRAPHIC] [TIFF OMITTED] TP14JY26.073
n = 58.067 mol/s
(c) CFV molar flow rate. If you use multiple venturis and you
calibrate each venturi independently to determine a separate discharge
coefficient, Cd (or calibration coefficient, Kv),
for each venturi, calculate the individual molar flow rates through
each venturi and sum all their flow rates to determine CFV flow rate,
n. If you use multiple venturis and you calibrated venturis in
combination, calculate n using the sum of the active venturi throat
areas as At, the square root of the sum of the squares of
the active venturi throat diameters as dt, and the ratio of
the venturi throat to inlet diameters as the ratio of the square root
of the sum of the active venturi throat diameters (dt) to
the diameter of the common entrance to all the venturis (D).
(1) To calculate n through one venturi or one combination of
venturis, use its respective mean Cd and other constants you
determined according to Sec. 1065.640 and calculate n as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.074
Where:
Cf = flow coefficient, as determined in Sec.
1065.640(c)(3).
Example:
Cd = 0.985
Cf = 0.7219
At = 0.00456 m2
pin = 98.836 kPa = 98836 Pa = 98836 kg/(m[middot]s\2\)
Z = 1
Mmix = 28.7812 g/mol = 0.0287812 kg/mol
R = 8.314472 J/(mol[middot]K) = 8.314472 (m2[middot]kg)/
(s2[middot]mol[middot]K)
Tin = 378.15 K
[GRAPHIC] [TIFF OMITTED] TP14JY26.075
n = 33.689 mol/s
(2) To calculate the molar flow rate through one venturi or a
combination of venturis, you may use its respective mean,
Kv, and other constants you determined according to Sec.
1065.640 and calculate its molar flow rate n during an emission test.
Note that if you follow the permissible ranges of dilution air dewpoint
versus calibration air dewpoint in Table 3 of Sec. 1065.640, you may
set Mmix-cal and Mmix equal to 1. Calculate n as
follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.076
Where:
[GRAPHIC] [TIFF OMITTED] TP14JY26.077
Vstdref = standard volume flow rate output by the CFV CVS
flow meter at a standard pressure and standard temperature.
Tin-cal = venturi inlet temperature during calibration.
Pin-cal = venturi inlet pressure during calibration.
Mmix-cal = molar mass of gas mixture used during
calibration.
Mmix = molar mass of gas mixture during the emission test
calculated using Eq. 1065.640-9.
Example:
Vstdref = 0.4895 m3/s
Tin-cal = 302.52 K
Pin-cal = 99.654 kPa = 99654 Pa = 99654 kg/
(m[middot]s2)
pin = 98.836 kPa = 98836 Pa = 98836 kg/
(m[middot]s2)
pstd = 101.325 kPa = 101325 Pa = 101325 kg/
(m[middot]s2)
Mmix-cal = 28.9656 g/mol = 0.0289656 kg/mol
Mmix = 28.7812 g/mol = 0.0287812 kg/mol
Tin = 353.15 K
Tstd = 293.15 K
R = 8.314472 J/(mol[middot]K) = 8.314472 (m2[middot]kg)/
(s2[middot]mol[middot]K)
[[Page 43267]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.078
n = 16.456 mol/s
0
105. Amend Sec. 1065.643 by revising paragraph (b) introductory text
to read as follows:
Sec. 1065.643 Carbon balance error verification calculations.
* * * * *
(b) Intake air. Calculate the mass of carbon in the intake air,
mCair, for each test interval using one of the methods in
this paragraph (b). The methods are listed in order of preference. Use
the first method where all the inputs are available for your test
configuration. For methods that calculate mCair based on the
amount of CO2 per mole of intake air, we recommend measuring
intake air concentration, but you may calculate xCO2int
using Eq. 1065.655-10 and letting xCO2intdry = 428
[micro]mol/mol.
* * * * *
0
106. Amend Sec. 1065.650 by revising paragraphs (d)(6) and (e)(2) to
read as follows:
Sec. 1065.650 Emission calculations.
* * * * *
(d) * * *
(6) Set all power values to zero during idle periods with a
corresponding denormalized reference torque of 0 N[middot]m.
* * * * *
(e) * * *
(2) To calculate an engine's mean steady-state total power, P, add
the mean steady-state power from all the work paths described in Sec.
1065.210 that cross the system boundary including electrical power,
mechanical shaft power, and fluid pumping power. For all work paths,
except the engine's primary output shaft (crankshaft), the mean steady-
state power over the test interval is the integration of the net work
flow rate (power) out of the system boundary divided by the period of
the test interval. When power flows into the system boundary, the
power/work flow rate signal becomes negative; in this case, include
these negative power/work rate values in the integration to calculate
the mean power from that work path. Some work paths may result in a
negative mean power. Include negative mean power values from any work
path in the mean total power from the engine rather than setting these
values to zero. The rest of this paragraph (e)(2) describes how to
calculate the mean power from the engine's primary output shaft.
Calculate P using Eq. 1065.650-14, noting that P, fn, and T
refer to mean power, mean rotational shaft frequency, and mean torque
from the primary output shaft. Account for the power of simulated
accessories according to Sec. 1065.110 (reducing the mean primary
output shaft power or torque by the accessory power or torque). Set the
power to zero during actual motoring operation (negative feedback
torques), unless the engine was connected to one or more energy storage
devices. Examples of such energy storage devices include hybrid
powertrain batteries and hydraulic accumulators, like the ones denoted
``Acc.'' and ``Batt.'' as illustrated in Figure 1 of Sec. 1065.210.
Set the power to zero for modes with a zero reference load (0
N[middot]m reference torque or 0 kW reference power). Include power
during idle modes with simulated minimum torque or power.
[GRAPHIC] [TIFF OMITTED] TP14JY26.079
* * * * *
0
107. Amend Sec. 1065.655 by revising paragraphs (c)(3) and (e)(1)(i)
to read as follows:
Sec. 1065.655 Carbon-based chemical balances of fuel, DEF, intake
air, and exhaust.
* * * * *
(c) * * *
(3) Use the following symbols and subscripts in the equations for
performing the chemical balance calculations in this paragraph (c):
Table 1 of Sec. 1065.655--Symbols and Subscripts for Chemical Balance
Equations
------------------------------------------------------------------------
------------------------------------------------------------------------
xdil/exh..................... amount of dilution gas or excess air per
mole of exhaust.
xH2Oexh...................... amount of H2O in exhaust per mole of
exhaust.
xCcombdry.................... amount of carbon from fuel and any
injected fluids in the exhaust per mole
of dry exhaust.
xH2dry....................... amount of H2 in exhaust per amount of dry
exhaust.
KH2Ogas...................... water-gas reaction equilibrium
coefficient; you may use 3.5 or
calculate your own value using good
engineering judgment.
xH2Oexhdry................... amount of H2O in exhaust per dry mole of
dry exhaust.
xprod/intdry................. amount of dry stoichiometric products per
dry mole of intake air.
xdil/exhdry.................. amount of dilution gas and/or excess air
per mole of dry exhaust.
xint/exhdry.................. amount of intake air required to produce
actual combustion products per mole of
dry (raw or diluted) exhaust.
xraw/exhdry.................. amount of undiluted exhaust, without
excess air, per mole of dry (raw or
diluted) exhaust.
xO2int....................... amount of intake air O2 per mole of
intake air.
xCO2intdry................... amount of intake air CO2 per mole of dry
intake air; you may use xCO2intdry = 428
[micro]mol/mol, but we recommend
measuring the actual concentration in
the intake air.
xH2Ointdry................... amount of intake air H2O per mole of dry
intake air.
xCO2int...................... amount of intake air CO2 per mole of
intake air.
xCO2dil...................... amount of dilution gas CO2 per mole of
dilution gas.
xCO2dildry................... amount of dilution gas CO2 per mole of
dry dilution gas; if you use air as
diluent, you may use xCO2dildry = 428
[micro]mol/mol, but we recommend
measuring the actual concentration in
the intake air.
xH2Odildry................... amount of dilution gas H2O per mole of
dry dilution gas.
xH2Odil...................... amount of dilution gas H2O per mole of
dilution gas.
x[emission]meas.............. amount of measured emission in the sample
at the respective gas analyzer.
x[emission]dry............... amount of emission per dry mole of dry
sample.
[[Page 43268]]
xH2O[emission]meas........... amount of H2O in sample at emission-
detection location; measure or estimate
these values according to Sec.
1065.145(e)(2).
xH2Oint...................... amount of H2O in the intake air, based on
a humidity measurement of intake air.
[alpha]...................... atomic hydrogen-to-carbon ratio of the
fuel (or mixture of test fuels) and any
injected fluids.
[beta]....................... atomic oxygen-to-carbon ratio of the fuel
(or mixture of test fuels) and any
injected fluids.
[gamma]...................... atomic sulfur-to-carbon ratio of the fuel
(or mixture of test fuels) and any
injected fluids.
[delta]...................... atomic nitrogen-to-carbon ratio of the
fuel (or mixture of test fuels) and any
injected fluids.
------------------------------------------------------------------------
* * * * *
(e) * * *
(1) * * *
(i) Determine the carbon and hydrogen mass fractions according to
ASTM D5291 (incorporated by reference, see Sec. 1065.1010). When using
ASTM D5291 to determine carbon and hydrogen mass fractions of gasoline
(with or without blended ethanol), use good engineering judgment to
adapt the method as appropriate. This may include consulting with the
instrument manufacturer on how to test high-volatility fuels. Allow the
weight of volatile fuel samples to stabilize for 20 minutes before
starting the analysis; if the weight still drifts after 20 minutes,
prepare a new sample). Retest the sample if the carbon, hydrogen,
oxygen, sulfur, and nitrogen mass fractions do not add up to a total
mass of 100 0.5%; you may assume oxygen has a zero mass
contribution for this specification for diesel fuel and neat (E0)
gasoline. You may not normalize your mass fraction results to total
100%. You may also assume that sulfur and nitrogen have a zero mass
contribution for this specification for all fuels except residual fuel
blends.
* * * * *
0
108. Amend Sec. 1065.656 by revising entries for
``xCO2intdry'' and ``xCO2dildry'' in Table 1 to
paragraph (c)(3) to read as follows:
Sec. 1065.656 Hydrogen-based chemical balances of fuel, DEF, intake
air, and exhaust.
* * * * *
(c) * * *
(3) * * *
Table 1 to Paragraph (c)(3) of Sec. 1065.656--Symbols and Subscripts
for Chemical Balance Equations
------------------------------------------------------------------------
------------------------------------------------------------------------
* * * * * * *
xCO2intdry................... amount of intake air CO2 per mole of dry
intake air; you may use xCO2intdry = 428
[micro]mol/mol, but we recommend
measuring the actual concentration in
the intake air.
* * * * * * *
xCO2dildry................... Amount of dilution gas CO2 per mole of
dry dilution gas; if you use air as
diluent, you may use xCO2dildry = 428
[micro]mol/mol, but we recommend
measuring the actual concentration in
the dilution gas.
* * * * * * *
------------------------------------------------------------------------
* * * * *
0
109. Amend Sec. 1065.672 by revising paragraph (d)(7) to read as
follows:
Sec. 1065.672 Drift correction.
* * * * *
(d) * * *
(7) Usually the reference concentration of the zero gas, xrefzero,
is zero: xrefzero = 0 [micro]mol/mol. However, in some cases
you might know that xrefzero has a non-zero concentration.
For example, if you zero a CO2 analyzer using ambient air, you may use
the default ambient air concentration of CO2, which is 428
[micro]mol/mol. In this case, xrefzero = 428 [micro]mol/mol.
Note that when you zero an analyzer using a non-zero
xrefzero, you must set the analyzer to output the actual
xrefzero concentration. For example, if xrefzero
= 428 [micro]mol/mol, set the analyzer to output a value of 428
[micro]mol/mol when the zero gas is flowing to the analyzer.
0
110. Amend Sec. 1065.695 by revising paragraphs (a), (c)(1)
introductory text, and (c)(11)(ii) to read as follows:
Sec. 1065.695 Data requirements.
(a) To determine the information we require from engine tests,
refer to the standard-setting part and request from your EPA Program
Officer the format used to apply for certification or demonstrate
compliance. We may require different information for different
purposes, such as for certification applications, approval requests for
alternative procedures, selective enforcement audits, laboratory
audits, production-line test reports, and field-test reports.
* * * * *
(c) * * *
(1) What approved alternative procedures did you use? For example:
* * * * *
(11) * * *
(ii) Alternative fuel.
* * * * *
0
111. Amend Sec. 1065.701 by revising paragraphs (b) and (f) to read as
follows:
Sec. 1065.701 General requirements for test fuels.
* * * * *
(b) Fuels meeting alternative specifications. We may allow you to
use a different test fuel (such as California LEV III gasoline) if it
does not affect your ability to show that your engines would comply
with all applicable emission standards in this chapter using the test
fuel specified in this subpart.
* * * * *
(f) Service accumulation and field testing fuels. If we do not
specify a service-accumulation or field-testing fuel in the standard-
setting part, use an appropriate commercially available fuel such as
those meeting minimum specifications from the following table:
[[Page 43269]]
Table 1 of Sec. 1065.701--Examples of Service-Accumulation and Field-
Testing Fuels
------------------------------------------------------------------------
Reference
Fuel category Subcategory procedure
------------------------------------------------------------------------
Diesel........................ Light distillate and ASTM D975.
light blends with
residual.
Middle distillate..... ASTM D6985.
Biodiesel (B100)...... ASTM D6751.
Intermediate and residual fuel All................... See Sec.
1065.705.
Gasoline...................... Automotive gasoline... ASTM D4814.
Automotive gasoline ASTM D4814.
with ethanol
concentration up to
10 volume %.
Alcohol....................... Ethanol (E51-83)...... ASTM D5798.
Methanol (M70-M85).... ASTM D5797.
Aviation fuel................. Aviation gasoline..... ASTM D910.
Gas turbine........... ASTM D1655.
Jet B wide cut........ ASTM D6615.
Gas turbine fuel.............. General............... ASTM D2880.
------------------------------------------------------------------------
* * * * *
0
112. Amend Sec. 1065.715 by revising paragraph (b)(2) to read as
follows:
Sec. 1065.715 Natural gas.
* * * * *
(b) * * *
(2) You may use fuel meeting alternative specifications if the
standard-setting part allows it.
* * * * *
0
113. Amend Sec. 1065.720 by revising paragraph (b)(2) to read as
follows:
Sec. 1065.720 Liquefied petroleum gas.
* * * * *
(b) * * *
(2) You may use fuel meeting alternative specifications if the
standard-setting part allows it.
* * * * *
0
114. Amend Sec. 1065.750 by revising paragraph (a)(6) introductory
text to read as follows:
Sec. 1065.750 Analytical gases.
* * * * *
(a) * * *
(6) If you measure H2O using an FTIR or laser infrared
analyzer, generate H2O calibration gases with a humidity
generator using one of the options in this paragraph (a)(6). Use good
engineering judgment to prevent condensation in the transfer lines,
fittings, or valves from the humidity generator to the analyzer. Design
your system so the wall temperatures in the transfer lines, fittings,
and valves from the point where the mole fraction of H2O in
the humidified calibration gas, xH2Oref, is measured to the
analyzer are at a temperature of (110 to 202) [deg]C. Calibrate the
humidity generator upon initial installation, within 370 days before
verifying the H2O measurement of the analyzer, and after major
maintenance. Use the uncertainties from the calibration of the humidity
generator's measurements and follow NIST Technical Note 1297
(incorporated by reference, see Sec. 1065.1010) to verify that the
amount of H2O in the calibration gas, xH2Oref, is
determined within 3% uncertainty, UxH2O. If the
humidity generator requires assembly before use, after assembly follow
the instrument manufacturer's instructions to check for leaks. You may
generate the H2O calibration gas using one of the following
options:
* * * * *
0
157. Amend Sec. 1065.920 by revising paragraph (b)(6)(ii) to read as
follows:
Sec. 1065.920 PEMS calibrations and verifications.
* * * * *
(b) * * *
(6) * * *
(ii) The entire set of test-interval results passes the 95%
confidence alternative-procedure statistics for field testing (t-test
and F-test) specified in Sec. 1065.12.
0
116. Amend Sec. 1065.935 by revising paragraphs (c), (d)(2), and
(g)(4)(ii) and (5) to read as follows:
Sec. 1065.935 Emission test sequence for field testing.
* * * * *
(c) Start testing as follows:
(1) If the engine is already running and warmed up and starting is
not part of field testing, start the field test by simultaneously
starting to sample exhaust, record engine and ambient data, and
integrate measured values using a PEMS.
(2) If engine starting is part of field testing, start field
testing by simultaneously starting to sample from the exhaust system,
record engine and ambient data, and integrate measured values using a
PEMS. Then start the engine.
(d) * * *
(2) Between each test interval, reset batch storage media as
needed.
* * * * *
(g) * * *
(4) * * *
(ii) Invalidate any data that does not meet the drift criterion in
Sec. 1065.550. For HC, invalidate any data if the difference between
the uncorrected and the corrected brake-specific HC emission values are
not within 10% of the uncorrected results or the applicable
standard, whichever is greater.
(5) Verify PEMS gas analyzers used to determine bin emission values
as follows:
(i) For analyzer outputs exceeding 100% of the selected gas
analyzer range, calculate emission results using the reported value.
Invalidate data if more than 1% of recorded 1 Hz data used to determine
bin emission values exceeds 100% of the selected gas analyzer range.
For NOX or CO2, invalidate data from the entire
shift-day for all pollutants, and retest the engine. For other
pollutants, invalidate data from the entire shift-day, but only for the
affected gas analyzer. Retest the engine if the standard-setting part
requires it.
(ii) Verify drift for CO and HC as described in Sec.
1065.550(b)(3)(i)(A) and verify drift for CO2 as described
in Sec. 1065.550(b)(3)(ii)(A). Verify drift for CO, CO2,
and HC bin testing based on the interval between analyzer
verifications. For CO and CO2, invalidate data for periods
in which the respective analyzer does not meet the drift criterion in
Sec. 1065.550. For HC, invalidate data if the difference between the
uncorrected and the corrected HC emission values are not within 10% of the uncorrected results or the applicable standard,
whichever is greater.
