On September 16, 2026, the Senate Environment & Public Works (EPW) Committee passed the Cold Weather Diesel Reliability Act introduced by Senators Dan Sullivan (R-Alaska) and Cynthia Lummis (R-Wyoming). The legislation directs the Environmental Protection Agency (EPA) to update its regulations to prevent the automatic shutdowns (or ‘derates’) caused by cold-related emissions faults, and to provide year-round exemptions from DEF system requirements for vehicles and equipment that operate primarily in cold weather climates. The committee’s passing of the legislation follows the presidential pardon of Wasilla diesel mechanic MacKenzie “Mac” Spurlock on July 3 of this year.
Mac Spurlock had been charged with criminal tampering after he removed air-pollution controls on vehicles with diesel engines. Sen. Sullivan wrote a letter to the President, requesting Spurlock’s pardon because his actions were a matter of “safety and survival.”
Under current EPA regulations, diesel trucks and heavy equipment are required to use emissions systems that can trigger engine shutdowns if the system detects a fault. In cold weather, these emissions components—including but not limited to diesel exhaust fluid (DEF)—often struggle to reach or maintain proper operating temperatures, causing the system to register faults even when the engine itself is running normally. These systems have created life-threatening situations for truckers, including one trucker whose vehicle shut down in a blizzard on the Dalton Highway, a 400-mile stretch of road leading to Prudhoe Bay with only one gas station.
“When a truck or piece of heavy equipment is forced by EPA mandates to shut down in extreme cold because of a faulty sensor not made for the cold, it’s not just an inconvenience—it can quickly become a life-threatening situation,” said Sen. Sullivan. “For too long, the men and women who keep Alaska moving have been forced to contend with one-size-fits-all EPA diesel mandates that simply don’t work in our state. I want to thank my committee colleagues today for joining me in taking an important step toward fixing this issue once and for all. The Cold Weather Diesel Reliability Act will bring common sense to EPA rules and ensure that trucks and heavy equipment can continue operating safely and reliably in the nation’s coldest regions.”
Listen to Sen. Sullivan’s comments to the committee here:
