[Congressional Bills 119th Congress]
[From the U.S. Government Publishing Office]
[H.R. 9618 Introduced in House (IH)]
<DOC>
119th CONGRESS
2d Session
H. R. 9618
To amend the Clean Air Act to preserve regulatory stability for motor
vehicles, motor vehicle engines, nonroad vehicles, and nonroad engines,
and for other purposes.
_______________________________________________________________________
IN THE HOUSE OF REPRESENTATIVES
July 9, 2026
Mrs. Fedorchak (for herself, Mr. Davis of North Carolina, Mr. Finstad,
Mr. Bergman, and Mrs. Fischbach) introduced the following bill; which
was referred to the Committee on Energy and Commerce
_______________________________________________________________________
A BILL
To amend the Clean Air Act to preserve regulatory stability for motor
vehicles, motor vehicle engines, nonroad vehicles, and nonroad engines,
and for other purposes.
Be it enacted by the Senate and House of Representatives of the
United States of America in Congress assembled,
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Diesel Engine Flexibility Act'' or
the ``DEF Act''.
SEC. 2. PRESERVATION OF ON-ROAD VEHICLE AND ENGINE REGULATORY
STABILITY.
Section 202 of the Clean Air Act (42 U.S.C. 7521) is amended by
adding at the end the following:
``(n) Preservation of Motor Vehicle and Engine Regulatory
Stability.--
``(1) Guidance-based safe harbor.--During the period of 10
years beginning on the date of enactment of this subsection,
implementation of an inducement strategy or diesel exhaust
fluid quality monitoring described in the covered guidance
documents with respect to new and in-use motor vehicles and
engines, including heavy-duty engines, heavy-duty vehicles,
light-duty vehicles, light-duty trucks, and light-duty engines,
shall not constitute a prohibited act under this title if the
implementation is undertaken in a manner consistent with the
covered guidance documents, to the extent such covered guidance
documents apply to such a motor vehicle or engine that is
required to comply with the 2007 standards or the 2010
standards, provided that such implementation is consistent with
otherwise applicable certification requirements and useful life
requirements under this title.
``(2) Regulatory stability.--
``(A) Temporary regulatory stability.--During the
period of 10 years described in paragraph (1), the
Administrator may not promulgate, revise, authorize, or
implement under this section or section 209(b) any
regulation containing any standard or other requirement
applicable to new or in-use motor vehicles or engines,
including heavy-duty engines, heavy-duty vehicles,
light-duty vehicles, light-duty trucks, and light-duty
engines, that is more stringent than the 2007 standards
and the 2010 standards, except that nothing in this
paragraph shall prohibit the Administrator from--
``(i) approving software updates, repair
strategies, diagnostic improvements, or
monitoring approaches consistent with the
covered guidance documents;
``(ii) enforcing prohibitions against
defeat devices, defeat strategies,
circumvention, fraud, tampering, or operations
outside the conditions applicable to certified
configurations under this title;
``(iii) implementing any recall, defect
reporting, certification, warranty, or other
administrative requirements that do not impose
more stringent emission standards or materially
increase compliance obligations applicable to
such motor vehicles or engines that are
required to comply with the 2007 standards or
the 2010 standards; or
``(iv) approving a voluntary manufacturer
action that maintains compliance with otherwise
applicable certification requirements and
useful life requirements promulgated under this
title.
``(B) Lead time.--After the expiration of the
period described in paragraph (1), any standard or
other requirement promulgated, revised, or authorized
under this section or section 209(b) applicable to new
or in-use motor vehicles or engines, including heavy-
duty engines, heavy-duty vehicles, light-duty vehicles,
light-duty trucks, and light-duty engines, that revises
or succeeds the 2007 standards or the 2010 standards
shall--
``(i) apply for a period of no less than 3
model years; and
``(ii) take effect no earlier than the
model year commencing 5 years after such new or
revised standard or other requirement is
promulgated, revised, or authorized.