(iii) For PEMS NOX analyzers used to determine bin
emission values, do not apply the drift verification criteria specified
in Sec. 1065.550. Invalidate data for all pollutants over the entire
shift-day if the NOX analyzer does not meet the following
drift limits:
(A) The allowable analyzer zero-drift between successive zero
verifications is
[[Page 43270]]
2.5 ppm. The analyzer zero-drift limit over the shift-day
is 10 ppm.
(B) The allowable analyzer span-drift limit between successive span
verifications is 4% of the measured span gas value
preceding the interval.
* * * * *
0
117. Amend Sec. 1065.940 by revising paragraph (a) to read as follows:
Sec. 1065.940 Emission calculations.
(a) Perform emission calculations as described in Sec. 1065.650 to
calculate emissions for each test interval using any applicable
information and instructions in the standard-setting part.
* * * * *
0
118. Amend Sec. 1065.1001 by:
0
a. Removing the definition of ``Alternate procedures'';
0
b. Adding the definitions of ``Alternative procedures'' and ``Gas
analyzer range'' in alphabetical order; and
0
c. Revising the definitions of ``Oxygenated fuels'' and ``Span''.
The additions and revisions read as follows:
Sec. 1065.1001 Definitions.
* * * * *
Alternative procedures means procedures allowed under Sec.
1065.10(c)(7).
* * * * *
Gas analyzer range means the lesser of the following values:
(1) 103% of the highest point on the linearity verification.
(2) Span gas value divided by 0.75.
* * * * *
Oxygenated fuels means fuels composed of at least 25% oxygen-
containing compounds by volume, such as ethanol or methanol. Testing
engines that use oxygenated fuels generally requires the use of the
sampling methods in subpart I of this part. However, you should read
the standard-setting part and subpart I of this part to determine
appropriate sampling methods.
* * * * *
Span means to adjust an instrument so that it gives a proper
response to a calibration standard that represents between 75% and 100%
of the range of the instrument or expected range of use.
* * * * *
0
119. Amend Sec. 1065.1005 by revising the entry for ``test,alt'' in
Table 5 in paragraph (e) to read as follows:
Sec. 1065.1005 Symbols, abbreviations, acronyms, and units of
measure.
* * * * *
(e) * * *
Table 5 of Sec. 1065.1005--Subscripts
------------------------------------------------------------------------
Subscript Meaning
------------------------------------------------------------------------
* * * * * * *
test,alt............................... alternative test quantity.
* * * * * * *
------------------------------------------------------------------------
* * * * *
0
120. Amend Sec. 1065.1010 by revising paragraphs (a) and (b) to read
as follows:
Sec. 1065.1010 Incorporation by reference.
Certain material is incorporated by reference into this part with
the approval of the Director of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, EPA must publish a document in the Federal
Register and the material must be available to the public. All approved
incorporation by reference (IBR) material is available for inspection
at EPA and at the National Archives and Records Administration (NARA).
Contact EPA at: U.S. EPA, Air and Radiation Docket Center, WJC West
Building, Room 3334, 1301 Constitution Ave. NW, Washington, DC 20004;
www.epa.gov/dockets; (202) 202-1744. For information on inspecting this
material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from the following sources:
(a) ASTM International (ASTM). ASTM International, 100 Barr Harbor
Dr., P.O. Box C700, West Conshohocken, PA 19428-2959; (610) 832-9585;
www.astm.org.
(1) ASTM D86-23ae2, Standard Test Method for Distillation of
Petroleum Products and Liquid Fuels at Atmospheric Pressure, approved
December 1, 2023 (ASTM D86); IBR approved for Sec. Sec. 1065.703(b);
1065.710(b) and (c).
(2) ASTM D93-26, Standard Test Methods for Flash Point by Pensky-
Martens Closed Cup Tester, approved March 1, 2026 (ASTM D93); IBR
approved for Sec. 1065.703(b).
(3) ASTM D130-26, Standard Test Method for Corrosiveness to Copper
from Petroleum Products by Copper Strip Test, approved March 1, 2026
(ASTM D130); IBR approved for Sec. 1065.710(b).
(4) ASTM D381-25, Standard Test Method for Gum Content in Fuels by
Jet Evaporation, approved April 1, 2025 (ASTM D381); IBR approved for
Sec. 1065.710(b).
(5) ASTM D445-24, Standard Test Method for Kinematic Viscosity of
Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity);
approved April 1, 2024 (ASTM D445); IBR approved for Sec. 1065.703(b).
(6) ASTM D525-12a (Reapproved 2025), Standard Test Method for
Oxidation Stability of Gasoline (Induction Period Method); approved
December 1, 2025 (ASTM D525); IBR approved for Sec. 1065.710(b).
(7) ASTM D613-25a, Standard Test Method for Cetane Number of Diesel
Fuel Oil, approved November 1, 2025 (ASTM D613); IBR approved for Sec.
1065.703(b).
(8) ASTM D1267-23, Standard Test Method for Gage Vapor Pressure of
Liquefied Petroleum (LP) Gases (LP-Gas Method), approved March 1, 2023
(ASTM D1267); IBR approved for Sec. 1065.720(a).
(9) ASTM D1319-20a, Standard Test Method for Hydrocarbon Types in
Liquid Petroleum Products by Fluorescent Indicator Adsorption, approved
August 1, 2020 (ASTM D1319); IBR approved for Sec. 1065.710(c).
(10) ASTM D1838-21, Standard Test Method for Copper Strip Corrosion
by Liquefied Petroleum (LP) Gases, approved July 1, 2021 (ASTM D1838);
IBR approved for Sec. 1065.720(a).
(11) ASTM D1945-25, Standard Test Method for Analysis of Natural
Gas by Gas Chromatography, approved August 1, 2025 (ASTM D1945); IBR
approved for Sec. 1065.715(a).
(12) ASTM D2158-21, Standard Test Method for Residues in Liquefied
[[Page 43271]]
Petroleum (LP) Gases, approved July 1, 2021 (ASTM D2158); IBR approved
for Sec. 1065.720(a).
(13) ASTM D2163-23e1, Standard Test Method for Determination of
Hydrocarbons in Liquefied Petroleum (LP) Gases and Propane/Propene
Mixtures by Gas Chromatography, approved March 1, 2023 (ASTM D2163);
IBR approved for Sec. 1065.720(a).
(14) ASTM D2598-21, Standard Practice for Calculation of Certain
Physical Properties of Liquefied Petroleum (LP) Gases from
Compositional Analysis, approved April 1, 2021 (ASTM D2598); IBR
approved for Sec. 1065.720(a).
(15) ASTM D2622-24, Standard Test Method for Sulfur in Petroleum
Products by Wavelength Dispersive X-ray Fluorescence Spectrometry,
approved July 1, 2024 (ASTM D2622); IBR approved for Sec. Sec.
1065.703(b); 1065.710(b) and (c).
(16) ASTM D2699-25, Standard Test Method for Research Octane Number
of Spark-Ignition Engine Fuel, approved November 1, 2025 (ASTM D2699);
IBR approved for Sec. 1065.710(b).
(17) ASTM D2700-26, Standard Test Method for Motor Octane Number of
Spark-Ignition Engine Fuel, approved May 1, 2026 (ASTM D2700); IBR
approved for Sec. 1065.710(b).
(18) ASTM D2713-24, Standard Test Method for Dryness of Propane
(Valve Freeze Method), approved October 1, 2024 (ASTM D2713); IBR
approved for Sec. 1065.720(a).
(19) ASTM D2986-95a (Reapproved 1999), Standard Practice for
Evaluation of Air Assay Media by the Monodisperse DOP (Dioctyl
Phthalate) Smoke Test, approved September 10, 1995 (ASTM D2986); IBR
approved for Sec. 1065.170(c). (Note: This standard was withdrawn by
ASTM.)
(20) ASTM D3231-25, Standard Test Method for Phosphorus in
Gasoline, approved March 1, 2024 (ASTM D3231); IBR approved for Sec.
1065.710(b) and (c).
(21) ASTM D3237-22, Standard Test Method for Lead in Gasoline By
Atomic Absorption Spectroscopy, approved May 1, 2025 (ASTM D3237); IBR
approved for Sec. 1065.710(b) and (c).
(22) ASTM D4052-22, Standard Test Method for Density, Relative
Density, and API Gravity of Liquids by Digital Density Meter, approved
May 1, 2022 (ASTM D4052); IBR approved for Sec. 1065.703(b).
(23) ASTM D4629-24, Standard Test Method for Trace Nitrogen in
Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and
Chemiluminescence Detection, approved October 1, 2024 (ASTM D4629); IBR
approved for Sec. 1065.655(e).
(24) ASTM D4815-22, Standard Test Method for Determination of MTBE,
ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1 to C4 Alcohols in
Gasoline by Gas Chromatography, approved April 1, 2022 (ASTM D4815);
IBR approved for Sec. 1065.710(b).
(25) ASTM D5186-24, Standard Test Method for Determination of the
Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels By
Supercritical Fluid Chromatography, approved July 1, 2024 (ASTM D5186);
IBR approved for Sec. 1065.703(b).
(26) ASTM D5191-22, Standard Test Method for Vapor Pressure of
Petroleum Products and Liquid Fuels (Mini Method), approved July 1,
2022 (ASTM D5191); IBR approved for Sec. 1065.710(b) and (c).
(27) ASTM D5291-26, Standard Test Methods for Instrumental
Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products
and Lubricants, approved March 1, 2026 (ASTM D5291); IBR approved for
Sec. 1065.655(e).
(28) ASTM D5453-25, Standard Test Method for Determination of Total
Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel, Diesel Engine
Fuel, and Engine Oil by Ultraviolet Fluorescence, approved July 1, 2025
(ASTM D5453); IBR approved for Sec. Sec. 1065.703(b); 1065.710(b).
(29) ASTM D5599-22, Standard Test Method for Determination of
Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame
Ionization Detection, approved April 1, 2022 (ASTM D5599); IBR approved
for Sec. Sec. 1065.655(e); 1065.710(b).
(30) ASTM D5762-24 Standard Test Method for Nitrogen in Petroleum
and Petroleum Products by Boat-Inlet Chemiluminescence, approved July
1, 2024 (ASTM D5762); IBR approved for Sec. 1065.655(e).
(31) ASTM D5769-25, Standard Test Method for Determination of
Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas
Chromatography/Mass Spectrometry, approved October 1, 2025 (ASTM
D5769); IBR approved for Sec. 1065.710(b).
(32) ASTM D6348-12 (Reapproved 2020), Standard Test Method for
Determination of Gaseous Compounds by Extractive Direct Interface
Fourier Transform Infrared (FTIR) Spectroscopy, approved December 1,
2020 (ASTM D6348); IBR approved for Sec. Sec. 1065.257(b);
1065.266(c); 1065.275(b); 1065.277(b).
(33) ASTM D6550-25, Standard Test Method for Determination of
Olefin Content of Gasolines by Supercritical-Fluid Chromatography,
approved October 1, 2025 (ASTM D6550); IBR approved for Sec.
1065.710(b).
(34) ASTM D6667-21, Standard Test Method for Determination of Total
Volatile Sulfur in Gaseous Hydrocarbons and Liquefied Petroleum Gases
by Ultraviolet Fluorescence, approved April 1, 2021 (ASTM D6667); IBR
approved for Sec. 1065.720(a).
(35) ASTM D7039-24, Standard Test Method for Sulfur in Gasoline,
Diesel Fuel, Jet Fuel, Kerosine, Biodiesel, Biodiesel Blends, and
Gasoline-Ethanol Blends by Monochromatic Wavelength Dispersive X-ray
Fluorescence Spectrometry, approved December 1, 2024 (ASTM D7039); IBR
approved for Sec. Sec. 1065.703(b); 1065.710(b).
(36) ASTM E178-21, Standard Practice for Dealing With Outlying
Observations, approved June 1, 2021 (ASTM E178); IBR approved for Sec.
1065.1121(d).
(37) ASTM F1471-09, Standard Test Method for Air Cleaning
Performance of a High-Efficiency Particulate Air Filter System,
approved March 1, 2009 (ASTM F1471); IBR approved for Sec. 1065.1001.
(Note: This standard was withdrawn by ASTM.)
(b) California Air Resources Board. California Air Resources Board,
Southern California Headquarters--Mary D. Nichols Campus, 4001 Iowa
Avenue, Riverside, CA 92507; (800) 242-4450; www.arb.ca.gov.
(1) California Non-Methane Organic Gas Test Procedures, Amended
July 30, 2002, Mobile Source Division, California Air Resources Board;
IBR approved for Sec. 1065.805(f).
(2) [Reserved]
* * * * *
0
121. Add Sec. 1065.1102 to subpart L before the center header ``Semi-
Volatile Organic Compounds'' to read as follows:
Sec. 1065.1102 Calibrations and verifications.
(a) Subsystem calibrations and verifications. Use all the
applicable calibrations and verifications in subpart D of this part,
including the linearity verifications in Sec. 1065.307, to calibrate
and verify each measurement system listed in Table 1 of this section,
for the procedures in this subpart L. This section does not apply to
systems used to gather data to inform accelerated aftertreatment aging
processes.
(b) Performance criteria for measurement systems. Table 1 follows:
[[Page 43272]]
Table 1 of Sec. 1065.1102--Subpart L Measurement Systems That Require Linearity Verification
----------------------------------------------------------------------------------------------------------------
Measurement system Applicable section Recommended method Use Linearity criteria
----------------------------------------------------------------------------------------------------------------
Vanadium Sublimation
----------------------------------------------------------------------------------------------------------------
Catalyst inlet gas temperature.. Sec. Thermocouple...... Catalyst aging (\a\)
1065.1117(b). temperature.
Catalyst bed temperature........ Sec. Thermocouple...... Catalyst aging (\a\)
1065.1117(b). temperature.
Individual gas flow rates....... Sec. Mass flow meter... Control of inlet (\a\)
1065.1117(a)(1). gas mixture.
Total flow rate................. Sec. Mass flow meter... Verification of 5% of
1065.1117(a)(2). catalyst space target.
velocity.
Gas analyzer performance........ Sec. Gas analytical Verification of (\a\)
1065.1117(a)(2). system. inlet conditions.
Sample weights.................. Sec. Balance........... ICP sample mass (\a\)
1065.1121(a)(1). determination.
----------------------------------------------------------------------------------------------------------------
Thermal Reactivity Coefficient Gas Stand
----------------------------------------------------------------------------------------------------------------
Catalyst inlet gas temperature.. Sec. Thermocouple...... Catalyst aging (\a\)
1065.1137(c)(2). temperature.
Catalyst bed temperature........ Sec. Thermocouple...... Catalyst aging (\a\)
1065.1137(c)(2). temperature.
Individual gas flow rates....... Sec. Mass flow meter... Control of inlet (\a\)
1065.1137(c)(2). gas mixture.
Total flow rate................. Sec. Mass flow meter... Verification of 5% of
1065.1137(c)(2). catalyst space target.
velocity.
Gas analyzer performance........ Sec. Gas analytical Verification of (\a\)
1065.1137(c)(2). system. inlet conditions.
----------------------------------------------------------------------------------------------------------------
Engine-Based Aging Stand
----------------------------------------------------------------------------------------------------------------
Exhaust flow rate to Sec. 1065.1141.. Air flow + fuel Initial Cycle (\a\)
aftertreatment. Sec. flow. Development.
1065.1145(a)(1)(i
).
Sec. 1065.1141.. Direct measurement Initial Cycle (\a\)
Sec. Development.
1065.1145(a)(1).
Bulk Oil Consumption............ Sec. Good engineering Initial Cycle (\a\)
1065.1141(f). judgement. Development and
Sec. Cycle Validation.
1065.1145(a)(1)(i
).
Sec.
1065.1145(e)(2).
Volatile Oil Consumption........ Sec. Mass flow meter... Initial Cycle (\a\)
1065.1141(i). Development and.
Sec. Cycle Validation..
1065.1145(a)(1)(i
).
Sec.
1065.1145(e)(2).
Secondary Oil Exposure.......... Sec. DPF weights....... Cycle Validation.. (\a\)
1065.1141(h).
Sec.
1065.1145(e)(2)(i
i).
Sulfur Exposure (choose one Sec. Mass flow meter... Cycle Validation.. (\a\)
method). 1065.1141(j).
Sec.
1065.1145(e)(2)(i
ii).
Sec. Mass flow meter... Cycle Validation.. (\a\)
1065.1141(k).
Sec.
1065.1145(e)(2)(i
ii).
----------------------------------------------------------------------------------------------------------------
Burner-Based Aging Stand
----------------------------------------------------------------------------------------------------------------
Exhaust flow rate to Sec. 1065.1143.. Direct measurement Initial Cycle (\a\)
aftertreatment. Sec. Development.
1065.1145(a)(2)(i
).
Bulk Oil Consumption............ Sec. DPF weights....... Initial Cycle (\a\)
1065.1143(d). Development and
Sec. Cycle Validation.
1065.1145(a)(2)(i
).
Sec.
1065.1145(e)(2).
Volatile Oil Consumption........ Sec. DPF weights....... Initial Cycle (\a\)
1065.1143(e). Development and
Sec. Cycle Validation.
1065.1145(a)(2)(i
).
Sec.
1065.1145(e)(2).
Secondary Oil Exposure.......... Sec. DPF weights....... Cycle Validation.. (\a\)
1065.1143(d).
Sec.
1065.1145(e)(2)(i
i).
Sulfur Exposure (choose one Sec. Mass flow meter... Cycle Validation.. (\a\)
method). 1065.1143(i).
Sec.
1065.1145(e)(2)(i
ii).
Sec. Mass flow meter... Cycle Validation.. (\a\)
1065.1143(j).
Sec.
1065.1145(e)(2)(i
ii).
----------------------------------------------------------------------------------------------------------------
Aging Bench
----------------------------------------------------------------------------------------------------------------
Catalyst inlet gas temperature.. Sec. Thermocouple...... Catalyst aging (\a\)
1065.1153(a). temperature.
Catalyst bed temperature........ Sec. Thermocouple...... Catalyst aging (\a\)
1065.1153(c). temperature.
Sec.
1065.1155(f).
Individual gas flow rates....... Sec. Mass flow meter... Control of inlet (\a\)
1065.1153(a). gas mixture.
Sec.
1065.1153(b).
[[Page 43273]]
Total flow rate................. Sec. Mass flow meter... Verification of 5% of
1065.1153(b). catalyst space target.
Sec. velocity.
1065.1155(h).
