During the White House Great American Agriculture Celebration on March 27, President Donald Trump announced action by the U.S. Environmental Protection Agency to address nationwide concerns from farmers, truckers, motor coach operators and other diesel equipment operators regarding Diesel Exhaust Fluid (DEF) system failures. EPA is removing the DEF sensor requirement for all diesel equipment.

According to the U.S. Small Business Administration (SBA), this new EPA guidance will save farmers $4.4 billion a year and will save Americans $13.79 billion a year. The announcement does not weaken or remove emissions standards, according to the EPA.

Since 2010, most on-road diesel trucks and many types of nonroad equipment, such as tractors and construction machinery, have used selective catalytic reduction systems that inject DEF into exhaust streams to reduce nitrogen oxide gas emissions. EPA understands sudden speed losses and shutdowns caused by DEF system failures compromise safety and productivity. Preliminary review of warranty data suggests that DEF sensor failures are a significant source of warranty claims and DEF-related inducement.

On Feb. 3, EPA demanded critical data on DEF system failures from the manufacturers that account for more than 80% of all products used in DEF systems. As of last week, the agency has received data from 11 of the 14 manufacturers.

EPA also affirmed that approved nitrogen oxide gas, sensor-based software updates can be installed on existing engines without being treated as illegal tampering under the Clean Air Act. This is in line with EPA’s February 2026 Right to Repair clarification guidance, which removed a major barrier keeping farmers from fixing their faulty DEF systems in the field.

Additionally, EPA announced it will continue reviewing data collected from manufacturers and use this information to identify opportunities to improve the emission systems for the American people beyond the actions taken to date.