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119-hr-6250119th Congress

Cold Weather Diesel Reliability Act of 2025

Sponsored By: Representative Begich, Nicholas J. [R-AK-At Large]

Introduced

Summary

Allow diesel engines to keep running in extreme cold by suspending emissions-triggered derates and exempting diesel exhaust fluid rules in high-latitude or freezing operations.

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  • Drivers and operators in very cold regions would be able to avoid engine derates or shutdowns at or below 0 degrees Celsius, helping prevent strandings and loss of essential transport in remote areas.
  • Covered manufacturers would be allowed to disable inducement-related derate or shutdown functions in those cold conditions and to omit derate triggers tied to diesel exhaust fluid systems for qualifying vehicles.
  • Remote worksites, emergency responders, and communities north of 59 degrees north latitude would get year-round relief from DEF requirements when documentation shows primary operation there or when prolonged freezing makes DEF use impractical.
  • The Environmental Protection Agency would be required to revise Clean Air Act regulations within 180 days to create these narrow cold-weather allowances while keeping standard emissions rules in place outside the authorized modes.

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Bill Overview

Analyzed Economic Effects

2 provisions identified: 1 benefits, 0 costs, 1 mixed.

Clean air rules mostly unchanged

This bill would keep Clean Air Act emission rules in place. Only two narrow exceptions would apply: a cold‑weather mode at or below 0°C and a DEF exemption for certain northern or long‑freezing operations. It would define who is covered: EPA as the Administrator, covered manufacturers, and covered vehicles like on‑highway diesel trucks and nonroad diesel equipment. This would keep relief narrow and targeted.

Cold-weather relief for diesel engines

Within 180 days, EPA would need to change rules so makers can suspend engine derates or shutdowns at or below 0°C when emission faults trigger them. Engines would go back to normal controls when it is above 0°C. At 0°C or below, full power could continue if needed to prevent danger, equipment failure, or loss of vital transport in remote areas with little support. Only manufacturers could turn off these inducements, not drivers. Year-round, some vehicles could get a DEF-system exemption if they run mainly north of 59°N or face long freezing that makes DEF use impractical. Records of operation, domicile, or maintenance could be used to prove it. The DEF relief would also remove any required derate or shutdown for DEF faults or missing fluid.

Sponsors & CoSponsors

Sponsor

Begich, Nicholas J. [R-AK-At Large]

AK • R

Cosponsors

  • Rep. Maloy, Celeste [R-UT-2]

    UT • R

    Sponsored 4/21/2026

Roll Call Votes

No roll call votes available for this bill.

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