----------------------------------------------------------------------------------------------------------------
\a\ See Table 1 of Sec. 1065.307 for linearity criteria.
0
122. Revise and republish Sec. 1065.1115 to read as follows:
Sec. 1065.1115 Reactor design and setup.
Vanadium measurements rely on a reactor that adsorbs sublimation
vapors of vanadium onto an alumina capture bed with high surface area.
(a) Configure the reactor with the alumina capture bed downstream
of the catalyst in the reactor's hot zone to adsorb vanadium vapors at
high temperature. You may use quartz beads upstream of the catalyst to
help stabilize reactor gas temperatures. Select an alumina material and
design the reactor to minimize sintering of the alumina. For a 1-inch
diameter reactor, use 4 to 5 g of \1/8\ inch extrudates or -14/+24 mesh
(approximately 0.7 to 1.4 mm) gamma alumina (such as Alfa Aesar,
aluminum oxide, gamma, catalyst support, high surface area, bimodal).
Position the alumina downstream from either an equivalent amount of -
14/+24 mesh catalyst sample or an approximately 1-inch diameter by 1-
inch to 3-inch-long catalyst-coated monolith sample cored from the
production-intent vanadium catalyst substrate. Separate the alumina
from the catalyst with a 0.2 to 0.4 g plug of quartz wool. Place a
short 4 g plug of quartz wool downstream of the alumina to maintain the
position of that bed. Use good engineering judgment to adjust as
appropriate for reactors of different sizes.
(b) Include the quartz wool with the capture bed to measure
vanadium content. We recommend analyzing the downstream quartz wool
separately from the alumina to see if the alumina fails to capture some
residual vanadium.
(c) Configure the reactor such that both the sample and capture
beds are in the reactor's hot zone. Design the reactor to maintain
similar temperatures in the capture bed and catalyst. Monitor the
catalyst and alumina temperatures with Type K thermocouples inserted
into a thermocouple well that is in contact with the catalyst sample
bed.
(d) You may include an ammonia slip catalyst as part of the
catalyst-coated monolith sample if it is part of the production
aftertreatment system. Size the ammonia slip catalyst based on its
volume ratio to the vanadium catalyst and locate it in the reactor
heated zone. Ensure that the ratio of the vanadium catalyst core volume
to ammonia slip catalyst core volume is consistent with the highest
production system volume ratio of vanadium to ammonia slip catalyst you
expect. You may use a small amount of quartz wool between the vanadium
and ammonia slip catalysts to address catalyst core alignment. You may
exceed the 3-inch maximum core length in paragraph (a) of this section
by up to 3 inches.
(e) If there is a risk that the quartz wool and capture bed are not
able to collect all the vanadium, configure the reactor with an
additional capture bed and quartz wool plug just outside the hot zone
and analyze the additional capture bed and quartz wool separately.
(f) An example of a catalyst-coated monolith and capture bed
arrangement in the reactor tube are shown in the following figure:
[GRAPHIC] [TIFF OMITTED] TP14JY26.080
(g) You may need to account for vanadium-loaded particles
contaminating catalyst-coated monoliths as a result of physical
abrasion. To do this correction, your sample must show levels of
vanadium, titanium, and either
[[Page 43274]]
tungsten, antimony, or other metals contained in the catalyst-coated
monolith above their respective method detection limits. Using these
values and available information about the ratio of vanadium to
titanium in the catalyst, subtract the mass of vanadium catalyst
material associated with the catalyst particles from the total measured
vanadium on the capture bed to determine the vanadium recovered due to
sublimation as described in Sec. 1065.1121(e).
0
123. Revise and republish Sec. 1065.1117 to read as follows:
Sec. 1065.1117 Reactor aging cycle for determination of vanadium
sublimation temperature.
This section describes the conditions and process required to
operate the reactor described in Sec. 1065.1115 for collection of the
vanadium sublimation samples for determination of vanadium sublimation
temperature. The reactor aging cycle constitutes the process of testing
the catalyst sample over all the test conditions described in paragraph
(b) of this section.
(a) Set up the reactor to flow gases with a space velocity of at
least 35,000/hr over the catalyst-coated monolith system with a
pressure drop across the catalyst and capture bed less than 35 kPa.
(1) Calculate space velocity as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.081
Where:
Vstdreactor = the mean volume flow rate through the
reactor at conditions of 293.15 K and 101.325 kPa.
Vmonolith = the total volume of the catalyst-coated
monolith system. When determining space velocity for a reactor blank
test, use the volume for a 1-inch diameter by 1-inch-long monolith.
Example:
Vstdreactor = 0.4502 m3/hr
Vmonolith = 0.0000128638 m3
[GRAPHIC] [TIFF OMITTED] TP14JY26.082
SV = 34,997/hr
(2) Use test gases meeting the following specifications, noting
that not all gases will be used at the same time:
(i) 5 vol% O2, balance N2.
(ii) NO, balance N2. Use an NO concentration of (200 to
500) ppm.
(iii) NH3, balance N2. Use an NH3
concentration of (200 to 500) ppm.
(b) Perform testing as follows:
(1) Add a new catalyst sample and capture bed into the reactor as
described in Sec. 1065.1113. Heat the reactor to 550 [deg]C while
flowing the oxygen blend specified in paragraph (a)(2) of this section
as a pretest gas mixture. Ensure that no H2O is added to the
pretest gas mixture to reduce the risk of sintering and vanadium
sublimation.
(2) Start testing at a temperature that is lower than the point at
which vanadium starts to sublime. Start testing when the reactor
reaches 550 [deg]C unless testing supports a lower starting
temperature. Once the reactor reaches the starting temperature and the
catalyst has been equilibrated to the reactor temperature, flow NO and
NH3 test gases for 18 hours with a nominal H2O
content of 10 volume percent. This volume percentage of H2O
is appropriate and must be used for diesel fueled compression-ignition
engines. If you perform this testing for engines that use a different
fuel than diesel, use good engineering judgment to select an
H2O volume percentage consistent with the maximum expected
exhaust H2O content for that fuel. For example, you might
test at an H2O content of 20 volume percent for a lean-burn,
spark-ignition hydrogen-fueled engine. If an initial starting
temperature of 550 [deg]C results in vanadium sublimation, you may
retest using a new catalyst sample and a lower initial starting
temperature.
(3) After 18 hours of exposure, flow the pretest oxygen blend as
specified in paragraph (b)(1) of this section and allow the reactor to
cool down to room temperature.
(4) Analyze the sample as described in Sec. 1065.1121.
(5) Repeat the testing in paragraphs (b)(1) through (4) of this
section by raising the reactor temperature in increments of up to 25
[deg]C, until you reach the temperature at which vanadium sublimation
begins above the method detection limit threshold determined in Sec.
1065.1121.
(7) You may optionally test in a manner other than testing a single
catalyst formulation in series across all test temperatures. For
example, you may test additional samples at the same reactor
temperature before moving on to the next temperature.
(c) Determine the effective sublimation temperature as follows:
(1) Select the data from the lowest temperature where you detected
a vanadium level above the method detection limit threshold and the
next lowest temperature where vanadium sublimation was not detected
above the threshold.
(2) Use linear interpolation between the two data points to
determine the temperature at which the vanadium level crosses the
method detection limit threshold.
(3) Calculate the sublimation temperature, Tsublimation,
as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.083
Where:
MDLthreshold = the vanadium method detection limit
threshold in Sec. 1065.1121(d)(3). This value of 10 [micro]g/
m3 is based on the total volume that flowed through the
catalyst core at a space velocity of 35,000/hr for 18 hours, for a
standard 1-inch diameter by 1-inch-long catalyst core. If you test a
different size catalyst core, you must scale the method detection
limit threshold value as described in Sec. 1065.1121(d)(4).
VL = the vanadium result from the highest test point
where vanadium sublimation was below the method detection limit
threshold.
VH = the vanadium result from the lowest test point where
vanadium sublimation was at or above the method detection limit
threshold.
TH = the temperature at which VH was determined.
TL = the temperature at which VL was determined.
Example:
MDLthreshold = 10 [micro]g/m3
VL = 5.1 [micro]g/m3
VH = 12.5 [micro]g/m3
TH = 585 [deg]C
TL = 560 [deg]C
[[Page 43275]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.084
Tsublimation = 577 [deg]C
0
124. Revise and republish Sec. 1065.1119 to read as follows:
Sec. 1065.1119 Blank testing.
This section describes the process for analyzing blanks. Use blanks
to determine the background effects and the potential for contamination
from the sampling process.
(a) Take blanks from the same batch of alumina used for the capture
bed.
(b) Media blanks are used to determine if there is any
contamination in the sample media. Analyze at least one media blank for
each reactor aging cycle or round of testing performed under Sec.
1065.1117. If your sample media is taken from the same lot, you may
analyze media blanks less frequently consistent with good engineering
judgment.
(c) Reactor blanks are used to determine the method detection limit
and can be used to determine if there is any contamination from the
sampling system. Analyze at least one reactor blank for each reactor
aging cycle or round of testing performed under Sec. 1065.1117.
(1) Test reactor blanks with the reactor on and operated
identically to that of a catalyst test in Sec. 1065.1117 with the
exception that when loading the reactor, only the alumina capture bed
will be loaded (no catalyst sample is loaded for the reactor blank). We
recommend acquiring reactor blanks with the reactor operating at a 750
[deg]C test temperature. If your reactor cannot maintain 750 [deg]C,
acquire the reactor blanks at the highest temperature your reactor can
maintain.
(2) You must run at least three reactor blanks if the result from
the initial blank analysis is above the detection limit of the method,
with additional blank runs based on the uncertainty of the reactor
blank measurements, consistent with good engineering judgment.
(3) If the volumetric flow during the vanadium sublimation test is
higher than what was flowed during the reactor blank test, scale the
method detection limit and method detection limit threshold to account
for the volumetric flow differences. This will typically occur in
instances where a catalyst coated monolith is tested that has a volume
that is greater than the standard 1'' diameter by 1'' long catalyst
core, as the volumetric flow rate through the catalyst core is
increased to maintain the target space velocity of 35,000/hr. Adjust
the method detection limit as described in Sec. 1065.1121(d)(4).
0
125. Revise Sec. 1065.1121 to read as follows:
Sec. 1065.1121 Vanadium sample dissolution and analysis in alumina
capture beds.
This section describes the process for dissolution of vanadium from
the vanadium sublimation samples collected in Sec. 1065.1117 and any
blanks collected in Sec. 1065.1119 as well as the analysis of the
digestates to determine the mass of vanadium (as well as titanium,
tungsten and antimony if you are testing for those elements) emitted
during the reactor aging cycle.
(a) Digest the samples using the following procedure, or an
equivalent procedure:
(1) Place the recovered alumina, a portion of the ground quartz
tube from the reactor, and the quartz wool in a Teflon pressure vessel
with a mixture made from 1.5 mL of 16 N HNO3, 0.5 mL of 28 N
HF, and 0.2 mL of 12 N HCl. Note that you must weigh all the sample
materials submitted to the digestion process (including alumina, quartz
wool, and quartz tube). Note that the amount of ground quartz tube from
the reactor included in the digestion can influence the vanadium
concentration of both the volatilized vanadium from the sample and the
method detection limit. You must be consistent with the amount ground
quartz tube included in the sample analysis for your testing. You must
limit the amount of quartz tube to include only portions of the tube
that would be likely to encounter volatilized vanadium.
(2) Program a microwave oven to heat the sample to 180 [deg]C over
9 minutes, followed by a 10-minute hold at that temperature, and 1 hour
of ventilation/cooling.
(3) After cooling, dilute the digests to 30 mL with high purity
18M[Omega] water prior to ICP-MS (or ICP-OES) analysis. Note that this
digestion technique requires adequate safety measures when working with
HF at high temperature and pressure. To avoid ``carry-over''
contamination, rigorously clean the vessels between samples as
described in ``Microwave digestion procedures for environmental
matrixes'' (Lough, G.C. et al, Analyst. 1998, 123 (7), 103R-133R).
(b) Analyze the digestates for vanadium as follows:
(1) Perform the analysis using ICP-OES (or ICP-MS) using standard
plasma conditions (1350 W forward power) and a desolvating
microconcentric nebulizer, which will significantly reduce oxide- and
chloride-based interferences.
(2) We recommend that you digest and analyze a minimum of three
solid vanadium NIST Standard Reference Materials in duplicate with
every batch of 25 vanadium alumina capture bed samples that you analyze
in this section, as described in ``Emissions of metals associated with
motor vehicle roadways'' (Herner, J.D. et al., Environmental Science
and Technology. 2005, 39, 826-836). This will serve as a quality
assurance check to help gauge the relative uncertainties in each
measurement, specifically if the measurement errors are normally
distributed and independent.
(c) Calculate your vanadium result, Vmeas, in [micro]g/
m3 using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.085
Where:
xICP = the ICP measured mass concentration of vanadium.
If the mass concentration is below the instrument detection limit,
use the instrument detection limit in place of the measured value.
msample = total sample mass determined in paragraph
(a)(1) of this section.
Vreactor = the total gas volume flowed through the
reactor during the catalyst-coated monolith test.
Example:
xICP = 0.74 mg/m3
msample = 114.839 g
Vreactor = 8.104223 m3
[GRAPHIC] [TIFF OMITTED] TP14JY26.086
Vmeas = 10.5 [micro]g/m3
(d) Use the 3-sigma approach to determine the analytical method
detection limits for vanadium. This process involves analyzing at least
seven replicates of a reactor blank using the analytical method
described in paragraphs (a) and (b)(1) of this section, converting the
responses into concentration units, and calculating the standard
deviation. Determine the detection limit by multiplying the standard
deviation by 3 and adding it to the median. Determine the following
analytical method detection limits:
(1) Determine the ICP-MS (or ICP-OES) instrumental detection limit
(mg/
[[Page 43276]]
kg) by measuring at least seven blank samples made up of the reagents
from paragraph (a) of this section.
(2) Determine the method detection limit ([micro]g/m3 of
flow) by measuring at least seven reactor blank samples taken as
described in Sec. 1065.1119(d). You may check for and remove any
outliers using Section 7 of ASTM E178 (incorporated by reference, see
Sec. 1065.1010). Maintain a rolling method detection limit, updating
it by removing the oldest reactor blank results as new reactor blank
samples are taken. Repeat the outlier analysis each time you generate a
new reactor blank and update the data set. Maintain at least seven
blanks in the data set. Use good engineering judgment to add new blanks
and remove old blanks from the data set as needed. For example, if the
lot of capture blank material changes or if your testing involves
submission of multiple groups of samples that are submitted for ICP
analysis at different times.
(3) Your method detection limit determined under paragraph (d)(2)
of this section must be at or below a threshold of 10 [micro]g/
m3. Note that this method detection limit threshold is based
on the total volume that flowed through the catalyst core at a space
velocity of 35,000/hr for 18 hours, for a standard 1-inch diameter by
1-inch-long catalyst core. If you test at a different size catalyst
core, you must scale both your calculated method detection limit and
the threshold value as described in paragraph (d)(4) of this section.
You must report your method detection limit determined in this
paragraph (d)(3) with your test results. Report your method detection
limit at a precision of two significant figures. Report your results
and calculated method detection limit at the same level of precision as
the threshold.
(4) When your catalyst core volume dictates a total volume flowed
through the catalyst core that is greater than the total volume flowed
during the reactor blank test, scale the method detection limit
threshold from paragraph (d)(3) of this section and the lab determined
method detection limit as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.087
Where:
MDL[type] = method detection limit threshold from
paragraph (d)(3) of this section or lab determined method detection
limit from paragraph (d)(2) of this section.
Vstdblank = the total gas volume flowed through the
reactor during a standard lab reactor blank test (assuming a 1-inch
diameter and 1-inch-long core).
Vreactor = the total gas volume flowed through the
reactor during the catalyst coated monolith test.
Example for a catalyst coated monolith system that contains a 1''
diameter by 1'' long vanadium SCR catalyst core and a 1'' diameter by
0.5'' long ammonia slip catalyst core that yields a vanadium test
result of 7.9 [micro]g/m3:
MDLthreshold = 10 [micro]g/m3 threshold, from
paragraph (d)(3) of this section.
MDLreactorblank = 4.5 [micro]g/m3, actual
determined method detection limit from paragraph (d)(2) of this
section.
Vstdblank = 8.4 m3
Vreactor = 12.2 m3
[GRAPHIC] [TIFF OMITTED] TP14JY26.088
[GRAPHIC] [TIFF OMITTED] TP14JY26.089
(5) In the example given in paragraph (d)(4) of this section, the
corrected reactor blank derived method detection limit is below the
adjusted method detection limit threshold of 4.8 [micro]g/
m3, indicating that the reactor blank derived method
detection limit meets the requirements of paragraph (d)(3) of this
section. The threshold corrected value becomes the new method detection
limit threshold, replacing the value from paragraph (d)(3) of this
section, which is compared to the reactor blank corrected method
detection limit. The corrected method detection limit threshold of 6.9
[micro]g/m3 indicates that the catalyst coated monolith
vanadium test result of 7.9 [micro]g/m3 is above the
adjusted method detection limit threshold and that vanadium has been
emitted by the monolith.
(e) You may account for vanadium-loaded particles contaminating the
catalyst-coated monoliths as a result of physical abrasion as allowed
in Sec. 1065.1115(g). This process requires that you determine the
analytical method detection limits for titanium and either tungsten,
antimony or other metals contained in the catalyst-coated monolith
using the same method as described in paragraph (d) of this section for
vanadium. You may perform this correction using either the ratio
provided by the catalyst supplier or the measured mass ratio of
vanadium to titanium.
(1) If you use the ratio provided by the catalyst supplier,
determine the corrected vanadium level, Vcor, using the
following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.090
Where:
Vmeas = the vanadium result determined in paragraph (c)
of this section.
Ratio = the mass ratio of V to Ti from the catalyst supplier or the
experimentally determined ratio, Ratiomeas, as determined
in paragraph (e)(2) of this section.
Timeas = the titanium result determined in paragraph (c)
of this section.
Example:
[[Page 43277]]
Vmeas = 6.8 [micro]g/m3
Ratiomeas = 0.025
Timeas = 223.5 [micro]g/m3
Vcor = 1.2 [micro]g/m3
(2) If you have multiple tests where you detect vanadium, titanium,
and either tungsten or antimony, you may substitute the ratio measured
during the experiments, Ratiomeas, in place of the catalyst
supplier ratio in Eq. 1065.1121-3. You may use this option only if the
measured ratios of vanadium to titanium for the test you are correcting
are within 20% of the average calculated ratio for all of the tests in
the data set that are being corrected. If you use the measured ratio
from the experiment, calculate that ratio using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.091
Where:
MDLV = the method detection limit for vanadium.
