The U.S. Environmental Protection Agency announced on June 12 a new action to address complaints about Diesel Exhaust Fluid (DEF) system failures by removing the DEF sensor requirement for all diesel equipment. The agency said this change is expected to save American farmers and truckers over $13 billion annually in repairs and lost productivity.
According to the EPA, sudden speed losses and shutdowns caused by DEF system failures have compromised safety and productivity for operators across the country. The new guidance will provide immediate relief by eliminating the need for traditional emission sensors, known as Urea Quality Sensors, and switching to nitrous oxide (NOx) sensors instead. "Failing DEF systems are not an east coast or west coast or heartland issue; it is a nationwide disaster. I have heard from truck drivers, farmers, and many others complaining about DEF and pleading for a fix in all 50 states I visited during my first year as EPA Administrator," said EPA Administrator Lee Zeldin. "Americans are justified in being fed up with failing DEF system issues. EPA understands this is a massive issue and has been doing everything in our statutory power to address this. Today, we take another step in furthering our work by removing DEF sensors. Farmers and truckers should not be losing billions of dollars because of repair costs or days lost on the job."
U.S. Secretary of Agriculture Brooke L. Rollins said, "Since joining the Trump Administration, I have worked hand in glove with Administrator Zeldin and consumers who have been hampered by faulty Diesel Exhaust Fluid systems. Through this partnership, we have seen historic actions taken to rectify the problems everyday Americans are facing in their trucks and non-road equipment." Rollins continued: "I’m proud to see the EPA responding to the demands of these consumers and working to implement real change to solve these issues. The action today will allow engine manufacturers to update their systems to monitor the pollutants we are targeting rather than the Diesel Exhaust Fluid itself which has caused many of the system failures. This powerful step will provide much needed relief, but we will continue to work towards a solution that protects the environment while eliminating damages to farmers and truckers nationwide."
SBA Administrator Kelly Loeffler added: "Few small businesses have been hit harder by the Green New Scam than those who make up America’s great agriculture industry, where massive regulatory burdens have crushed family farms and driven up grocery costs." Loeffler also said: "Today, by eliminating DEF mandates, the Trump Administration is taking yet another step to free up hardworking Americans to focus on the vital work of feeding, clothing, building, and fueling our nation. I applaud Administrator Zeldin for his leadership on this issue, and I look forward to our continued collaboration to cut red tape for small businesses across the U.S. food supply chain."
The EPA said that its preliminary review found that DEF sensor failures are a significant source of warranty claims among diesel vehicle operators nationwide. The agency's new guidance clarifies that under existing regulations manufacturers can replace traditional emission sensors with NOx sensors without violating Clean Air Act tampering rules.
These changes follow previous guidance issued by EPA since August 2025 calling on manufacturers to revise software in existing vehicles so that sudden speed reductions due to DEF faults would be less severe or delayed over longer periods—allowing operators more time before experiencing operational limitations.
The agency emphasized that today's announcement does not weaken emissions standards but aims instead at ensuring compliance through more reliable technology while reducing economic hardship for operators according to the official roster page.
