S 3135

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IN THE SENATE OF THE UNITED STATES

November 6, 2025

Mr. Sullivan (for himself, Ms. Lummis, Mr. Curtis, and Ms. Murkowski) introduced the following bill; which was read twice and referred to the Committee on Environment and Public Works

September 16, 2026

Reported by Mrs. Capito, with an amendment [Strike out all after the enacting clause and insert the part printed in italic]

A BILL

To require the Administrator of the Environmental Protection Agency to authorize manufacturers of certain vehicles to suspend engine derate or shutdown functions in prolonged cold weather conditions, 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 “Cold Weather Diesel Reliability Act of 2025”.

SEC. 2. FINDINGS.

Congress finds that— (1) diesel vehicles are vital for critical transportation and emergency services in cold weather regions; (2) in rural regions with prolonged freezing conditions, diesel exhaust fluid storage, supply, and system functionality are frequently unreliable and logistically impractical on a year-round basis; (3) automatic engine shutdowns and power reductions due to emissions control malfunctions in extreme cold pose serious, life-threatening risks; and (4) emissions safeguards under the Clean Air Act (42 U.S.C. 7401 et seq.) were never intended to jeopardize human safety or impede critical mobility.

SEC. 3. DEFINITIONS.

In this Act: (1) Administrator.—The term “Administrator” means the Administrator of the Environmental Protection Agency. (2) Covered manufacturer.—The term “covered manufacturer” means the manufacturer (as defined in section 216 of the Clean Air Act (42 U.S.C. 7550)) of a covered vehicle or an engine of a covered vehicle. (3) Covered vehicle.—The term “covered vehicle” means an on-highway diesel vehicle or nonroad diesel equipment.

SEC. 4. DIESEL ENGINE EMISSIONS RELIEF IN COLD WEATHER REGIONS.

(a) Cold Weather Sensor Mitigation Measures.—Not later than 180 days after the date of enactment of this Act, the Administrator shall revise any applicable regulation under the Clean Air Act (42 U.S.C. 7401 et seq.) that applies to covered vehicles or engines used in covered vehicles to authorize covered manufacturers to suspend inducement-related engine derate or shutdown functions that are triggered by emissions control system faults when ambient temperatures are at or below zero degrees Centigrade and to specify that no party other than a covered manufacturer shall suspend those inducement- related derate or shutdown functions, subject to the conditions that— (1) the engine returns to normal emission control operation, including inducement enforcement, once ambient temperatures rise above zero degrees Centigrade; and (2) continued maximum engine performance when ambient temperatures are at or below zero degrees Centigrade is necessary to prevent occupational danger, equipment failure, or loss of essential transportation functionality in remote areas with limited roadside support or emergency communications access. (b) Relief to Regions With Prolonged Freezing Conditions.— (1) In general.—Not later than 180 days after the date of enactment of this Act, the Administrator shall revise any applicable regulation under the Clean Air Act (42 U.S.C. 7401 et seq.) to grant a year-round exemption from diesel exhaust fluid system requirements any covered vehicle that— (A) is primarily operated north of 59 degrees north latitude, as demonstrated by documentation of commercial operation, domicile location, or maintenance and dispatch records; or (B) encounters operational or logistical conditions characterized by prolonged ambient temperatures that— (i) are below the freezing point of diesel exhaust fluid; or (ii) otherwise make the use of the diesel exhaust fluid system impractical. (2) Scope of relief.—In carrying out paragraph

(1), the Administrator shall grant to a covered vehicle described in subparagraph (A) or (B) of that paragraph an exemption from any requirement to include an engine derate or shutdown function that is triggered by the absence, degradation, malfunction, or fault of a diesel exhaust fluid system, including any associated sensors or electronic control modules.

SEC. 5. RULE OF CONSTRUCTION.

Nothing in this Act waives compliance with any emissions standard under the Clean Air Act (42 U.S.C. 7401 et seq.) outside of— (1) the temporary cold-weather operational mode authorized under section 4(a); and (2) the exemption from diesel exhaust fluid system requirements under section 4(b).

SECTION 1. SHORT TITLE.

This Act may be cited as the “Cold Weather Diesel Reliability Act of 2026”.

SEC. 2. DEFINITIONS.

In this Act:

(1) Administrator.—The term “Administrator” means the Administrator of the Environmental Protection Agency.

(2) Agricultural equipment.—

(A) In general.—The term “agricultural equipment” means—

(i) nonroad diesel equipment and machinery, including tractors, combines, tillage implements, balers, planters, seeding equipment, and any other self-propelled equipment that is primarily designed for use in spraying, fertilizing, or harvesting covered commodities (as defined in section 1111 of the Agricultural Act of 2014 (7 U.S.C. 9011)); and

(ii) a nonroad diesel engine that powers equipment and machinery described in clause

(i).

(B) Exclusion.—The term “agricultural equipment” does not include a self-propelled machine designed primarily for the transportation of persons or property on a street or highway.

(3) Covered manufacturer.—The term “covered manufacturer” means the manufacturer (as defined in section 216 of the Clean Air Act (42 U.S.C. 7550)) of a covered vehicle or an engine of a covered vehicle.

(4) Covered vehicle.—The term “covered vehicle” means an on-highway diesel vehicle or nonroad diesel equipment.

SEC. 3. DIESEL ENGINE DERATE RELIEF.

(a) Cold Weather Sensor Mitigation Measures.—Not later than 180 days after the date of enactment of this Act, the Administrator shall revise any applicable regulation under the Clean Air Act (42 U.S.C. 7401 et seq.) that applies to covered vehicles or engines used in covered vehicles to authorize covered manufacturers of those covered vehicles or engines to suspend inducement-related engine derate or shutdown functions that are triggered by the emissions control system when ambient temperatures are at or below 20 degrees Fahrenheit and to specify that no party other than a covered manufacturer shall suspend those inducement-related derate or shutdown functions, subject to the condition that the engine shall return to normal operation once ambient temperatures rise above 20 degrees Fahrenheit.

(b) Relief to Farmers and Arctic Regions.—Notwithstanding any other provision of law, not later than 180 days after the date of enactment of this Act, the Administrator shall revise any applicable regulation under the Clean Air Act (42 U.S.C. 7401 et seq.) to authorize covered manufacturers to permanently suspend inducement- related engine derate or shutdown functions that are triggered by the emissions control system on—

(1) agricultural equipment; or

(2) a covered vehicle that is primarily operated north of 59 degrees north latitude, as demonstrated by documentation of commercial operation and maintenance and dispatch records.

SEC. 4. RULE OF CONSTRUCTION.

Nothing in this Act waives compliance with any emissions standard under the Clean Air Act (42 U.S.C. 7401 et seq.). Calendar No. 619

119th CONGRESS

2d Session

S. 3135

A BILL

To require the Administrator of the Environmental Protection Agency to authorize manufacturers of certain vehicles to suspend engine derate or shutdown functions in prolonged cold weather conditions, and for other purposes.

September 16, 2026

Reported with an amendment