MDLTi = the method detection limit for vanadium.
Example:
Vmeas = 6.8 [micro]g/m3
MDLV = 3.1 [micro]g/m3
Timeas = 223.5 [micro]g/m3
MDLTi = 76.2 [micro]g/m3
[GRAPHIC] [TIFF OMITTED] TP14JY26.092
Ratio = 0.025
0
126. Amend Sec. 1065.1125 by revising paragraph (d)(2) to read as
follows:
Sec. 1065.1125 Exhaust opacity measurement system.
* * * * *
(d) * * *
(2) You may use smokemeters that rely on partial flow sampling.
Follow the instrument manufacturer's installation, calibration,
operation, and maintenance procedures and correct for any difference in
the path length of the exhaust plume relative to the diameter of the
engine's exhaust outlet.
0
127. Amend Sec. 1065.1127 by revising paragraphs (c)(4) and (5) to
read as follows:
Sec. 1065.1127 Test procedure for determining percent opacity.
* * * * *
(c) * * *
(4) Determine the dynamometer load needed to meet the cycle
requirements in paragraphs (d)(4)(ii) and (iv) of this section.
(5) You may program the dynamometer to apply motoring assist with
negative flywheel torque, but only during the first 0.5 seconds of the
acceleration events identified in paragraph (d)(4) of this section.
Negative flywheel torque may not exceed 13.6 N[middot]m.
* * * * *
0
128. Amend subpart L by revising the center header ``ACCELERATED
AFTERTREATMENT AGING'' to read as follows: ACCELERATED AFTERTREATMENT
AGING--COMPRESSION-IGNITION AFTERTREATMENT
0
129. Amend Sec. 1065.1133 by revising paragraph (a)(3) to read as
follows:
Sec. 1065.1133 Application selection, data gathering, and analysis.
* * * * *
(a) * * *
(3) Sulfur exposure. The total sulfur exposure is the sum of fuel-
and oil-related sulfur. Oil-related sulfur will be accounted for in the
acceleration of oil exposure directly. We recommend that you determine
fuel-related sulfur exposure by selecting an application that
represents the 90th percentile of fuel consumption. Use good
engineering judgment to determine that average rate of fuel consumption
for the target application. You may use a combination of field and
laboratory measurements to make this determination. Calculate the
average rate of fuel-related sulfur exposure in grams per hour from the
average rate of fuel consumption assuming a fuel sulfur level of 10 ppm
by weight. You may adjust the 10-ppm fuel sulfur level if the fuel your
engine operates on is shown to have a sulfur level that differs from
diesel fuel.
* * * * *
0
130. Amend Sec. 1065.1137 by revising paragraphs (d)(1)(ii)(B)(1),
(d)(2), and (d)(4)(iii)(A) to read as follows:
Sec. 1065.1137 Determination of thermal reactivity coefficient.
* * * * *
(d) * * *
(1) * * *
(ii) * * *
(B) * * *
(1) Generate a fit of the deactivation data in paragraph (d)(1)(i)
of this section at each aging temperature using the following linear
expression:
[GRAPHIC] [TIFF OMITTED] TP14JY26.093
Where:
V = N2/N1 or N2 (V is to be
normalized to the degreened V value for each new catalyst component
prior to aging, i.e., V = 1 at t = 0 for each aging temperature).
kD = the thermal aging rate constant from paragraph
(d)(1)(ii)(A) of this section.
* * * * *
(2) Iron-based zeolite or vanadium SCR. Process all NH3
TPD data from each aging condition using a GPLE to fit the
NH3 desorption data (or BTE surface area data for vanadium
SCR). Note that this expression is different from the one used in
paragraph (d)(1)(ii)(A) of this section because the model order m is
allowed to vary. This general expression takes the following form:
[GRAPHIC] [TIFF OMITTED] TP14JY26.094
Where:
V = total NH3 (or BET surface area) normalized to the
degreened value for each new catalyst component prior to aging
(i.e., V = 1 at t = 0 for each aging temperature).
kD = the thermal aging rate constant from paragraph
(d)(1)(ii)(A) of this section.
t = time.
Veq = aging metric at equilibrium (set to 0 unless there
is a known activity minimum).
m = model order.
* * * * *
(4) * * *
(iii) * * *
(A) Use the GPLE to fit the NO to NO2 conversion data,
X, at each aging temperature. The GPLE takes the following form:
[GRAPHIC] [TIFF OMITTED] TP14JY26.095
Where:
V = aging metric for diesel oxidation catalysts.
kD = the thermal aging rate constant from paragraph
(d)(4)(i) of this section.
t = aging time.
Veq = aging metric at equilibrium (set to 0 unless there
is a known activity minimum).
m = model order.
* * * * *
0
131. Amend Sec. 1065.1139 by revising paragraphs (a), (b)(1)(iii) and
(iv), (b)(2)(i), (b)(2)(v)(C), (d)(1), (e)(3), (g)(1) introductory
text, (g)(1)(iv), (g)(2)(ii), and (h) to read as follows:
Sec. 1065.1139 Aging cycle generation.
* * * * *
(a) Cycle generation process overview. The process of cycle
generation begins by determining the number of bench aging hours. The
input into this
[[Page 43278]]
calculation is the useful life in engine operating hours for the target
application. If the standard-setting part does not establish useful
life based on engine operating hours, use good engineering judgment to
determine the appropriate number of hours corresponding to the
regulatory useful life based on field data, including average vehicle
speed. Subtract service accumulation hours on an engine dynamometer
before the start of accelerated aging from the value representing the
useful life in hours. Also subtract the engine operating hours needed
to stabilize the engine before accelerated aging, and subtract 100
hours to account for stabilization after accelerated aging. The total
number of accelerated aging hours is generally equal to the useful life
in hours divided by 10 to account for the 10-fold acceleration of the
aging process; however, a different acceleration factor may apply as
specified in paragraph (e)(6)(v) of this section. As an example of the
10-fold acceleration based on the sample calculation in 40 CFR
1036.245(c)(6), if the total service accumulation representing hours of
engine operation over the useful life is 18,567 hours, engine
stabilization involved 250 hours of engine operation before initial
emission testing, and service accumulation on the dynamometer included
1,525 hours of engine operation, the target for bench-aging hours would
be 1,669 hours ((18,567-250-1,525-100)/10). Arrange the different
operating modes for repetitive temperature cycling and divide the 1669
hours over those operating modes, as outlined in paragraph (g) of this
section. In the case of periodic regeneration, split the bench-aging
hours between regeneration and normal (non-regeneration) operation. The
analysis of normal operation data is given in paragraph (b) of this
section. The analysis of regeneration data is given in paragraph (d) of
this section.
(b) * * *
(1) * * *
(iii) Check each solution, starting with the one with the highest
CCC to determine if it satisfies the following requirements:
(A) No more than one cluster contains fewer than 3% of the data
points.
(B) If that solution does not satisfy these requirements move to
the solution with the next highest CCC.
(iv) The process described in paragraph (c)(1)(iii) of this section
generally works well for most data sets, but if you have difficulty
with the CCC metric in a particular data set, use good engineering
judgment to leverage additional criteria to help the down-selection
process. Examples of alternative clustering metrics include a Davies-
Bouldin Index (optimizing on the minimum value) or a Calinski-Harabasz
Index (optimize on the maximum value).
* * * * *
(2) * * *
(i) Perform k-means clustering as described in paragraph (b)(1) of
this section but using data sets containing the two parameters recorded
in the field data sets. For example, you might use speed and torque, as
recorded both in the field and the laboratory for Method 2 clustering.
* * * * *
(v) * * *
(C) Calculate subsequent wi values after calculating
w1 as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.096
(D) Calculate the sum of the weighting factors to verify that they
are equal to one.
[GRAPHIC] [TIFF OMITTED] TP14JY26.097
Where:
n = number of regulatory cycles for the application.
* * * * *
(d) * * *
(1) The total number of regenerations that will be run during the
accelerated aging process will be the same as the total number of
regenerations over useful life. Calculate this number by dividing the
total number of useful life hours by the interval between regenerations
as determined in Sec. 1065.1133(b)(3) and subtract the number of
regenerations that occurred during service accumulation on an engine
dynamometer.
* * * * *
(e) * * *
(3) Calculate the cumulative deactivation, Dt, for the
input field data set. The time step for the calculations should be 1
second for 1-Hz input data.
(i) First calculate Dt for the non-regeneration portion
of the field data set. For Method 2 use the 1-Hz data from the
regulatory cycles as the field data set.
(ii) Divide the calculate field Dt by the number of
hours represented in the field data set.
(iii) Multiply the hourly Dt by the number of hours
required to reach useful life. This is the target
Dt,field-normi.
(iv) Multiply the total number of regenerations for useful life by
the cumulative deactivation Dt for the target regeneration
profile determined in paragraph (d)(4) of this section. This is the
target Dt,field-regen.
(v) The total target cumulative deactivation for the field data,
Dt,field, is the sum of Dt,field-normi and
Dt,field-regen.
* * * * *
(g) * * *
(1) Cycle assembly with infrequent regenerations. For systems that
use infrequent regenerations, the number of cycle repeats is equal to
the number of regeneration events that happen over useful life. The
total cycle duration of the aging cycle is calculated as the total
aging duration in hours divided by the number of infrequent
regeneration events. In the case of systems with multiple types of
infrequent regenerations, use the regeneration with the lowest
frequency to calculate the cycle duration.
* * * * *
(iv) Place the mode with the lowest temperature first, then move to
the highest temperature mode, followed by the next lowest temperature
mode, and then the next highest mode, continuing in this alternating
pattern until all modes are included. You may also place the mode with
the highest temperature first, then move to the lowest temperature
mode, followed by the next highest temperature mode, and then the next
lowest temperature mode, continuing in this alternating pattern until
all modes are included.
* * * * *
(2) * * *
(ii) Place the mode with the lowest temperature first, then move to
the highest temperature mode, followed by the next lowest temperature
mode, and then the next highest mode, continuing in this alternating
pattern until all modes are included. You may also place the mode with
the highest temperature first, then move to the lowest temperature
mode, followed by the next highest temperature mode, and then the next
lowest temperature mode, continuing in this alternating pattern until
all modes are included.
* * * * *
(h) Chemical exposure targets. Determine targets for accelerated
oil and fuel sulfur exposure as follows:
(1) Oil exposure targets. The target oil exposure rate during
accelerated aging is 10 times the field average oil consumption rate
determined in Sec. 1065.1133(a)(2). You must achieve this
[[Page 43279]]
target exposure rate on a cycle average basis during aging. Use good
engineering judgment to determine the oil exposure rates for individual
operating modes that will achieve this cycle average target. For
engine-based aging stands you will likely have different oil
consumption rates for different modes depending on the speed and load
conditions you set. For burner-based aging stands, you may find that
you have to limit oil exposure rates at low exhaust flow or low
temperature modes to ensure good atomization of injected oil. On a
cycle average basis, the portion of oil exposure from the volatile
introduction pathway (i.e., oil doped in the burner or engine fuel)
must be between (10 to 30) % of the total. The remainder of oil
exposure must be introduced through bulk pathway. We recommend that you
adjust your oil exposure to account for exposure that occurred during
service accumulation on the dynamometer.
(i) We recommend that you minimize (in the case of an engine-bench
aging stand) or turn off (in the case of a burner-based aging stand)
oil exposure during infrequent regeneration modes. If you do, you must
increase the target oil exposure rates by the ratio of total aging time
to total normal (non-regeneration) aging time. Determine this ratio,
Oacc,rate, using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.098
Where:
tul = total time required for remainder of useful life in
hours.
tacc,aging = total time of accelerated aging in hours.
tregen = required total time of infrequent regeneration
events during accelerated aging in hours.
Example:
tul = 16,692 hours
tacc,aging = 1,669 hours
tregen = 300 hours
[GRAPHIC] [TIFF OMITTED] TP14JY26.099
(ii) This example is for a burner-based aging bench and assumes
that oil exposure is completely turned off during infrequent
regeneration modes. Therefore, you would need to increase the oil
consumption rates in all non-regeneration modes by 12.19 times.
(iii) If Oacc,rate exceeds 15.0, you must increase
tacc,aging until the calculated oil exposure acceleration
rate falls below 15.0. We recommend targeting an acceleration rate of
13 or less to provide a sufficient operating window during actual
aging. You may not lower the required total time of infrequent
regeneration events during accelerated aging, tregen; therefore, the
overall time acceleration will decrease from the original target of ten
times.
(2) Fuel sulfur exposure targets. The target sulfur exposure rate
for fuel-related sulfur is determined by utilizing the field mean fuel
rate data for the engine determined in Sec. 1065.1133(a)(3). Calculate
the total sulfur exposure mass using this mean fuel rate, the total
number of non-accelerated hours to reach useful life, and a fuel sulfur
level of 10 ppmw. You may adjust the 10-ppm fuel sulfur level if the
fuel your engine operates on is shown to have a sulfur level that
differs from diesel fuel. We recommend that you adjust your sulfur
exposure to account for exposure that occurred during service
accumulation on the dynamometer.
(i) For an engine-based aging stand, if you perform accelerated
sulfur exposure by additizing engine fuel to a higher sulfur level,
determine the accelerated aging target additized fuel sulfur mass
fraction, wS, as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.100
Where:
mfuel,field = field mean fuel flow rate.
mfuel,cycle = accelerated aging cycle mean fuel flow
rate.
mSfuel,ref = reference mass of sulfur per mass of fuel =
0.00001 kg/kg.
Sacc,rate = sulfur acceleration rate = 10.
Example:
mfuel,field = 54.3 kg/hr
mfuel,cycle = 34.1 kg/hr
mSfuel,ref = 0.00001 kg/kg.
Sacc,rate = 10
[GRAPHIC] [TIFF OMITTED] TP14JY26.101
wS,target = 0.000159
(ii) If you use gaseous SO2 to perform accelerated
sulfur exposure, such as on a burner-based stand, calculate the target
SO2 concentration to be introduced, xSO2,target,
as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.102
Where:
mfuel,field = field mean fuel flow rate.
mexhaust,cycle = time weighted average exhaust flow rate
during the burner aging cycle.
xSfuel,ref = reference mol fraction of sulfur in fuel =
10 [micro]mol/mol.
Sacc,rate = sulfur acceleration rate = 10.
Mexh = molar mass of exhaust = molar mass of air.
MS = molar mass of sulfur.
Example:
mfuel,field = 54.3 kg/hr
mexhaust,cycle = 1000.8 kg/hr
xSfuel,ref = 10 [micro]mol/mol
Sacc,rate = 10
Mexh = 28.96559 g/mol
MS = 32.065 g/mol
[[Page 43280]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.103
xSO2,target = 4.90 [micro]mol/mol
(iii) We recommend that you turn off gaseous sulfur injection
during infrequent regeneration modes;, if you do this, you must
increase the target SO2 concentration by the ratio of total
aging time to total normal (non-regeneration) aging time. Determine
this ratio, Sacc,rate, using the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.104
Where:
tul = total time required for remainder of useful life in
hours.
tacc,aging = total time of accelerated aging in hours.
tregen = required total time of infrequent regeneration
events during accelerated aging in hours.
Example:
tul = 16,692 hours
tacc,aging = 1,669 hours
tregen = 300 hours
[GRAPHIC] [TIFF OMITTED] TP14JY26.105
(iv) If the updated Sacc,rate exceeds 15.0, you must
increase tacc,aging until the calculated sulfur exposure
acceleration rate falls below 15.0. We recommend targeting an
acceleration rate of 13 or less to provide a sufficient operating
window during actual aging. You may not lower the required total time
of infrequent regeneration events during accelerated aging,
tregen; therefore, the overall time acceleration will
decrease from the original target of ten times.
0
132. Amend Sec. 1065.1141 by revising paragraphs (h) and (j) to read
as follows:
Sec. 1065.1141 Facility requirements for engine-based aging stands.
* * * * *
(h) If the engine-aging stand will be used for aging of systems
that incorporate a diesel particulate filter (DPF), we recommend you
perform secondary tracking of oil exposure by using clean (soot free)
DPF weights to track ash loading and compare this mass of ash to the
amount predicted using the measured oil consumption mass and the oil
ash concentration. The ratio of the mass of ash found by DPF weight
over the predicted mass of ash based on oil consumption measurements
should fall within a range of 0.55 to 0.7.
* * * * *
(j) If you perform sulfur acceleration by increasing the sulfur
level of the engine fuel, you must meet the target sulfur level within
5 ppmw. Increase the sulfur level by adding sulfur to the
entire batch of fuel or adding sulfur to the fuel line that feeds the
engine. Verify the sulfur level of the fuel prior to the start of
aging, or whenever a new batch of aging fuel is acquired.
* * * * *
0
133. Amend Sec. 1065.1143 by revising paragraph (h) and adding a new
paragraph (j) to read as follows:
Sec. 1065.1143 Requirements for burner-based aging stands.
* * * * *
(h) If the burner-based aging stand will be used for aging of
systems that incorporate a diesel particulate filter (DPF), we
recommend you perform secondary tracking of oil exposure by using clean
(soot free) DPF weights to track ash loading and compare this mass of
ash to the amount predicted using the measured oil consumption mass and
the oil ash concentration. The ratio of the mass of ash found by DPF
weight over the predicted mass of ash based on oil consumption
measurements should fall within a range of 0.55 to 0.7.
* * * * *
(j) If you perform sulfur acceleration by increasing the sulfur
level of the burner fuel, you must meet the target sulfur level within
5 ppmw. Increase the sulfur level by adding sulfur to the
entire batch of fuel or adding sulfur to the fuel line that feeds the
burner. Verify the sulfur level of the fuel prior to the start of
aging, or whenever a new batch of aging fuel is acquired.
* * * * *
0
134. Amend Sec. 1065.1145 by revising the introductory text and
paragraphs (a), (c), and (d) to read as follows:
Sec. 1065.1145 Execution of accelerated aging, cycle tracking, and
cycle validation criteria.
