WASHINGTON, D.C. – EPA Administrator Lee Zeldin on March 27 introduced new guidance for diesel exhaust fluid systems, which he said would cut costs and reduce system failures.

“Failing diesel exhaust fluid systems are not an East Coast or West Coast, or Heartland issue; it is a nationwide disaster,” Zeldin said. “I have heard from truck drivers, farmers and many others complaining about diesel exhaust fluid systems, and pleading for a fix in all 50 states I visited during my first year as EPA administrator.

“Americans are justified in being fed up with failing diesel exhaust fluid system issues,” he added. “The 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 diesel exhaust fluid system sensors. Farmers and truckers should not be losing billions of dollars because of repair costs, or days lost on the job.”

He said this update allows diesel equipment manufacturers to move away from traditional systems’ quality sensors and instead use other technologies, such as nitrogen oxide sensors, which the EPA’s preliminary review of manufacturer warranty data indicated are significantly less prone to generating the fault readings that have been causing most diesel exhaust fluid systems-related deratements.

According to the EPA, deratements are automatic, mandatory reductions in a diesel engine’s power, torque, or speed triggered by emissions system failures, specifically in the diesel exhaust fluid system.

The EPA said these changes aim to reduce system failures, and improve the reliability of farm equipment. When the sensor fails or detects a problem, machines may enter derate mode, or deratement, the EPA added.

The EPA said this new guidance will help save farmers $4.4 billion a year in repairs and lost productivity, and produce a broader savings of $13.79 billion to the U.S. economy. Since 2010, most diesel engines, including those used in agriculture, have relied on selective catalytic reduction systems, which inject diesel exhaust fluid into the exhaust stream to reduce emissions, and meet federal air quality standards, the EPA added.

In August 2025, Zeldin issued guidance urging manufacturers to revise diesel exhaust fluid system software in existing vehicles and equipment to massively reverse deratements he said “burdened Americans across the country.”

In February 2026, the EPA demanded critical data on diesel exhaust fluid system failures from the 14 manufacturers that account for over 80 percent of all products used in diesel exhaust fluid systems. The same month, the EPA said American farmers and operators have the “right to repair” their own equipment, including faulty diesel exhaust fluid systems.

While several farm organizations declined to comment, Courtney Briggs, American Farm Bureau Federation senior director of government affairs, told Farm World, “We’re appreciative of the EPA acknowledging that diesel engine fluid system sensors often require costly repairs that slow farmers down during critical times of planting and harvest.

“We hope this is an important step toward eliminating unnecessary diesel engine fluid system requirements from agricultural equipment altogether,” she said.

In the near future, the EPA said it will be issuing a new deregulatory proposal to completely remove all diesel exhaust fluid deratements for new vehicles and engines.