EPA May Remove Limp Mode for DEF-Low Diesel Trucks
The United States Environmental Protection Agency (EPA) is reconsidering its policies regarding diesel trucks that utilize Diesel Exhaust Fluid (DEF). Under the current administration, there has been a noticeable shift from stringent penalties to a focus on deregulation.
Possible Removal of Limp Mode for Diesel Trucks
Recently, EPA Administrator Lee Zeldin announced plans that may eliminate the immediate “limp mode” restrictions for diesel trucks when DEF levels are low. Traditionally, these restrictions would limit vehicle power and speed to ensure compliance with emissions regulations. However, this policy change might allow trucks to operate normally for extended periods even when DEF is insufficient.
Request for Manufacturer Data
On Tuesday, the EPA called for information from the top 14 manufacturers of on-road and off-road vehicles equipped with DEF systems. The agency is evaluating warranty claims, failure rates, and repair records for model years 2016, 2019, and 2023. This data will help determine if emissions system-related issues are concentrated in specific model years or are widespread across the board.
- Manufacturers must provide requested data within 30 days.
- Failure to comply could lead to additional inquiries or penalties.
History of Emissions Regulations
Zeldin’s recent direction comes after several reported failures of DEF systems by truck drivers across all 50 states. In August 2025, he announced significant changes aimed at reversing previous deratings that affected truck performance when DEF tanks were low.
Starting with the 2027 model year, trucks would be allowed to operate normally for up to 4,200 miles or 80 hours with low DEF levels before being limited to a maximum speed of 45 mph. This change has already provided some relief for diesel truck owners.
Implications of Potential Changes
The current assessment by the EPA could lead to a significant change in how diesel pickups are managed regarding DEF. The agency indicated it is investigating whether the derate requirements may no longer be necessary for compliance.
If implemented, this would allow truck owners greater freedom, potentially improving vehicle reliability and performance. This change comes amidst ongoing complaints from truck drivers who believe DEF-related restrictions negatively impact their vehicles’ fuel economy and efficiency.
For further updates or inquiries, individuals can reach out directly to the article’s author. The future of diesel truck regulations is evolving, and the outcomes of these assessments could influence the market considerably.