The aging cycle generally consists first of practice runs to
validate and tune the final cycle, followed by the actual running of
the repeat cycles needed to accumulate field equivalent hours to reach
useful life. During the course of the aging run, various aging
parameters are tracked to allow verification of proper cycle execution,
as well as to allow for correction of the aging parameters to stay
within the target limits.
(a) Preliminary cycle validation runs. Prior to the start of aging,
conduct a number of practice runs to tune the cycle parameters. It is
recommended that initial practice runs be conducted without the
aftertreatment installed, but with the backpressure of the
aftertreatment simulated to help ensure that the tuned cycle is
representative. For final cycle tuning, including regenerations, it is
recommended to use a duplicate or spare aftertreatment system of
similar design to the target system, to avoid damage or excessive
initial aging during the tuning. However, it is permissible to conduct
final tuning using the target system being aged, but you must limit the
total duration to no more than 100 field equivalent hours (10 hours of
accelerated aging), including both thermal and chemical components. The
process followed for these initial runs will vary depending on whether
you are using an engine-based platform or a burner-based platform.
(1) Engine-based platform. (i) Initial cycle development. It will
be necessary to determine a set of engine modes that will generate the
required combinations of temperature, exhaust flow, oil consumption,
and NOX to meet the target aging requirements. The
development of these modes will be an iterative process using the
engine and independent temperature control features of the aging stand.
This process assumes that you have already implemented the oil
consumption increase modifications, and that these have already been
stabilized and validated to reach the necessary levels of bulk oil
exposure. In general, we
[[Page 43281]]
recommend the use of higher engine speeds and loads to generate the
desired oil consumption, leveraging the temperature controls as needed
to lower temperature to the targets. Several iterations will likely be
needed to reach all targets. Exhaust flow must be within 25
% of targets for individual cycle modes, and the weighted cycle average
exhaust flow (considering non-regeneration modes) must be within 10 % of the target value. Note that during transitions you may
utilize any combination of conditions necessary to help primary
component catalysts reach the target temperature and flow conditions
within no more than 5 minutes. For example, you may use a higher
exhaust flow rate and lower temperature to rapidly cool the
aftertreatment system to the next temperature. Use good engineering
judgement to select NOX targets such that the cycle-average
NOX mass rate is consistent with the application if you used
Method 1 to develop the accelerated aging cycle, and consistent with
the weighted lab cycle NOX measurements if you used Method
2. NOX targets do not need to be met during transitions. It
is permissible to deviate from engine-out NOX emission
targets if needed to reach the temperature, exhaust flow, and oil
consumption targets. We recommend that you maintain a weighted cycle
average NOX level (considering non-regeneration modes) that
is within 25 % of the target. Note that validation of oil
consumption requires at least 72 hours of operation. Tune the
parameters for infrequent regeneration towards then end of this initial
development process (such as hydrocarbon injection schedules and
temperature ramp rates).
(ii) Final cycle validation. Once the cycle is tuned, conduct a
final run using the target aftertreatment system to verify conditions
and log temperatures for heat load calculation. Using the recorded
cycle data, calculate Dt for all primary component catalysts
to ensure that you are matching the desired Dt,cycle
targets. If you are not within 3% of the target
Dt,cycle, adjust the cycle accordingly. Calculate
Dt for any secondary catalyst components to verify that they
are within 3% of either the target Dt or the
target aging metric. Note that the accelerated aging methodology
assumes that the relationship between the temperature of the primary
and secondary catalyst components will be the same as the field
observations. If this relationship deviates in the lab by having more
or less heat transfer through the system, it may be necessary to modify
that relationship on the aging stand. You may need to take measures
such as adding or removing insulation or utilize external cooling fans
to help these parameters match more closely.
(2) Burner-based platform. (i) Cycle development. The burner-based
platform should be able to meet the exhaust flow, temperature, and oil
consumption targets directly without the need for additional cycle
development. This process assumes that you have already implemented and
validated your oil consumption exposure methods to reach the necessary
levels of bulk oil exposure. Exhaust flow must be within 25% of targets for individual cycle modes, and the weighted cycle
average exhaust flow (considering non-regeneration modes) must be
within 10% of the target value. For diesel-fueled engines,
we recommend maintaining oxygen setpoints between (7 and 17) volume
percent and water setpoints between (5 and 11) volume percent. For
other fuels, use good engineering judgment to select appropriate
ranges. Use good engineering judgement to select NOX targets
such that the cycle-average NOX mass rate is consistent with
the application if you used Method 1 to develop the accelerated aging
cycle, and consistent with the weighted lab cycle NOX
measurements if you used Method 2. We recommend maintaining a weighted
cycle-average NOX level (considering non-regeneration modes)
that is within 25% of the target level. Note that during
transitions you may utilize any combination of conditions necessary to
help primary component catalysts reach the target temperature and flow
conditions within no more than 5 minutes. For example, you may use a
higher exhaust flow rate and lower temperature to rapidly cool the
aftertreatment system to the next temperature. NOX targets
do not need to be met during transitions.
(ii) Final cycle validation. Once the cycle is tuned, conduct a
final run using the target aftertreatment system to verify conditions
and log temperatures for heat load calculation. Using the recorded
cycle data, calculate Dt for all primary components
catalysts to ensure that you are matching the desired
Dt,cycle targets. If you are not within 3% of
the target Dt,cycle, adjust the cycle accordingly. Calculate
Dt for any secondary catalyst components to check that they
are within 3% of either the target Dt or the
target aging metric. Note that the accelerated aging methodology
assumes that the relationship between the temperature of the primary
and secondary catalyst components will be the same as that observed in
the field. If this relationship deviates in the lab by having more or
less heat transfer through the system, it may be necessary to modify
that relationship on the aging stand. You may need to take measures
such as adding or removing insulation or utilize external cooling fans
to help these parameters match more closely.
* * * * *
(c) Initial emission testing. Prior to the start of accelerated
aging conduct the initial zero-hour emission test and any required
engine dynamometer aging following the requirements of the standard
setting part for your engine. Dynamometer aging hours count toward the
total aging hours.
(d) Accelerated aging. Following zero-hour emission testing and any
engine dynamometer aging, perform accelerated aging using the cycle
validated in either paragraph (a)(1) or (2) of this section. Repeat the
cycle the number of times required to reach useful life equivalent
aging. Interrupt the aging cycle as needed to conduct any scheduled
intermediate emission tests, clean the DPF of accumulated ash, and for
any facility-related reasons. We recommend you interrupt aging at the
end of a given aging cycle, following the completion of any scheduled
infrequent regeneration event. If an aging cycle is paused for any
reason, we recommend that you resume the aging cycle at the same point
in the cycle where it stopped to ensure consistent thermal and chemical
exposure of the aftertreatment system.
* * * * *
0
135. Amend subpart L by adding a new center header following Sec.
1065.1145 and adding Sec. Sec. 1065.1147, 1065.1149, 1065.1151,
1065.1153, and 1065.1155 under that center header to read as follows:
Accelerated Aftertreatment Aging--Spark-Ignition Aftertreatment
Sec. 1065.1147 General provisions related to accelerated aging of
spark-ignition aftertreatment for deterioration factor determination.
Sections 1065.1147 through 1065.1155 specify procedures for spark-
ignition engine aftertreatment systems to produce an aged
aftertreatment system, in an accelerated fashion, for durability
demonstration. Determine the target number of hours that represents
useful life for an engine family as described in the standard setting
part. The method described is a procedure for translating field data
that represents a given application into an accelerated aging cycle for
that specific application, as well as methods for carrying out aging
using that cycle. The procedure is intended to be representative of
field
[[Page 43282]]
aging and includes exposure to elements of both thermal and chemical
aging.
Sec. 1065.1149 Standard catalyst bench-aging procedure.
This section provides a means to accelerate aging of the catalyst-
plus-oxygen-sensor system on a catalyst aging bench. Accelerated aging
is performed by testing the system over the standard bench cycle (SBC)
based on the calculated bench aging time, BAT, which uses catalyst
time-at-temperature data measured from field data over a cycle you
develop or over the standard road cycle (SRC) provided in Table 1 and
Figure 1 of this section. You may develop your own method to calculate
bench aging with our approval. Demonstrate that your bench aging
calculations provide the same or larger amount of emission
deterioration as the standard bench aging procedure.
Table 1 of Sec. 1065.1149--Standard Road Cycle (SRC) \a\ \b\
------------------------------------------------------------------------
Typical accel
Lap Description rate (mi/hr/s)
------------------------------------------------------------------------
1....................... (start engine) Idle 10 sec.... 0
1....................... Moderate acceleration to 30 mi/ 4
hr.
1....................... Cruise at 30 mi/hr for \1/4\ 0
lap.
1....................... Moderate deceleration to 20 mi/ -5
hr.
1....................... Moderate acceleration to 30 mi/ 4
hr.
1....................... Cruise at 30 mi/hr for \1/4\ 0
lap.
1....................... Moderate deceleration to stop. -5
1....................... Idle for 5 seconds............ 0
1....................... Moderate acceleration to 35 mi/ 4
hr.
1....................... Cruise at 35 mi/hr for \1/4\ 0
lap.
1....................... Moderate deceleration to 25 mi/ -5
hr.
1....................... Moderate acceleration to 35 mi/ 4
hr.
1....................... Cruise at 35 mi/hr for \1/4\ 0
lap.
1....................... Moderate deceleration to stop. -5
2....................... Idle 10 sec................... 0
2....................... Moderate acceleration to 40 mi/ 3
hr.
2....................... Cruise at 40 mi/hr for \1/4\ 0
lap.
2....................... Moderate deceleration to 30 mi/ -5
hr.
2....................... Moderate acceleration to 40 mi/ 3
hr.
2....................... Cruise at 40 mi/hr for \1/4\ 0
lap.
2....................... Moderate deceleration to stop. -5
2....................... Idle for 5 seconds............ 0
2....................... Moderate acceleration to 45 mi/ 3
hr.
2....................... Cruise at 45 mi/hr for \1/4\ 0
lap.
2....................... Moderate deceleration to 35 mi/ -5
hr.
2....................... Moderate acceleration to 45 mi/ 3
hr.
2....................... Cruise at 45 mi/hr for \1/4\ 0
lap.
2....................... Moderate deceleration to stop. -5
3....................... Idle 10 sec................... 0
3....................... Hard acceleration to 55 mi/hr. 4
3....................... Cruise at 55 mi/hr for \1/4\ 0
lap.
3....................... Moderate deceleration to 45 mi/ -5
hr.
3....................... Moderate acceleration to 55 mi/ 2
hr.
3....................... Cruise at 55 mi/hr for \1/4\ 0
lap.
3....................... Moderate deceleration to 45 mi/ -5
hr.
3....................... Moderate acceleration to 60 mi/ 2
hr.
3....................... Cruise at 60 mi/hr for \1/4\ 0
lap.
3....................... Moderate deceleration to 50 mi/ -5
hr.
3....................... Moderate acceleration to 60 mi/ 2
hr.
3....................... Cruise at 60 mi/hr for \1/4\ 0
lap.
3....................... Moderate deceleration to stop. -4
4....................... Idle 10 sec................... 0
4....................... Hard acceleration to 80 mi/hr. 3
4....................... Coastdown to 70 mi/hr......... -1
4....................... Cruise at 70 mi/hr for \1/2\ 0
lap.
4....................... Moderate deceleration to 50 mi/ -3
hr.
4....................... Moderate acceleration to 65 mi/ 2
hr.
4....................... Cruise at 65 mi/hr for \1/2\ 0
lap.
4....................... Moderate deceleration to 50 mi/ -3
hr.
5....................... Moderate acceleration to 75 mi/ 1
hr.
5....................... Cruise at 75 mi/hr for \1/2\ 0
lap.
5....................... Moderate deceleration to 50 mi/ -3
hr.
5....................... Light acceleration to 70 mi/hr 1
5....................... Cruise at 70 mi/hr for \1/2\ 0
lap.
5....................... Moderate deceleration to 50 mi/ -3
hr.
6....................... Moderate acceleration to 70 mi/ 2
hr.
6....................... Coastdown to 60 mi/hr......... -1
6....................... Cruise at 60 mi/hr for \1/2\ 0
lap.
6....................... Moderate deceleration to 50 mi/ -4
hr.
6....................... Moderate acceleration to 65 mi/ 1
hr.
6....................... Cruise at 65 mi/hr for \1/2\ 0
lap.
[[Page 43283]]
6....................... Moderate deceleration to stop. -4
7....................... Idle 45 sec................... 0
7....................... Hard acceleration to 55 mi/hr. 4
7....................... Cruise at 55 mi/hr for \1/4\ 0
lap.
7....................... Moderate deceleration to 40 mi/ -5
hr.
7....................... Moderate acceleration to 55 mi/ 2
hr.
7....................... Cruise at 55 mi/hr for \1/4\ 0
lap.
7....................... Moderate deceleration to 40 mi/ -5
hr.
7....................... Moderate acceleration to 50 mi/ 2
hr.
7....................... Cruise at 50 mi/hr for \1/4\ 0
lap.
7....................... Moderate deceleration to 40 mi/ -5
hr.
7....................... Moderate acceleration to 50 mi/ 2
hr.
7....................... Cruise at 50 mi/hr for \1/4\ 0
lap.
7....................... Moderate deceleration to stop. -5
------------------------------------------------------------------------
\a\ The engine may be run in a vehicle on a track or on a mileage
accumulation dynamometer.
\b\ The cycle consists of 7 laps of a 3.7-mile course. The length of the
lap may be changed to accommodate the length of the service-
accumulation track.
[GRAPHIC] [TIFF OMITTED] TP14JY26.106
(a) Standard bench cycle (SBC). Perform standard catalyst bench
aging by following the SBC, as described in Sec. 1065.1153.
(b) Catalyst time-at-temperature data. (1) Measure the catalyst
temperature over at least two full cycles of the SRC or use temperature
data acquired in the field to obtain your catalyst time-at-temperature.
(2) Measure the catalyst bed temperature at the highest peak
temperature location in the hottest catalyst on the vehicle or engine
as described in Sec. 1065.1155(f). We recommend using thermocouples
that are 1.6 mm in diameter to ensure fast response to temperature
changes. Alternatively, the temperature may be measured at another
location providing that it is adjusted to represent the temperature
measured at the hottest location using good engineering judgement.
(3) Measure the catalyst temperature at a minimum of 1 Hz.
[[Page 43284]]
(4) Use the measured catalyst temperature results to generate a
histogram with temperature bins of no larger than 25 [deg]C.
(c) Bench-aging time. Determine bench aging time, BAT, using the
following series of equations:
(1) Determine the equivalent catalyst aging time,
te,bin, at the effective reference temperature,
Tr, on the catalyst aging bench using the catalyst aging
cycle to produce the same amount of deterioration experienced by the
catalyst due to thermal deactivation at the temperature bin,
Tv, over the vehicle's useful life.
[GRAPHIC] [TIFF OMITTED] TP14JY26.107
Where:
th = time measured within the prescribed temperature bin
of the vehicle's catalyst temperature histogram adjusted to a full
useful life basis, in hours. For example, if the histogram
represented 400 miles, and full useful life was 100,000 miles; all
histogram time entries would be multiplied by 250 (100,000/400).
R = catalyst thermal reactivity coefficient = 17,500 for the SBC.
You may optionally develop your own coefficient using the procedure
described in Sec. 1065.1151.
Tr = the effective reference temperature of the catalyst
on the catalyst bench run on the bench aging cycle, in [deg]K. The
effective temperature is the constant temperature that would result
in the same amount of aging as the various temperatures experienced
during the bench aging cycle.
Tv = the mid-point temperature of the temperature bin of
the vehicle or engine catalyst temperature histogram, in [deg]K.
(2) Determine the equivalent time to age the catalyst at the
temperature of Tr on the catalyst aging bench using the
catalyst aging cycle, te,total. This equivalent time is
determined by summing the time for all temperature bin results from Eq.
1065.1149-1 which will result in the same amount of deterioration
experienced by the catalyst due to thermal deactivation over the
vehicle's full useful life.
[GRAPHIC] [TIFF OMITTED] TP14JY26.108
Where:
n = total number of temperature bins.
i = an indexing variable that represents one temperature bin.
(3) Determine BAT.
[GRAPHIC] [TIFF OMITTED] TP14JY26.109
Where:
A = catalyst aging adjustment time to account for deterioration from
sources other than thermal aging of the catalyst = 1.1. You may
develop your own adjustment factor using good engineering judgement,
without prior EPA approval, to ensure that the durability process
will achieve the durability objective of Sec. 1065.1147. You may
account for chemical aging using fuel with additional compounds that
may lead to catalyst poisoning, such as phosphorus, sulfur or lead.
If you choose this option, you must calculate a new, A, and ensure
that the durability objective of this section is achieved.
(d) Effective reference temperature on the SBC. Determine the
effective reference temperature of the standard bench cycle (SBC) for
the actual catalyst system design and actual aging bench used, using
the following procedures:
(1) Measure the catalyst system time-at-temperature while being
tested on the catalyst aging bench over the SBC.
(i) Measure catalyst temperature at the highest peak temperature
location of the hottest catalyst in the system. Alternatively, the
temperature may be measured at another location providing that it is
adjusted to represent the temperature measured at the hottest location
using good engineering judgement.
(ii) Measure catalyst temperature at 1 Hz for at least 20 minutes
of bench aging cycle.
(iii) Use the measured catalyst temperature results to generate a
histogram with temperature bins of no larger than 10 [deg]C.
(2) Use Eq. 1065.1149-1 to iteratively calculate the effective
reference temperature by changing the reference temperature,
Tr, until the calculated aging time equals the actual time
represented in the catalyst temperature histogram. The resulting
temperature is the effective reference temperature on the SBC for that
catalyst system and aging bench.
(e) Catalyst aging bench. Use good engineering judgement to design
a catalyst aging bench that follows the SBC and delivers the
appropriate exhaust constituents and exhaust temperature to the face of
the catalyst. Use good engineering judgment to select an appropriate
exhaust flow. Good engineering judgment would include selecting an
exhaust flow equal to the average exhaust flow over the road cycle,
within 10%.
(1) Design your catalyst aging bench as described in Sec.
1065.1155. You may use another design that results in equivalent or
superior results with our prior approval.
(2) Design your catalyst aging bench to record appropriate
information such as lambda and catalyst time-at-temperature to ensure
that sufficient aging has occurred.
