Washington, D.C. – Representatives Julie Fedorchak (R-ND), Don Davis (D-NC), Michelle Fischbach (R-MN), Jack Bergman (R-MI), and Brad Finstad (R-MN) today introduced the Diesel Engine Flexibility (DEF) Act. The legislation creates a 10-year statutory safe harbor for Environmental Protection Agency (EPA) guidance issued in 2025 and 2026, helping reduce unnecessary engine shutdowns caused by faulty DEF sensors while maintaining emissions protections.
"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," Fedorchak said. "The DEF Act brings commonsense 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."
“When a tractor or truck sits idle, farmers, truckers, manufacturers, and small businesses feel the pain. They rely on reliable diesel-powered equipment every day. The Diesel Engine Flexibility Act would reduce unnecessary downtime caused by faulty emissions sensors while keeping every existing emissions standard in place, said Davis. “It's a practical solution that supports jobs, strengthens our rural economy, and helps keep America fed and our communities growing.”
“Due to previous EPA guidelines, our nation’s farmers were required to rely on faulty DEF sensors and mandates. As a fourth-generation farmer, I am proud to join Congresswoman Fedorchak in introducing the DEF Act, which will codify the recently improved EPA guidance for diesel engines and vehicles, providing increased flexibility and clarity for folks in farm country – no matter the administration,” said Finstad.
Faulty DEF sensors and rigid EPA engine shutdown requirements are costing farmers, truckers, and operators time and money, often through no fault of their own. The DEF Act fixes this by strengthening monitoring capabilities, limiting engine shutdown and performance reductions, and giving independent technicians the legal clarity to service their customers’ equipment. Specifically, the legislation:
Creates a 10-year statutory safe harbor for EPA diesel emissions guidance issued in 2025 and 2026.
Allows EPA to continue approving software updates, diagnostic improvements, recalls, and other administrative actions consistent with the guidance.
Requires future emissions standards to include meaningful lead times, including at least three model years of applicability and five years before taking effect.
Directs EPA to consider reducing unnecessary shutdowns, derates, and operational disruptions when developing future emissions regulations.
Without congressional action, these improvements remain subject to future administrative changes. The DEF Act provides long-term certainty for equipment owners, manufacturers, and technicians.