Bipartisan legislation sponsored on July 9 by U.S. Rep. Julie Fedorchak (R-ND) would amend the Clean Air Act to preserve regulatory stability for diesel motor vehicles and engines, while also providing long-term certainty for equipment owners, manufacturers, and technicians.
The Diesel Engine Flexibility (DEF) Act, H.R. 9618, which has four original cosponsors, including U.S. Rep. Don Davis (D-NC), would create a 10-year statutory safe harbor for Environmental Protection Agency (EPA) guidance issued in 2025 and 2026 to help reduce unnecessary engine shutdowns caused by faulty DEF sensors.
The measure also would maintain EPA emissions protections, according to a bill summary provided by Rep. Fedorchak’s staff.
“Farmers, truckers, and equipment operators depend on reliable equipment to keep our economy moving. They shouldn’t be sidelined by faulty sensors or unnecessary shutdowns that have nothing to do with actual emissions,” Rep. Fedorchak said. “The DEF Act brings common-sense certainty by preserving the EPA’s updated guidance in law while creating a stable regulatory framework for the next decade.
“It gives manufacturers, operators, and independent technicians the certainty they need to invest, innovate, and keep equipment running without sacrificing emissions performance,” added the congresswoman.
Specifically, H.R. 9618 would strengthen monitoring capabilities, limit engine shutdown and performance reductions, and give independent technicians the legal clarity to service their customers’ equipment.
Under the bill, the EPA also would continue approving software updates, diagnostic improvements, recalls, and other administrative actions consistent with the guidance, and would require future emissions standards to include meaningful lead times, including at least three model years of applicability and five years before taking effect, the summary says.
“The Diesel Engine Flexibility Act would reduce unnecessary downtime caused by faulty emissions sensors while keeping every existing emissions standard in place,” said Rep. Davis. “It’s a practical solution that supports jobs, strengthens our rural economy, and helps keep America fed and our communities growing.”