Committee holds hearing on Sullivan’s Cold Weather Diesel Reliability Act

When temperatures in Interior Alaska plunge to -40°F and beyond, the diesel engines keeping the state’s supply chain alive don't just struggle—they freeze solid. For truck drivers, school bus drivers, and heavy equipment operators, this isn’t just a maintenance headache; it’s a high-stakes race against hypothermia and a fight against a "compliance trap" where federally mandated emission systems often shut down vehicles when they are needed most.

To address the issues with modern diesel emissions malfunctioning in sub-zero temperatures, Senators Dan Sullivan (R-AK) and Cynthia Lummis (R-WY), have introduced the Cold Weather Diesel Reliability Act of 2025.

The proposed legislation seeks to amend EPA regulations to prevent diesel vehicles and equipment from automatically shutting down or losing power (derating) due to frozen Diesel Exhaust Fluid (DEF) systems in extreme cold. By addressing the failure of DEF systems to operate effectively in temperatures below 12°F (-11°C), this bill aims to prevent occupational hazards, equipment failure, and the loss of critical transportation—such as snow plows—in remote areas.

Some key provisions within the legislation include a proposal for year-round DEF system exemptions for heavy-duty vehicles/equipment in northern regions and instructs the EPA to allow the disabling of automatic engine derates or shutdowns caused by frozen DEF systems. The legislation would also require the EPA to update regulations within 180 days to reflect cold-weather operational realities, ensuring the reliability of essential diesel equipment and prevents hazardous conditions in extreme cold.

During the March 11 Senate hearing, Alaska Department of Transportation and Public Facilities (DOT) Commissioner Ryan Anderson testified that federal diesel regulations are causing life-threatening failures in cold-weather states. He noted that 80% of maintenance issues for Alaska’s equipment fleet over the last two years stem from DEF system failures in extreme cold. Commissioner Anderson emphasized that Senator Sullivan’s bill is vital to protecting the emergency vehicles, commercial trucks, and infrastructure machinery that Alaskans depend on to survive winter

During the hearing, Sen. Sullivan noted that his legislation was the result of hearing from Alaskans who deal with these problems, including from one trucking company about one of its trucks operating on the Dalton Highway—a 400 mile stretch of road leading to Prudhoe Bay, with only one gas station. It was 45 degrees below zero and the trucker was driving through a blizzard when it suddenly lost power.

“The driver went from highway speed to crawling along at about five miles per hour in the middle of a blizzard while hauling a heavy load through mountain terrain,” said Senator Sullivan. “There’s no cell service along most of the Dalton Highway. He had to call dispatch on a satellite phone while idling in brutal wind chills just to keep the truck from freezing solid. Hours later, another driver finally reached him and helped him out. He survived—but the load had to be dropped, and the company paid about $15,000 just to tow the truck back to Fairbanks.”

The bill now faces committee review to address safety issues over cold-weather shutdowns while balancing environmental requirements. Lawmakers are debating the bill's necessity, as the EPA is already enforcing 2027 rules that compel new diesel trucks to avoid sudden power loss, potentially duplicating or conflicting with the proposed legislation

If approved, the bill moves to the Senate floor, and subsequently, a similar version must be passed by the House before going to the President for signature.