S. 3135: Cold Weather Diesel Reliability Act of 2025

This bill, known as the Cold Weather Diesel Reliability Act of 2025, aims to address operational challenges faced by diesel vehicles and equipment in extremely cold weather conditions. Here are the main points of the bill:

Key Findings

• Diesel vehicles are essential for critical transportation and emergency services in cold regions.
• In rural areas with long periods of freezing, there are significant challenges regarding diesel exhaust fluid (DEF) – its storage, supply, and functionality can be unreliable.
• Automatic engine shutdowns caused by emissions control malfunctions in cold weather can pose severe risks to human safety.
• Emissions regulations under the Clean Air Act should not compromise human safety or critical mobility.

Definitions

• Administrator: Refers to the Administrator of the Environmental Protection Agency (EPA).
• Covered Manufacturer: A manufacturer defined under the Clean Air Act that produces covered vehicles or engines.
• Covered Vehicle: An on-highway diesel vehicle or nonroad diesel equipment.

Diesel Engine Emissions Relief

The bill proposes the following measures related to diesel engine operations in cold weather:

Cold Weather Sensor Mitigation Measures

• Within 180 days of the bill's enactment, the EPA Administrator must revise relevant regulations to allow manufacturers of covered vehicles to disable engine derate (power reduction) or shutdown functions triggered by emissions control faults when the temperature is at or below 0°C (32°F).
• This suspension of functions is permitted under two conditions:
  • The engine must return to normal operations once temperatures rise above 0°C.
  • Maintaining maximum engine performance at low temperatures is crucial to avoid dangers or equipment failures in remote areas.

Relief for Regions with Prolonged Freezing Conditions

• Also within 180 days of enactment, the EPA will revise regulations to grant year-round exemptions from diesel exhaust fluid system requirements for covered vehicles:
  • Primarily operated north of 59 degrees north latitude.
  • Experiencing operational conditions that involve prolonged exposure to temperatures below the freezing point of diesel exhaust fluid or where using such systems is impractical.
• This exemption means that certain covered vehicles will not need to have derate or shutdown functions related to diesel exhaust fluid system issues.

Compliance with Emission Standards

The bill clarifies that it does not waive compliance with any emission standards under the Clean Air Act except for the temporary provisions allowed in this act regarding cold weather operations and the exemptions mentioned above.

Relevant Companies

• DE (Deere & Company) - Potentially impacted as they manufacture agricultural equipment that relies on diesel engines, affecting their operational capabilities in cold regions.
• CMI (Cummins Inc.) - As a manufacturer of diesel engines, they may be directly affected by changes in emissions regulations, particularly regarding cold weather operations.
• PCAR (PACCAR Inc.) - Produces trucks and transportation equipment that may benefit from exemptions under this bill, impacting their market competitiveness in cold weather regions.