US Environmental Protection Agency Administrator Lee Zeldin has announced guidance to prevent sudden shutdowns in diesel exhaust fluid systems. The current regulations have caused significant disruptions in agriculture and construction.
The new rules will apply to model year 2027 on-road trucks, requiring them to be designed so that running out of DEF does not cause severe power losses. Manufacturers must also make software changes to prevent DEF derating on existing vehicles.
The change is expected to save family-run farms an estimated $727 million annually. Zeldin’s plan extends the time between system failures and capacity reduction, but will not completely eliminate DEF systems.
The announcement comes as EPA officials recently proposed to ditch a long-held stance that greenhouse gas emissions threaten the environment and public health.
Source: https://www.kcrg.com/2025/08/12/epa-administrator-announces-power-loss-fix-diesel-exhaust-fluid-systems