Cold Weather Diesel Reliability Act of 2025

This bill allows diesel vehicles operating in extremely cold regions to temporarily disable engine shutdowns and emissions-related functions when temperatures drop below freezing, ensuring critical transportation and emergency services remain operational. It grants year-round exemptions from diesel exhaust fluid (DEF) system requirements for vehicles primarily operating north of 59°N latitude or in areas where DEF systems become impractical due to prolonged freezing conditions. The exemptions apply only during cold weather (below freezing) for engine derates/shutdowns or permanently for DEF systems, without altering emissions standards outside these specific conditions. It directly affects diesel vehicles used by emergency responders, rural transport, and critical infrastructure in Arctic or sub-Arctic regions. The EPA must implement these changes within 180 days of the bill’s enactment.