Sec. 1065.1151 Experimentally determining the catalyst thermal
reactivity coefficient (R) for bench aging durability procedures.
If you choose not to use the default catalyst thermal reactivity
coefficient that follows in Eq. 1065.1149-1, experimentally determine
the coefficient using the following procedure:
(a) Use the applicable bench cycle and aging bench hardware to age
at least three catalysts at different control temperatures ranging
between the normal operating temperature and the damage limit
temperature. Measure emissions during this aging for all regulated
pollutants. Ensure that the final testing yields emission data between
one- and two-times the standard.
(b) Estimate the catalyst thermal reactivity coefficient and
calculate the effective reference temperature, Tr, for the
bench aging cycle for each control temperature according to the
procedure described in Sec. 1065.1149(d).
(c) Generate a plot of emissions (or catalyst inefficiency) versus
aging time for each catalyst. Calculate the least-squared best-fit line
through the data. The data should have a common intercept between 0 and
4000 miles. The following figure provides an example of the plot:
[[Page 43285]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.110
(d) Calculate the slope of the best-fit line for each aging
temperature.
(e) Plot the natural log (ln) of the slope of each best-fit line
determined in paragraph (d) of this section along the vertical axis,
versus the inverse of aging temperature (1/(aging temperature, [deg]K))
along the horizontal axis. Calculate the least-squared best-fit lines
through the data. The slope of the line is the catalyst thermal
reactivity coefficient. The following figure provides an example of the
plot:
[[Page 43286]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.111
(f) Compare the catalyst thermal reactivity coefficient to the
initial value that was used in paragraph (b) of this section. If the
calculated catalyst thermal reactivity coefficient differs from the
initial value by more than 5%, choose a new coefficient that is between
the initial and calculated values, then repeat the steps in paragraphs
(b) through (f) of this section to derive a new coefficient. Repeat
this process until the calculated catalyst thermal reactivity
coefficient is within 5% of the initially assumed coefficient.
(g) Compare the catalyst thermal reactivity coefficient determined
separately for each constituent. Use the lowest catalyst thermal
reactivity coefficient for calculating BAT.
Sec. 1065.1153 Standard bench cycle (SBC).
The standard bench aging durability procedure consists of aging a
catalyst-oxygen-sensor system on an aging bench that follows the SBC.
(a) The SBC requires use of an aging bench (exhaust gas generator)
with an engine or burner as the source of feed gas for the catalyst.
(b) The SBC is a 60-second cycle which is repeated on the aging
bench for the duration of the procedure. The SBC is defined based on
the duration of a given operating mode and associated catalyst bed
temperature, exhaust lambda, and the amount of secondary air injection
added upstream of the catalyst. Maintain the exhaust flow rate as
described in Sec. 1065.1149(e). You may develop and use your own bench
cycle with our approval. Demonstrate that your bench cycle provides the
same or a larger amount of emission deterioration as the standard bench
cycle.
(c) Instrument the catalyst to measure the bed temperature at the
location where the highest peak bed temperature occurs in the hottest
catalyst. Alternatively, measure the feed gas temperature and convert
it to catalyst bed temperature using a linear transform calculated from
correlation data collected on the catalyst design and aging bench used
in the aging process.
(d) Control the catalyst bed temperature at stoichiometric
conditions (Mode 1), Tlambda1, to a minimum of 800 [deg]C
(10 [deg]C) by selecting the appropriate operating
conditions (fueling and air flow) for the aging bench. Note that the
catalyst bed temperature might be out of tolerance in Mode 1 initially
after the transition from Mode 4. Control the maximum catalyst
temperature that occurs during the cycle, Tlambdarich, to
890 [deg]C (10 [deg]C) by selecting the appropriate aging
bench lambda during the ``rich'' phase described in the table below.
Note that the temperatures given in this paragraph are based on neat
(E0) gasoline and the temperatures will change with fuel type.
(e) If a Mode 1 target catalyst bed temperature other than 800
[deg]C is utilized, set the high control temperature to 90 [deg]C
greater than the Mode 1 catalyst bed temperature.
Table 1 of Sec. 1065.1153--Standard Bench Cycle (SBC)
----------------------------------------------------------------------------------------------------------------
Secondary air
Mode Time (seconds) Aging bench operating conditions injection
----------------------------------------------------------------------------------------------------------------
1.................................. 1-40 Lambda = 1 with operating conditions None.
set to achieve the targeted
catalyst bed temperature (typically
a minimum of 800 [deg]C) and
exhaust flow rate.
[[Page 43287]]
2.................................. 41-45 Same as Mode 3...................... None.
3.................................. 46-55 ``Rich'' (lambda selected to achieve 3% (0.1%).
the entire cycle of 890 [deg]C, or
90 [deg]C higher than low control
temperature).
4.................................. 56-60 Same as Mode 1...................... 3% (0.1%).
----------------------------------------------------------------------------------------------------------------
[GRAPHIC] [TIFF OMITTED] TP14JY26.112
Sec. 1065.1155 Aging bench equipment and procedures.
This section provides specifications for the standard aging bench
equipment and aging procedures used to conduct catalyst bench aging
under the provisions of Sec. 1065.1147.
(a) Design the aging bench to provide the appropriate temperature,
lambda, exhaust constituents and secondary air injection at the inlet
face of the catalyst. Maintain the exhaust flow rate as described in
Sec. 1065.1149(e).
(b) The standard aging bench consists of an engine, engine
controller, and engine dynamometer. You may use other configurations,
such as a burner that provides the correct exhaust conditions, as long
as the catalyst inlet conditions and control features specified in this
section are met. You may split the exhaust flow into multiple streams
to simultaneously age multiple catalyst systems.
(c) Use the appropriate fuel specified in Sec. Sec. 1065.710(b),
1065.715, or 1065.720. Use good engineering judgment to select a
representative commercial oil to use in the engine.
(d) Install the entire catalyst(s)-plus-oxygen-sensor(s) system,
together with all exhaust piping which connects these components, on
the bench. Install each bank of the exhaust system separately on the
bench for engines with multiple exhaust streams. You may request
approval to age the oxygen sensor system separately.
(e) Install the entire catalyst system as a unit for aging;
including all catalysts, all oxygen sensors (if not aged separately)
and the associated exhaust piping for exhaust systems that contain
multiple in-line catalysts. You may shorten the distance between the
emission source and catalyst as needed to accommodate installation.
Alternatively, each individual catalyst may be separately aged for the
appropriate period of time.
(f) Measure catalyst temperature using a thermocouple placed in the
catalyst bed at the location where the highest peak temperature occurs
in the hottest catalyst. We recommend using thermocouples that are 1.6
mm in diameter to ensure fast response to temperature changes. Record
catalyst temperature at 1 Hz during the aging procedure.
(g) Measure lambda as close as possible to the catalyst inlet
flange at 1 Hz during the aging procedure.
(h) Maintain exhaust flow rate as described in Sec. 1065.1149(e).
Determine proper flow rate based upon the exhaust flow that would occur
at the engine's steady state speed and load selected for
[[Page 43288]]
the bench aging in paragraph (i) of this section.
(i) Set the engine speed, load, and spark timing to achieve a
catalyst bed temperature of 800 10 [deg]C at steady-state
stoichiometric operation.
(j) Set the air injection system to produce 3.0 0.3%
oxygen in the steady-state stoichiometric exhaust stream. Use good
engineering judgment to locate the secondary air injection point at a
position upstream of the catalyst to ensure well mixed exhaust. A
typical reading at the upstream measurement point is lambda 1.16, which
equates to approximately 3% oxygen. Measure the oxygen concentration
resulting from the secondary air injection (10 to 20) mm downstream of
the secondary air injection point.
(k) Set the ``Rich'' lambda, with the air injection on, to produce
a catalyst bed temperature of 890 10 [deg]C. A typical
lambda value for this step is 0.94, which equates to approximately 2%
CO.
(l) The standard bench aging procedure uses the SBC in Sec.
1065.1153. Repeat the SBC until the amount of aging calculated from Eq.
1065.1149-3 is achieved.
(m) Periodically verify the temperature, lambda, and exhaust flow
rate values from paragraphs (f), (g), and (h) of this section at least
every 50 hours during aging. Make adjustments as necessary to ensure
that the SBC is properly followed throughout the aging process.
(n) Once the aging cycle is complete, generate a histogram of the
catalyst time-at-temperature from the data collected during the aging
process with temperature bins of no larger than 10 [deg]C. Verify that
the appropriate amount of thermal aging of the catalyst occurred using
the BAT value from Eq. 1065.1149-3 and the calculated effective
reference temperature for the aging cycle from Sec. 1065.1149(d).
Extend the bench aging if the thermal effect of the calculated aging
time is not at least 95% of the target thermal aging.
(o) Use special low temperature startup and shutdown procedures to
ensure that the maximum catalyst temperature for rapid deterioration
(e.g., 1050 [deg]C) does not occur.
0
136. A new part 1071 is added to subchapter U of chapter I to read as
follows:
PART 1071--NONCONFORMANCE PENALTIES
Subpart A--Program Overview
1071.1 Applicability and general provisions.
1071.5 Criteria for adopting nonconformance penalties.
1071.10 Establishing Upper Limits.
1071.15 Qualifying for nonconformance penalties.
Subpart B--Compliance Provisions
1071.30 General provisions for Production Compliance Audits.
1071.35 Maintenance and testing procedures for Production Compliance
Audits.
1071.40 Determining the Compliance Level.
1071.45 Fail thresholds.
1071.50 Test reporting.
1071.55 Recordkeeping.
1071.60 EPA testing.
1071.65 Labeling.
Subpart C--Penalty Provisions
1071.80 Penalty parameters for specific standards.
1071.85 Calculating the nonconformance penalty.
1071.90 Making payments.
Subpart D--Administrative Provisions
1071.100 Entry and access.
1071.105 Suspending and voiding certificates of conformity.
1071.110 Hearing procedures.
1071.115 Confidential information.
1071.120 List of acronyms.
Appendix A to Part 1071--Penalty Parameter Values for Historical
Standards
Authority: 42 U.S.C. 7401-7671q.
Subpart A--Program Overview
Sec. 1071.1 Applicability and general provisions.
(a) This part describes how nonconformance penalties apply for
qualifying motor vehicles and motor vehicle engines. Nonconformance
penalties allow manufacturers to produce vehicles or engines that do
not meet new emission standards, with the penalty designed to avoid a
competitive advantage from producing higher-emitting vehicles or
engines.
(b) Nonconformance penalties may apply relative to new standards
that apply for motor vehicles above 6,000 pounds GVWR and for engines
that will be installed in such vehicles. Nonconformance penalties apply
for specific emission standards and for specific classes of vehicles
and engines as specified in this part. We may establish nonconformance
penalties by dividing vehicles into classes based on any relevant
parameters.
(c) Participating manufacturers determine a Compliance Level to
characterize the level of emission control as described in subpart B of
this part. The amount of the penalty is calculated by comparing the
Compliance Level to the published emission standard as described in
subpart C of this part. The Compliance Level also serves as the
emission standard for compliance testing with individual vehicles or
engines.
(d) Unless we specify otherwise, send all reports and requests for
approval to the Designated Compliance Officer (see 40 CFR 1068.30). See
Sec. Sec. 1071.50 and 1071.55 for specific reporting and recordkeeping
provisions.
(e) All terms in this part have the meaning given in the Clean Air
Act (42 U.S.C. 7401-7671q). The following conventions and definitions
apply for this part:
(1) The term ``you'' means the manufacturer certifying vehicles or
engines with nonconformance penalties as specified in this part.
(2) References to ``NCP families'' are understood to include engine
families for engine-based exhaust emission standards for vehicle-based
evaporative and refueling emission standards. References to ``NCP
families'' are also understood to include test groups and durability
groups for vehicle-based exhaust emission standards.
(3) Good engineering judgment has the meaning given in 40 CFR
1068.30.
(4) Round has the meaning given in 40 CFR 1065.1001.
(5) Configuration has one of the following meanings:
(i) For vehicle-based standards, configuration has the meaning
given for ``vehicle configuration'' in 40 CFR 86.1803-01.
(ii) For engine-based standards, configuration has the meaning
given for ``engine configuration'' in 40 CFR 1036.801.
Sec. 1071.5 Criteria for adopting nonconformance penalties.
We will determine whether nonconformance penalties are appropriate
for a given emission standard for a given class of vehicles or engines
as described in this section based on our evaluation of criteria
designed to assess the likelihood that a manufacturer will be
technologically unable to meet the emission standard on time.
(a) Criteria. We will establish a nonconformance penalty if the
following three criteria apply:
(1) There is a new emission standard. The new emission standard may
result from adopting a standard that is more stringent than what we
adopted previously. An existing emission standard might also be
considered new if meeting that standard becomes more difficult because
of a new or revised standard for a different pollutant. An emission
standard is no longer new under this paragraph (a)(1) when all
manufacturers already producing U.S.-directed vehicles or engines
within the
[[Page 43289]]
class comply with the standard without using emission credits.
(2) Meeting the relevant standard requires (or required)
application of new technology or significant modification of existing
technology, as evaluated from the point at which we adopted the new
standard (or from the point at which we adopted an emission standard
for a different pollutant that made it more difficult to meet the
relevant standard).
(3) There is a manufacturer that is unable, or will likely be
unable, for technological reasons to meet the emission standard for one
or more vehicle or engine models within the class.
(b) Evaluation. We will evaluate the criteria in paragraph (a) of
this section based on any available information. We will not establish
a nonconformance penalty if we determine that any of the specified
criteria do not apply. We may establish a nonconformance penalty if we
determine that the criterion in paragraph (a)(3) applies even if we are
uncertain whether one or both criteria in paragraphs (a)(1) and (2)
apply. If we determine that a manufacturer will fail to meet a
standard, we may establish a nonconformance penalty even if we are not
certain that the failure is for technological reasons.
Sec. 1071.10 Establishing Upper Limits.
A vehicle or engine you certify with a nonconformance penalty must
have a Compliance Level that is at or below an Upper Limit that we
establish by rulemaking. This section describes how we establish the
Upper Limit.
(a) The Upper Limit will generally be the previous emission
standard. We may select a more stringent Upper Limit if we determine
that all the vehicles or engines in the class can meet the more
stringent Upper Limit. Conversely, we may select an appropriately less
stringent Upper Limit if we determine that not all the vehicles or
engines in the class can meet the previous standard.
(b) The following provisions apply for carryover NCP families
certified to the relevant emission standard with a Family Emission
Limit:
(1) Except as specified in paragraph (b)(2) of this section, if the
Family Emission Limit is above the previous emission standard, we may
set the Upper Limit for that NCP family to be equal to the Family
Emission Limit.
(2) If the Upper Limit under paragraph (a) of this section is more
stringent than the previous emission standard, the Upper Limit for the
carryover NCP family is the previous emission standard.
(c) We will set an appropriate Upper Limit if there is no previous
standard, or if the nonconformance penalty is based on an existing
standard becoming more difficult because of a new or revised standard
for a different pollutant.
Sec. 1071.15 Qualifying for nonconformance penalties.
This section describes how you may produce vehicles or engines that
comply using nonconformance penalties under this part in spite of
exceeding an emission standard.
(a) Nonconformance penalties are available for the following
standards and classes of vehicles or engines:
(1) Medium HDE subject to the 35 mg/hp[sdot]hr NOX
standard in 40 CFR 1036.104.
(2) Heavy HDE subject to the 35 mg/hp[sdot]hr NOX
standard in 40 CFR 1036.104.
(b) Vehicles and engines you certify using nonconformance penalties
must be in their own engine family or test group. We refer to these
separately certified groups of vehicles and engines as NCP families.
Vehicles and engines you certify using emission credits are not
eligible for nonconformance penalties.
(c) You are eligible to produce vehicles or engines with a
Compliance Level up to the Upper Limit as described in this section in
either of the following circumstances:
(1) Your application for certification has a certified emission
level that exceeds an emission standard identified in paragraph (a) of
this section, but it is at or below the associated Upper Limit. Note
that this may occur if you otherwise would need to amend an existing
application for certification to include a new or modified
configuration that has a certified emission level that exceeds an
emission standard identified in paragraph (a) of this section.
(2) One of your test groups or engine families fails a Selective
Enforcement Audit under 40 CFR part 86, subpart G, or part 1068,
subpart E, with respect to a standard identified in paragraph (a) of
this section.
(d) The following requirements apply with respect to vehicles and
engines qualifying for nonconformance penalties under this part:
(1) You must establish a Compliance Level as described in subpart B
of this part that is at or below the Upper Limit. You must also send us
test results and keep records associated with Production Compliance
Audits, as applicable.
(3) You must label vehicles or engines as described in Sec.
1071.65.
(4) You must make timely payments as described in Sec. Sec.
1071.85 and 1071.90.
Subpart B--Compliance Provisions
Sec. 1071.30 General provisions for Production Compliance Audits.
Unless otherwise specified in Sec. 1071.80, the Compliance Level
for establishing a per-vehicle or per-engine nonconformance penalty
under this part is based on test results from Production Compliance
Audits. Paragraphs (a) and (b) of this section describe administrative
and procedural provisions that apply for two different scenarios.
(a) You may start to produce vehicles or engines with a certified
emission level exceeding an emission standard as described in Sec.
1071.15(c)(1) under a certificate of conformity that is subject to the
following conditions:
(1) You must agree to conduct a Performance Compliance Audit as
described in Sec. 1071.35. The Compliance Level from the tested
configurations applies for the whole NCP family unless we approve your
proposed approach to test additional configurations and divide
different configurations across the NCP family into subfamilies based
on similar emission characteristics for establishing different
Compliance Levels.
(2) You must agree to pay the nonconformance penalty resulting from
the Production Compliance Audit for each affected vehicle or engine you
produce, subject to the hearing provisions in Sec. 1071.110.
(3) You must agree to meet recall requirements for all affected
configurations with a Compliance Level that exceeds the Upper Limit.
Recall requirements are in 40 CFR part 85, subpart S, for vehicles and
in 40 CFR part 1068, subpart F, for engines. Recall requirements apply
without a separate EPA determination under 40 CFR 85.1802(a) or
1068.505(a).
(4) You must start to select and test vehicles or engines within
five days after you start to produce affected vehicles or engines,
unless we agree to allow additional time.
(5) If the Production Compliance Audit results in a Compliance
Level at or below the emission standard, you may produce vehicles or
engines for all affected configurations under the existing certificate
of conformity and the conditions in paragraph (a)(2) and (3) of this
section do not apply.