``(C) Required considerations.--After the
expiration of the period described in paragraph (1), in
promulgating, revising, or authorizing a standard or
other requirement under this section or section 209(b)
applicable to new or in-use motor vehicles or engines,
including heavy-duty engines, heavy-duty vehicles,
light-duty vehicles, light-duty trucks, and light-duty
engines, that revises or succeeds the 2007 standards or
the 2010 standards, the Administrator shall consider--
``(i) the need to reduce unnecessary
operational disruption, derates, shutdowns, and
related operating restrictions for owners and
operators of such motor vehicles and engines;
``(ii) the need to preserve operating
conditions and engine configurations certified
to comply with the 2007 standards or the 2010
standards that protect the durability of such
motor vehicles and engines, selective catalytic
reduction systems, diesel particulate filter
systems, and related aftertreatment components;
``(iii) the effects of the proposed
standard or other requirement on resale value,
financing expectations, dealer inventories, and
equipment availability across such motor
vehicles and engines that are already in
service or are available for sale;
``(iv) the costs of the proposed standard
or other requirement to owners and operators of
such motor vehicles and engines, including
downtime, repair, service, logistics, and
equipment replacement costs;
``(v) the need for nationally consistent
requirements for such motor vehicles and
engines; and
``(vi) the effects of the proposed standard
or other requirement on harmonization across
such motor vehicle and engine categories and
engine families, equipment models, and shared
engine or aftertreatment designs used across
on-road categories.
``(3) Rule of construction.--Nothing in this subsection
shall be construed to--
``(A) authorize permanent disablement of an
emissions control system;
``(B) exempt any new or in-use motor vehicle or
engine, including a heavy-duty engine, a heavy-duty
vehicle, a light-duty vehicle, a light-duty truck, and
a light-duty engine, from otherwise applicable emission
standards promulgated under this title; or
``(C) prohibit the Administrator from approving
software updates, repair strategies, diagnostic
improvements, or monitoring approaches implemented
consistent with otherwise applicable certification
requirements and useful life requirements under this
title.
``(4) Definitions.--In this subsection:
``(A) 2007 standards.--The term `2007 standards'
means the standards and associated certification and
compliance requirements under section 86.007-11 of
title 40, Code of Federal Regulations, as in effect on
January 1, 2025.
``(B) 2010 standards.--The term `2010 standards'
means the standards and associated certification and
compliance requirements under section 86.010-18 of
title 40, Code of Federal Regulations, as in effect on
January 1, 2025.
``(C) Covered guidance documents.--The term
`covered guidance documents' means--
``(i) the guidance entitled `Revised
Guidance for Light Duty Vehicles, Heavy-Duty
Diesel Engines and Nonroad Compression-Ignition
(CI) Engines Using Selective Catalytic
Reduction (SCR) Technologies', issued on August
11, 2025, and designated as IACD-2025-10; and
``(ii) the guidance entitled `DEF Quality
Monitoring Using Alternate Sensor
Technologies', issued on March 26, 2026, and
designated as IACD-2026-05.''.
SEC. 3. PRESERVATION OF NONROAD VEHICLES AND NONROAD ENGINES REGULATORY
STABILITY.
Section 213 of the Clean Air Act (42 U.S.C. 7547) is amended by
adding at the end the following:
``(e) Nonroad Vehicle and Nonroad Engine Regulatory Stability.--
``(1) Guidance-based safe harbor.--During the period of 10
years beginning on the date of enactment of this subsection,
implementation of an inducement strategy, repair-related
override, or diesel exhaust fluid quality monitoring described
in the covered guidance documents with respect to a nonroad
vehicle or nonroad engine, including a nonroad compression-
ignition engine and equipment that uses such an engine, shall
not constitute a prohibited act under this title if the
implementation is undertaken in a manner consistent with the
covered guidance documents, to the extent such covered guidance
documents apply to such a nonroad vehicle or nonroad engine
that is required to comply with the Tier 4 standards, provided
that such implementation is consistent with otherwise
applicable certification requirements and useful life
requirements under this title.
