Senate committee advances Sullivan cold-weather diesel bill on 10-9 vote

Truckers, plow operators and state fleet mechanics in Alaska moved a step closer to relief from a federal rule that shuts diesel engines down in deep cold. The Senate Environment and Public Works Committee voted 10-9 on Wednesday, Sept. 16, 2026, to report out Sen. Dan Sullivan's Cold Weather Diesel Reliability Act. The bill would direct the Environmental Protection Agency to end automatic engine shutdowns during extreme cold.

The committee first adopted a substitute amendment by voice vote. Chairman Shelley Capito said the substitute was offered as the base text in response to feedback received after the bill's introduction. The measure now awaits floor scheduling. The full Senate has not voted on it.

Sullivan tied the vote to equipment Alaskans depend on through winter. Diesel exhaust fluid, or DEF, freezes at 12 degrees Fahrenheit. Emissions systems can cut engine power when the fluid fails or a sensor reads a fault. "Even with onboard heaters, these systems can't compete with -40°F weather, which we often see in Alaska," Sullivan said. He said the failures strand drivers on remote highways without cell service, and that the problem reaches fire trucks, school buses and airport plow equipment.

At the committee's March hearing on the bill, Alaska Transportation Commissioner Ryan Anderson testified that "DEF-related failures cause up to 80% of the state of Alaska's fleet maintenance issues," Sullivan said. Wyoming Farm Bureau Federation's Todd Fornstrom also testified at that hearing. So did the Natural Resources Defense Council's John Walke. The group has said the existing shutdown framework serves emissions-control and safety goals together, and that changing the requirements could weaken compliance and increase pollution from the affected engines.

Ranking Member Sheldon Whitehouse voted no. He said the bill skipped the negotiation the committee's other two measures went through. "With real regret, because I think there may have been a way to cure the over-breadth problem, I will oppose it," Whitehouse said. He added, "Perhaps we can keep working towards a bipartisan solution."

Sullivan and Sen. Cynthia Lummis introduced the bill in November 2025. Sullivan said he wants a bipartisan path before it reaches the floor.