(6) You may add a configuration to an NCP family certified with
nonconformance penalties or change a configuration already included in
the NCP family by amending your application for certification as
described in 40 CFR 86.1842-01 for vehicles and for engines as
described in 40 CFR
[[Page 43290]]
1036.225 for engines, subject to the following conditions:
(i) If the existing Compliance Level continues to be appropriate
for the new or changed configuration, you may treat those vehicles or
engines like the others in the NCP family.
(ii) If your new or changed configuration fully complies with
current emission standards, you may certify those vehicles or engines
in a separate family that is not subject to nonconformance penalties.
(iii) You may perform a Production Compliance Audit as described in
Sec. 1071.35 with vehicles or engines in the new or changed
configuration (or configurations) to establish a Compliance Level. If
the Compliance Level for the new or changed configuration is lower than
the earlier Compliance Level but still does not meet current emission
standards, you may include affected vehicles or engines in a new
subfamily that uses the new Compliance Level.
(b) If a vehicle or engine family fails a Selective Enforcement
Audit as described in Sec. 1071.15(c)(2), you may establish an NCP
family and continue to produce vehicles or engines from the NCP family,
subject to the following conditions:
(1) Within five days after you conclude the Selective Enforcement
Audit, send us a written report describing your plan to conduct a
Production Compliance Audit, including the date you will start testing.
If the Selective Enforcement Audit was conducted on an engine family
with a certified emission level at or below emission standards, state
that you intend to continue production without making changes to remedy
the nonconformity while you conduct a Production Compliance Audit.
(2) You must agree to pay the Nonconformance Penalty resulting from
the Production Compliance Audit for each affected vehicle or engine you
produce, subject to the hearing provisions in Sec. 1071.110.
(3) You must agree to meet recall requirements as described in
paragraph (a)(3) of this section.
(4) You must select vehicles or engines for the Production
Compliance Audit that you produced with the same configuration (or
configurations) as you tested in the Selective Enforcement Audit.
Unless we instruct otherwise, the provisions of the test order for the
Selective Enforcement Audit apply equally for the Production Compliance
Audit.
(5) You must start to select and test vehicles or engines within
ten days after you conclude the Selective Enforcement Audit, unless we
agree to allow additional time.
(6) Include measured values from the Selective Enforcement Audit
along with test results from the Production Compliance Audit to
determine the Compliance Level under Sec. 1071.40.
(7) If the Selective Enforcement Audit was conducted on a vehicle
family or engine family already subject to a Nonconformance Penalty and
the Production Compliance Audit results in a Compliance Level at or
below the emission standard, you no longer need to pay Nonconformance
Penalties for vehicles or engines demonstrated to meet emission
standards.
(c) You are disqualified from pursuing nonconformance penalties
under this part if you fail to meet a deadline to start testing or if
you fail to meet a deadline to send us a report after concluding a
Selective Enforcement Audit, unless you convince us that the delay was
justified. You are similarly disqualified from establishing a reduced
Compliance Level under paragraph (b) of this section if you fail to
meet a deadline to start testing or if you fail to meet a deadline to
send us a report after concluding a Selective Enforcement Audit.
Sec. 1071.35 Maintenance and testing procedures for Production
Compliance Audits.
(a) If you perform a Production Compliance Audit, we will send you
instructions that are analogous to a test order for a Selective
Enforcement Audit under 40 CFR part 1068, subpart E. Testing will
generally require that you measure emissions of all regulated
pollutants.
(b) Select and prepare vehicles or engines for testing as described
in 40 CFR 1068.410. Our test order will address selection criteria for
establishing a test sample that properly represents the NCP family.
(c) Test vehicles or engines as described in 40 CFR 1068.415;
however, for vehicle testing, the default minimum testing rate is four
vehicles per day. Measurements generally involve testing vehicles as
described in 40 CFR part 86, subpart S, and 40 CFR part 1066, and
testing engines as described in 40 CFR part 1036, subpart F, and 40 CFR
part 1065.
(d) You must take all necessary steps to complete the audit without
delay.
(e) You may ship a tested vehicle or engine before establishing the
Compliance Level under Sec. 1071.40 only if it has deteriorated
emission results at or below applicable emission standards. You may not
retest any vehicle or engine after you ship it.
Sec. 1071.40 Determining the Compliance Level.
Determine the Compliance Level for the NCP family based on test
results from a sample of vehicles or engines as described in this
section. You may select a Compliance Level above the value you
determine from testing under this section, as long as it is below the
Upper Limit.
(a) Establish final deteriorated test results for each tested
vehicle or engine as follows:
(1) The initial test result is the measured value from testing for
comparing to the standard as described in Sec. 1071.35. Determine the
final test result by summing the initial test results from all the
tests for a given vehicle or engine, dividing by the number of tests,
and rounding to one more decimal place than the applicable standard.
(2) Apply the NCP family's multiplicative or additive deterioration
factor to the final test result, along with any infrequent regeneration
adjustment factors from your application for certification, to
determine the final deteriorated test result. Round the final
deteriorated test results to the same number of decimal places as the
applicable standard.
(b) The Compliance Level is intended to represent the 60th
percentile deteriorated emission level for a population. Except as
specified in paragraph (c) of this section, determine the Compliance
Level using the following primary sampling and calculation method:
(1) Determine final deteriorated test results for at least 24
vehicles or engines. If the Production Compliance Audit follows an NCP
family failing a Selective Enforcement Audit, consider all the tests
from the Selective Enforcement Audit to be part of the Production
Compliance Audit under this paragraph (b); you must conduct additional
testing for the Production Compliance Audit only as needed to test 24
vehicles or engines.
(2) Arrange the final deteriorated test results from all test
vehicles or engines from the lowest to the highest value. Determine the
Compliance Level based on the 60th percentile deteriorated emission
level as follows:
(i) If there were exactly 24 test vehicles or engines, the
Compliance Level is the final deteriorated test result for vehicle or
engine number 15 in the sequence (where engine number 1 has the lowest
final deteriorated test result).
(ii) If there were more than 24 test vehicles or engines, multiply
the total number of test vehicles or engines by 0.6 and express the
result as a ceiling function to the nearest whole number.
[[Page 43291]]
For example, the Compliance Level is the final deteriorated test result
for vehicle or engine number 17 in the sequence if the total number of
test vehicles or engines is either 27 (27 x 0.6 = 16.2) or 28 (28 x 0.6
= 16.8).
(c) You may determine the Compliance Level based on either of the
alternative sampling methods for reduced testing in paragraph (c)(1) or
(2) of this section. You may start with an alternative sampling method
and expand your testing to instead determine the Compliance Level based
on testing at least 24 vehicles or engines as described in paragraph
(b) of this section. If the Production Compliance Audit follows an NCP
family failing a Selective Enforcement Audit, consider all the tests
from the Selective Enforcement Audit to be part of the Production
Compliance Audit under this paragraph (c).
(1) The fixed reduced sampling plan applies as follows:
(i) Select at least three and up to 23 vehicles or engines for
testing.
(ii) Calculate the Compliance Level, CL, based on the cumulative
sample of tested vehicles or engines using the following equation,
rounding the result to the same number of decimal places as the
emission standard:
[GRAPHIC] [TIFF OMITTED] TP14JY26.113
Where:
e= The arithmetic mean of final deteriorated test results from the
set of tested vehicles or engines. See 40 CFR 1065.602(b).
k = A constant based on the size of the test sample, as shown in
paragraph (c)(4) of this section for fixed reduced sampling.
s = The standard deviation of the final deteriorated test results
from the set of tested vehicles or engines. See 40 CFR 1065.602(c).
(iii) You may increase the sample size by any number of vehicles or
engines, up to the maximum of 23, to recalculate the Compliance Level.
(2) The sequential reduced sampling plan applies as follows:
(i) Select a sample size of 4, 8, 12, 16 or 20 vehicles or engines
for testing.
(ii) Calculate the Compliance Level as described in paragraph
(c)(1)(ii) of this section but use the value of k from paragraph (c)(4)
of this section for sequential reduced sampling.
(iii) You may increase the sample size by one or more sets of four
vehicles or engines, up to the maximum of 20, to recalculate the
Compliance Level.
(3) The Compliance Level for the cumulative sample of tested
vehicles or engines always replaces previously calculated values.
(4) Calculate the Compliance level for alternative sampling plans
in this paragraph (c) based on the values of k from the following
table:
Table 1 of Sec. 1071.40(c)(4) Values of k for Alternative Sampling Plans
----------------------------------------------------------------------------------------------------------------
Sequential reduced
Sample size Fixed reduced sampling sampling under
under paragraph (c)(1) paragraph (c)(2)
----------------------------------------------------------------------------------------------------------------
3............................................................. 1.602 .......................
4............................................................. 1.114 1.671
5............................................................. 0.895 .......................
6............................................................. 0.764 .......................
7............................................................. 0.674 .......................
8............................................................. 0.608 0.912
9............................................................. 0.555 .......................
10............................................................ 0.513 .......................
11............................................................ 0.478 .......................
12............................................................ 0.448 0.672
13............................................................ 0.422 .......................
14............................................................ 0.399 .......................
15............................................................ 0.379 .......................
16............................................................ 0.360 0.540
17............................................................ 0.343 .......................
18............................................................ 0.328 .......................
19............................................................ 0.314 .......................
20............................................................ 0.301 0.451
21............................................................ 0.289 .......................
22............................................................ 0.277 .......................
23............................................................ 0.266 .......................
----------------------------------------------------------------------------------------------------------------
Sec. 1071.45 Fail thresholds.
(a) A vehicle or engine you test under this subpart fails if its
final deteriorated test result exceeds the final value of the
Compliance Level under this subpart. For any other regulated pollutant,
a vehicle or engine fails if its final deteriorated test result exceeds
the applicable standard.
(b) An NCP family fails if the Compliance Level exceeds the Upper
Limit.
(c) Section 1071.105 describes the consequences of failing under
this section.
Sec. 1071.50 Test reporting.
(a) Within 30 days after completing the audit, send us a report
with the following information:
(1) Describe any facility used for testing under this subpart and
state its location.
(2) Identify the standards that apply for tested vehicles or
engines.
(3) Identify the deterioration factors you used to certify the NCP
family.
(4) Describe each tested vehicle or engine, including the NCP
family name, model year, build date, vehicle or engine configuration,
model number, identification number, and number of hours of operation
before testing.
(5) Identify where you accumulated hours of operation on the
vehicles or engines and describe the procedure and schedule you used.
(6) Provide the test number and identify the test procedure and the
date, time, and duration of testing. Also provide initial test results,
final test results, and final deteriorated test results as described in
Sec. 1071.40(a) for all tests. Provide emission figures for all
measured pollutants. Include information for both valid and invalid
[[Page 43292]]
tests and the reason for any invalidation.
(7) Identify the Compliance Level, consistent with Sec. 1071.40.
(8) Describe completely and justify any nonroutine adjustment,
modification, repair, preparation, maintenance, or test for the test
vehicle if you did not report it separately under this subpart. Include
the results of any emission measurements, regardless of the procedure
or type of equipment.
(b) We may ask you to add information to your written report, so we
can determine whether your new vehicles or engines conform to the
requirements of this part.
(c) An authorized representative of your company must sign the
following statement: ``We submit this report under Clean Air Act
section 206. Our testing conformed completely with the requirements of
40 CFR part 1071. All the information in this report is true and
accurate to the best of my knowledge. I know of the penalties for
violating the Clean Air Act and the regulations.'' (Authorized Company
Representative)
(d) Send reports to the Designated Compliance Officer using an
approved information format. If you want to use a different format,
send us a written request with justification for a waiver.
(e) We may post test results on publicly accessible databases and
we will send copies of your reports to anyone from the public who asks
for them, consistent with 40 CFR 1068.11.
Sec. 1071.55 Recordkeeping.
(a) We may review your records at any time so it is important to
keep required information readily available. Organize and maintain your
records as described in this section.
(b) Keep records for testing under this subpart for six years after
you complete all the testing required for the Production Compliance
Audit. You may use any format and on any media, as long as you can
promptly send us organized, written records in English if we ask for
them.
(c) Keep a copy of reports you submit to us.
(d) Keep the following additional records:
(1) A description of all equipment identified in 40 CFR part 1065,
subparts B and C, and 40 CFR part 1066, subpart B, that you used to
test vehicles or engines under this part.
(2) A complete record of each test, including the information
identified in 40 CFR part 1065.695 or 1066.695.
(3) The names of supervisors involved in each test.
(4) The name of anyone who authorizes adjusting, repairing,
preparing, or modifying a test vehicle or engine and the names of all
supervisors who oversee this work.
(5) If you shipped the vehicle or engine for testing, the date you
shipped it, the assembly plant or associated storage or port facility,
and the date the vehicle or engine arrived at the testing facility.
(6) Any records related to your audit that are not in the written
report.
(7) A brief description of any significant events during testing
not otherwise described in submitted reports or in this section, such
as engine damage during shipment.
(e) We may ask you to keep or send other information necessary to
implement this subpart.
Sec. 1071.60 EPA testing.
We may perform testing as described in this subpart by measuring
emissions from any of your production vehicles or engines. If you
certify engines using powertrain testing as specified in 40 CFR
1036.501(h), this section also applies for the powertrain test results.
(a) We may decide to do the testing at your plant or any other
facility. If we do this, you must deliver the engine to a test facility
we designate. The engine you provide must include appropriate
manifolds, aftertreatment devices, ECMs, and other emission-related
components not normally attached directly to the engine block. If we do
the testing at your plant, you must schedule it as soon as possible and
make available the instruments, personnel, and equipment we need.
(b) If we measure emissions on your engine, the results of that
testing become the official emission results for the engine as
specified in this paragraph (c). We will generally consider your data
in determining if your NCP family meets applicable requirements in this
part only if we later invalidate our data.
(c) Before we test one of your engines, we may set its adjustable
parameters to any point within the practically adjustable ranges.
(d) Before we test one of your engines, we may calibrate it within
normal production tolerances for anything we do not consider an
adjustable parameter. For example, we may calibrate it within normal
production tolerances for an engine parameter that is subject to
production variability because it is adjustable during production but
is not considered an adjustable parameter because it is permanently
sealed. For parameters that relate to a level of performance that is
itself subject to a specified range (such as maximum power output), we
will generally perform any calibration under this paragraph (d) in a
way that keeps performance within the specified range.
Sec. 1071.65 Labeling.
(a) Vehicles or engines you certify with a nonconformance penalty
must have an emission control information label as described in the
standard-setting part, with the following exceptions and
clarifications:
(1) Within 10 days after you establish the Compliance Level, you
must include the following statement on the emission control label or
on a supplemental label:
The manufacturer of this [vehicle or engine, as applicable] pays a
nonconformance penalty allowing it to be introduced into U.S. commerce
at an emission level higher than the applicable emission standard. The
Compliance Level is [identify the applicable Compliance Level and
pollutant].
(2) Amend the compliance statement to say that the vehicle or
engine complies with current standards using nonconformance penalties.
For example, include the following compliance statement for heavy-duty
engines certified under 40 CFR part 86 or part 1036: THIS ENGINE USES
NONCONFORMANCE PENALTIES TO COMPLY WITH U.S. EPA REGULATIONS FOR [MODEL
YEAR] HEAVY-DUTY HIGHWAY ENGINES.''
(3) If you produce vehicles or engines subject to a nonconformance
penalty and you introduce them into U.S. commerce without the label
statement described in paragraph (a)(1) of this section, you or your
agent must apply a supplemental label to all affected vehicles or
engines with the statement in paragraph (a)(1) of this section within
30 days after completing the Production Compliance Audit.
(4) Apply supplemental labels close to the emission control
information label, consistent with good engineering judgment.
(b) You may ask us to approve modified labeling requirements in
this section if you show that it is necessary or appropriate. We will
approve your request if your alternative label is consistent with the
intent of the labeling requirements of this section.
Subpart C--Penalty Provisions
Sec. 1071.80 Penalty parameters for specific standards.
(a) Implementing penalty provisions for a given standard depends on
establishing values for the following parameters, most of which are
illustrated in Figure 1 of Sec. 1071.85:
(1) S is the published standard that is the basis for calculating
nonconformance penalties.
[[Page 43293]]
(2) UL is the Upper Limit, which is the highest allowable emission
level for certifying vehicles or engines with nonconformance penalties.
See Sec. 1071.10.
(3) COC50 is an estimate for the 50th percentile cost of
compliance. This represents the average compliance cost to meet the
published standard by modifying a vehicle or engine starting with
emissions at the Upper Limit.
(4) COC90 is an estimate for the 90th percentile cost of
compliance. This represents the incremental compliance cost to meet the
published standard by modifying a vehicle or engine starting with
emissions at the Upper Limit.
(5) MC is an estimate of the marginal cost of compliance, expressed
in dollars per delta g/mile for vehicle standards and in dollars per
delta g/hp[middot]hr for engine standards. Penalty calculations in
Sec. 1071.85 use the following values for marginal cost of compliance:
(i) MC50 is an estimate of the 50th percentile marginal
cost of compliance.
(ii) MC90 is a calculated value representing the 90th
percentile marginal cost of compliance. MC90 is the slope of
the line on the penalty curve in Figure 1 of Sec. 1071.85 as the
Compliance Level increases from S. The value of F is the ratio of
MC90 to MC50, which is generally between 1.1 and
1.3.
(6) x is the emission level corresponding to COC50. The
equation for calculating nonconformance penalties depends on the slope
of the curve representing the marginal cost of compliance, so the
penalty calculation is different if the Compliance Level, CL, from
subpart B of this part is above or below x. We calculate x for a
specific emission standard from the following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.114
(7) FE&D is a fractional value representing the portion
of the estimated compliance costs attributed to engineering and
development. Section 1071.90 describes how there may be a refund for a
portion of the nonconformance penalty based on FE&D.
(b) We will determine appropriate values for the cost parameters in
paragraph (a) of this section. These estimates will generally be based
on the analysis used to adopt the relevant standard, including the date
associated with that analysis, though we may augment the data with
additional information if we adopt the penalty provisions in a later
rulemaking. We may adjust costs to account for inflation based on
changes to the Consumer Price Index between the date of the analysis
and January of the calendar year preceding the model year in which a
nonconformance penalty is first available.
(c) Values for calculating nonconformance penalties for historical
standards are in appendix A of this part.
(d) Nonconformance penalties are available for diesel-fueled Medium
HDE and diesel-fueled Heavy HDE subject to the 35 mg/hp[middot]hr
NOX standard in 40 CFR 1036.104, subject to the following
provisions:
(1) For engines subject to nonconformance penalties, you may
certify the NCP family under 40 CFR part 86 or part 1036, as follows:
(i) Engines certified under 40 CFR part 86 are subject to all
standards, testing and compliance requirements, and other regulatory
provisions as described for model year 2026 in 40 CFR part 86, subpart
A. Such engines are not subject to Production Compliance Audits and are
instead assigned a Compliance Level of 200 mg/hp-hr.
(ii) Engines certified under 40 CFR part 1036 are subject to all
standards, testing and compliance requirements, and other regulatory
provisions as described in 40 CFR part 1036 for the current model year,
except for the NOX standards. Such engines are subject to
Production Compliance Audits to establish a Compliance Level as
described in subpart B of this part.
(2) The following parameter values apply:
--------------------------------------------------------------------------------------------------------------------------------------------------------
S (mg/hp- UL (mg/hp- MC50 ($ per mg/
Engine class hr) hr) COC50 COC90 hp-hr) F FE&D
--------------------------------------------------------------------------------------------------------------------------------------------------------
Diesel-fueled Medium HDE................................ 35 200 $3,683 $4330 $72 1.176 0.032
Diesel-fueled Heavy HDE................................. 35 200 6,202 6781 82 1.1 0.025
--------------------------------------------------------------------------------------------------------------------------------------------------------
(3) Determine the Compliance Level for the NCP family based on
engine testing over the FTP duty cycle.
(4) The Compliance Level also serves as the emission standard for
in-use testing and other compliance testing for individual engines over
the FTP and SET duty cycles. Determine adjusted values for the
Compliance Level as described for Family Emission Limits in 40 CFR
1036.104(c)(3) for the Low Load Cycle, idle testing, and off-cycle
testing, as applicable. Note that these adjusted values for the
Compliance Level apply only for determining whether an individual
engine complies with emission standards; those adjusted values do not
apply for qualifying NCP families under this part or for calculating
penalty values under Sec. 1071.85.
(5) The cost values in paragraph (d)(2) of this section are
expressed in 2024 dollars. We will calculate the Annual Adjustment
Factor in Sec. 1071.85(c) using I0 = 0.03 to represent the
Consumer Price Index as of January 2026. Section 1071.85 describes how
to calculate penalty values to account for inflation.
Sec. 1071.85 Calculating the nonconformance penalty.
(a) This section describes how to calculate the nonconformance
penalty for a specific NCP family based on the following parameters:
(1) Section 1071.80 describes several parameters that are specific
to the published standard, mostly to characterize the estimated cost of
meeting the standard.
(2) CL is the Compliance Level for the NCP family, which is
generally based on testing as described in subpart B of this part. The
penalty provisions of this part apply only if the value of the
Compliance Level is above the standard and at or below the Upper Limit.
(3) AAF is an Annual Adjustment Factor. Paragraph (c) of this
section describes how the Annual Adjustment Factor serves to increase
the penalty over time to account for inflation and continued use of the
penalty provisions.
(b) Calculate a per-vehicle or per-engine nonconformance penalty
for an NCP family, rounded to the nearest dollar, using one of the
following equations:
(1) Use the following equation if the Compliance Level is at or
below x:
[[Page 43294]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.115
Where:
i is a counting variable to represent the current year based on the
number of years you have certified vehicles or engines from a class
with nonconformance penalties.
[Pi]ni=1 AAFi is the product of consecutive
Annual Adjustment Factors for n years. For example, in the third
year of certifying with nonconformance penalties,
[Pi]ni=3 AAFi AAF1 [middot]
AAF2 [middot] AAF3.
(2) Use the following equation if the Compliance Level is above x:
[GRAPHIC] [TIFF OMITTED] TP14JY26.116
(c) Calculate the Annual Adjustment Factor for year i using the
following equation:
[GRAPHIC] [TIFF OMITTED] TP14JY26.117
Where:
Ii-1 = The fractional value representing the increase in
overall consumer price index in year (i-1), as described in
paragraph (d) of this section.
Ai = Usage adjustment factor in year i: Let Ai
= 0.08, except that A1 = 0 and A2 = 0.10.
fraci-1 = Fraction of vehicles or engines in a class that
are certified using nonconformance penalties in the year before the
current year i, as described in paragraph (d) of this section. If
fraci-1 is above 0.50, then calculate AAFi
using fraci-1 = 0.50.
(d) We will calculate your Annual Adjustment Factor based on the
following information and procedures:
(1) Send us the following information by April 30 of each year that
nonconformance penalties are available:
(i) The number of vehicles or engines from each class that you
produced through March 31 in the current model year. Identify separate
numbers of vehicles or engines certified with and without a
nonconformance penalty. If your current model year involves production
of additional vehicles or engines after March 31, also send us
estimated values for those additional vehicles or engines.
(ii) If your report from the previous year included estimated
production numbers, send us actual production numbers to replace your
estimated values.
(2) We will determine the value of fraci-1 for
calculating the Annual Adjustment Factor starting with the second year
that nonconformance penalties are available based the information you
send us, combined with nationwide production values aggregated from all
manufacturers. We will estimate production volumes from manufacturers
not using nonconformance penalties based on production reports,
projected volumes from applications for certification, and any other
relevant information. As an example, shortly after April 30, 2027, we
will use actual and estimated production volumes for each class from
all manufacturers to determine frac2027, which is needed to
determine nonconformance penalties for model year 2028. In that
example, if we receive updated information for model year 2027 with
actual production volumes in April 2028, we will use that information
to create updated values of frac2027 and AAF2027
to determine nonconformance penalties for model year 2029. We will use
updated values accounting for actual production volumes to calculate
nonconformance penalties prospectively; we will not use those updated
values to revise nonconformance penalties from an earlier model year.
(3) We will determine the value of Ii-1 based on the
Consumer Price Index for All Urban Consumers published by the Bureau of
Labor Statistics at www.bls.gov/data/inflation_calculator.htm. We will
determine the value of I0 based on the change in prices between the
date associated with establishing cost parameters and January of the
calendar year preceding the model year in which a nonconformance
penalty is first available; see Sec. 1071.80. For later model years,
we will determine the value of In-1 based on the change in
prices each January.
(e) The following figure illustrates how the various parameters
support calculating nonconformance penalties:
[[Page 43295]]
[GRAPHIC] [TIFF OMITTED] TP14JY26.118
Sec. 1071.90 Making payments.
This section describes procedures for paying penalties under this
part.
(a) We will notify you in writing once we establish a specific
nonconformance penalty based on the Compliance Levels that apply for
affected vehicles or engines.
(b) The penalty applies for all nonconforming vehicles or engines
you produce from any assembly plant for the following production
periods:
(1) Penalties start to apply ten days after you conclude that an
NCP family has failed a Selective Enforcement Audit. In all other
cases, penalties apply starting with the beginning of the model year.
(2) Penalties continue to apply for the rest of the model year
unless or until you demonstrate under Sec. 1071.30(c) or (d) that
vehicles or engines meet emission standards. Penalties continue to
apply for any configurations not covered by the compliance
demonstration.
(3) Penalties may carry over to future model years indefinitely.
Section 1071.85 describes how the penalty increases for each model
year.
(c) A penalty assessment applies for each calendar quarter based on
the number of vehicles or engines you produce. Payment is due for each
quarter in the month following the end of the quarter, on April 30,
July 30, October 30, and January 30. We may approve your request for an
alternative payment schedule, but any delay from the default schedule
is subject to interest payments as described in paragraph (e) of this
section. For each quarterly due date, send us the following information
about vehicles and engines that are subject to nonconformance
penalties, even if total production was zero in the preceding quarter:
(1) Identify the NCP family for all affected vehicles or engines.
(2) Identify quarterly production totals. Identify production
totals separately by subfamily, if applicable.
(3) Show your calculations to determine the total payment penalty
for the preceding quarter, including any interest payments.
(4) An authorized representative of your company must sign the
following statement: ``We submit this report under Clean Air Act
section 206. All the information in this report is true and accurate to
the best of my knowledge. I know of the penalties for violating the
Clean Air Act and the regulations.'' (Authorized Company
Representative)
(d) We may ask you to demonstrate the accuracy of your quarterly
production numbers, or any other information in reports you submit
under paragraph (c) of this section.
(e) Calculate interest charges starting with the due date for any
missed or partial payments, including payments on an approved
alternative schedule and payments that are withheld during hearing
deliberations. Interest charges continue to apply for each quarter with
an outstanding balance due. Calculate the total interest payment based
on the outstanding balance for the number of quarters that any penalty
payment is overdue by applying the interest rate for the applicable
payment due date from www.fiscal.treasury.gov/reports-statements/cvfr/index.html.
(f) Send payments to www.pay.gov.
(g) Credits and refunds apply as follows:
(1) If you overpay your penalty for any reason, you may subtract
the overpayment from future payments. We may alternatively approve your
request for a refund.
(2) You can claim a refund for a portion of the nonconformance
penalty associated with your engineering and development costs to meet
the new standards if you demonstrate that modified vehicles or engines
to be fully compliant, including an updated Compliance Level under
Sec. 1071.30(c) or (d) that meets the applicable standard. Calculate
the refund of payments you made to us, REPA, as follows:
[GRAPHIC] [TIFF OMITTED] TP14JY26.119
Where:
Dn = discount factor corresponding to the number of model
years, n, nonconformance penalties have been available for a given
class of vehicles or engines before completing certification that
fully complies with applicable standards, where n=1 for the first
year nonconformance penalties were available. Use the following
values for Dn:
D1 = 0.90.
D2 = 0.79.
D3 = 0.67.
[[Page 43296]]
D4 = 0.54.
D5 = 0.39.
D6 = 0.23.
D7 = 0.05.
Dn = 0.00 for n = 8 or more.
FE&D = a fractional value representing the manufacturer's
engineering and development costs relative to the total compliance
costs as specified in Sec. 1071.80.
NCP1 = the nonconformance penalty identified in paragraph
(a) of this section for the first model year.
ProdCal = number of vehicles or engines from the same
class you demonstrate have been titled, registered, or principally
used in California and for which you paid nonconformance penalties
to the State of California.
Prodtot = total number of vehicles or engines from the
same class for which you paid nonconformance penalties to EPA or the
State of California.
(3) We will not pay interest on any money we owe you.
Subpart D--Administrative Provisions
Sec. 1071.100 Entry and access.
Provisions related to EPA inspections apply as specified in 40 CFR
1068.20.
Sec. 1071.105 Suspending and voiding certificates of conformity.
(a) The certificate of conformity is automatically suspended for a
vehicle or engine if it fails as described in Sec. 1071.45(a). Notify
us within five days after you make this determination. You must take
the following actions before your certificate of conformity can cover
that vehicle or engine:
(1) Correct the problem and retest the vehicle or engine to show it
complies with all emission standards.
(2) Send us a written report describing your test results and the
remedy for each vehicle or engine before introducing the vehicle or
engine into U.S. commerce. You may include this information in the
report you submit under Sec. 1071.50.
(b) We may suspend the certificate of conformity if you do not meet
the requirements and deadlines in this part.
(c) We may suspend the certificate of conformity if the Compliance
Level as determined in Sec. 1071.45(b) is above the Upper Limit. We
may void the certificate of conformity if you fail to recall any
vehicles or engines whose Compliance Level is found to be above the
Upper Limit.
(d) We may void your certificate of conformity if you fail to fully
pay the nonconformance penalty.
(e) Except as described in paragraph (a) of this section, we will
tell you in writing if we suspend, revoke, or void your certificate of
conformity in whole or in part. The suspension is effective when you
receive our notice.
(f) You may request that we reinstate a suspended, revoked, or
voided certificate of conformity by sending us a written report that
identifies the reason for the failure and demonstrates that you comply
with the requirements of this part. Include in the proposed remedy any
quality control measures you propose to keep the problem from happening
again. If the failure is related to measured emission levels, give us
test data from production vehicles or engines showing that vehicles or
engines in the remedied family comply with all the emission standards
that apply. We may include any reasonable conditions when reinstating a
certificate.
Sec. 1071.110 Hearing procedures.
(a) The provisions of 40 CFR part 1068, subpart G, apply if you
request a hearing regarding nonconformance penalties or suspending,
revoking, or voiding a certificate of conformity under this subpart.
(b) If we establish penalties under Sec. 1071.90(a) and we agree
to your request for a hearing related to the nonconformance penalty
under 40 CFR 1068.625, you may produce affected vehicles or engines
before the hearing deliberations conclude. However, if the hearing
results in a final decision requiring a penalty, the payment is due,
with interest, ten days after the Presiding Officer's final decision.
Sec. 1071.115 Confidential information.
The provisions of 40 CFR 1068.10 and 1068.11 apply for information
you submit under this part.
Sec. 1071.120 List of acronyms.
The following acronyms and abbreviations apply to this part:
------------------------------------------------------------------------
gross vehicle weight rating, as
GVWR defined in 40 CFR 1036.801.
------------------------------------------------------------------------
HDE.................................... heavy-duty engine, as defined
in 40 CFR 1036.801.
HDGE................................... heavy-duty gasoline engine.
HDDE................................... heavy-duty diesel engine.
LDT3................................... Light-duty truck 3, as defined
in 40 CFR 86.1803-01.
NCP.................................... nonconformance penalty.
------------------------------------------------------------------------
Appendix A to Part 1071--Penalty Parameter Values for Historical
Standards
This appendix describes the values for the parameters identified
in Sec. 1071.80 to support penalty calculations for historical
standards.
(a) The following parameter values applied for vehicle-based
standards:
Table 1 to Paragraph (a) of Appendix A to Part 1071--Penalty Parameters for Vehicle-Based Standards
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MC50 ($ per g/
Model year for new standard Vehicle class Pollutant S (g/mi) COC50 COC90 mi) F FE&D Dollar basis
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1987.................................. Diesel vehicles <=14,000 PM....................... 0.26 $368 $541 $3,200 1.2 0.11 Dec. 1984.
lb GVWR.
1991.................................. Diesel vehicles <=14,000 PM....................... 0.13 711 1,396 2,960 1.2 0.01 Dec. 1989.
lb GVWR.
1996.................................. Diesel LDT3.............. PM....................... 0.10 441 1,471 14,700 1.2 0.093 Dec. 1994.
1996.................................. Diesel LDT3.............. NOX...................... 0.98 654 779 908 1.2 0.082 Dec. 1994.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(b) The following parameter values applied for engine-based
standards:
Table 1 to Paragraph (b) of Appendix A to Part 1071--Penalty Parameters for Engine-Based Standards
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MC50 ($ per g/
Model year for new standard Engine class Pollutant S (g/hp-hr) COC50 COC90 hp-hr) F FE&D Dollar basis
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1987.................................. HDGE for vehicles HC....................... 1.1 $45 $95 $83 1.2 0.06 Dec. 1984.
<=14,000 lb GVWR.
1987.................................. HDGE for vehicles CO....................... 14.4 45 95 4 1.2 0.06 Dec. 1984.
<=14,000 lb GVWR.
1988.................................. Light HDDE............... PM....................... 0.60 71 83 340 1.2 0.64 Dec. 1984.
[[Page 43297]]
1988.................................. Medium HDDE.............. PM....................... 0.60 84 97 382 1.2 0.62 Dec. 1984.
1988.................................. Heavy HDDE............... PM....................... 0.60 87 101 725 1.2 0.60 Dec. 1984.
1990.................................. Light HDDE............... NOX...................... 6.0 18 41 49 1.2 0.36 Dec. 1984.
1990.................................. Medium HDDE.............. NOX...................... 6.0 1,125 1,540 883 1.2 0.02 Dec. 1984.
1990.................................. Heavy HDDE............... NOX...................... 6.0 1,278 1,980 1,733 1.2 0.02 Dec. 1984.
1991.................................. Light HDDE............... NOX...................... 5.0 830 946 1,167 1.2 0.12 Dec. 1989.
1991.................................. Medium HDDE.............. NOX...................... 5.0 905 1,453 1,417 1.2 0.11 Dec. 1989.
1991.................................. Heavy HDDE............... NOX...................... 5.0 930 1,590 2,250 1.2 0.11 Dec. 1989.
1993.................................. Urban bus HDE............ PM....................... 0.10 4,020 4,535 22,971 1.2 0.02 Dec. 1989.
1994.................................. Urban bus HDE............ PM....................... 0.07 3,292 10,014 109,733 1.2 0.38 Dec. 1991.
1994.................................. Light HDDE............... PM....................... 0.10 772 1,325 8,178 1.2 0.081 Dec. 1991.
1994.................................. Medium HDDE.............. PM....................... 0.10 1,276 3,298 15,370 1.2 0.098 Dec. 1991.
1994.................................. Heavy HDDE............... PM....................... 0.10 2,105 6,978 30,070 1.2 0.083 Dec. 1991.
1996.................................. Urban bus HDE............ PM....................... 0.05 576 6,569 28,800 1.2 0.500 Dec. 1994.
1998.................................. Light HDDE............... NOX...................... 4.0 833 1,513 833 1.2 0.039 Dec. 1994.
1998.................................. Medium HDDE.............. NOX...................... 4.0 444 1,368 444 1.2 0.043 Dec. 1994.
1998.................................. Heavy HDDE............... NOX...................... 4.0 1,086 2,540 1,086 1.2 0.039 Dec. 1994.
2004.................................. Light HDDE............... NOX+NMHC................. 2.4 1,240 2,710 2,000 1.3 0.403 Dec. 2001.
2004.................................. Medium HDDE.............. NOX+NMHC................. 2.4 2,740 4,930 1,400 1.3 0.197 Dec. 2001.
2004.................................. Heavy HDDE............... NOX+NMHC................. 2.4 6,810 12,210 5,600 1.3 0.090 Dec. 2001.
2004.................................. Urban bus HDE............ NOX+NMHC................. 2.4 3,930 6,660 3,800 1.3 0.155 Dec. 2001.
2012.................................. Heavy HDDE............... NOX...................... 0.20 3,219 3,775 10,729 1.173 0.005 Dec. 2011.
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[FR Doc. 2026-14112 Filed 7-13-26; 8:45 am]
BILLING CODE 6560-50-P