``(2) Regulatory stability.--
``(A) Temporary regulatory stability.--During the
period of 10 years described in paragraph (1), the
Administrator may not promulgate, revise, authorize, or
implement under this section or section 209(e)(2) any
regulation containing any standard or other requirement
applicable to nonroad vehicles or nonroad engines,
including nonroad compression-ignition engines and
equipment containing such engines, that is more
stringent than the Tier 4 standards, except that
nothing in this paragraph shall prohibit the
Administrator from--
``(i) approving software updates, repair
strategies, diagnostic improvements, or
monitoring approaches consistent with the
covered guidance documents;
``(ii) enforcing prohibitions against
defeat devices, defeat strategies,
circumvention, fraud, tampering, or operations
outside the conditions applicable to certified
configurations under this title;
``(iii) implementing any recall, defect
reporting, certification, warranty, or other
administrative requirements that do not impose
more stringent emission standards or materially
increase compliance obligations applicable to
such nonroad vehicles or nonroad engines that
are required to comply with the Tier 4
standards; or
``(iv) approving a voluntary manufacturer
action that maintains compliance with otherwise
applicable certification requirements and
useful life requirements promulgated under this
title.
``(B) Lead time.--After the expiration of the
period described in paragraph (1), any standard or
other requirement promulgated, revised, or authorized
under this section or section 209(e)(2) applicable to
nonroad vehicles or nonroad engines, including nonroad
compression-ignition engines and equipment containing
such engines, that revises or succeeds the Tier 4
standards shall--
``(i) apply for a period of no less than 3
model years; and
``(ii) take effect no earlier than the
model year commencing 5 years after such new or
revised standard or other requirement is
promulgated, revised, or authorized.
``(C) Required considerations.--After the
expiration of the period described in paragraph (1), in
promulgating, revising, or authorizing a standard or
other requirement under this section or section
209(e)(2) applicable to nonroad vehicles or nonroad
engines, including nonroad compression-ignition engines
and equipment containing such engines, that revises or
succeeds the Tier 4 standards, the Administrator shall
consider--
``(i) the need to reduce unnecessary
operational disruption, derates, shutdowns, and
related operating restrictions for owners and
operators of such nonroad vehicles or nonroad
engines;
``(ii) the need to preserve operating
conditions and engine configurations certified
to comply with the Tier 4 standards that
protect the durability of such nonroad vehicles
and nonroad engines, selective catalytic
reduction systems, diesel particulate filter
systems, and related aftertreatment components;
``(iii) the effects of the proposed
standard or other requirement on resale value,
financing expectations, dealer inventories, and
equipment availability across such nonroad
vehicles or nonroad engines that are already in
service or are available for sale;
``(iv) the costs of the proposed standard
or other requirement to owners and operators of
such nonroad vehicles or nonroad engines,
including downtime, repair, service, logistics,
and equipment replacement costs;
``(v) the need for nationally consistent
requirements for such nonroad vehicles and
nonroad engines; and
``(vi) the effects of the proposed standard
or other requirement on harmonization across
such nonroad vehicle and nonroad engine
categories and engine families, equipment
models, and shared engine or aftertreatment
designs used across nonroad categories.
``(3) Rule of construction.--Nothing in this subsection
shall be construed to--
``(A) authorize permanent disablement of an
emissions control system;
``(B) exempt any nonroad vehicle or nonroad engine,
including a nonroad compression-ignition engine and
equipment containing such an engine, from otherwise
applicable emission standards promulgated under this
title; or
``(C) prohibit the Administrator from approving
software updates, repair strategies, diagnostic
improvements, or monitoring approaches implemented
consistent with otherwise applicable certification
requirements and useful life requirements under this
title.
``(4) Definitions.--In this subsection:
``(A) Covered guidance documents.--The term
`covered guidance documents' means--
``(i) the guidance entitled `Revised
Guidance for Light Duty Vehicles, Heavy-Duty
Diesel Engines and Nonroad Compression-Ignition
(CI) Engines Using Selective Catalytic
Reduction (SCR) Technologies', issued on August
11, 2025, and designated as IACD-2025-10;
``(ii) the guidance entitled `Clarification
Regarding the Practice of Temporarily Disabling
Aspects of an Emission Control System or
Components to Repair or Maintain a Nonroad
Engine', issued January 30, 2026, and
designated IACD-2026-01; and
``(iii) the guidance entitled `DEF Quality
Monitoring Using Alternate Sensor
Technologies', issued on March 26, 2026, and
designated as IACD-2026-05.
``(B) Tier 4 standards.--The term `Tier 4
standards' means the standards and associated
certification and compliance requirements under parts
1039 and 1068 of title 40, Code of Federal Regulations,
as in effect on January 1, 2025.''.
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