ICYMI: EPA’s New Guidance Removes Requirement for Diesel Exhaust Fluid (DEF) Sensors, Saves American Operators Billions
WASHINGTON — On Friday, March 27, 2026, at the White House Great American Agriculture Celebration on the South Lawn, President Trump announced U.S. Environmental Protection Agency (EPA) Administrator Lee Zeldin has issued new guidance making it clear DEF sensors are no longer required, and NOx sensors can be used instead to meet regulatory requirements. Yesterday, while in North Carolina, Administrator Zeldin spoke to local press about this decisive action to address nationwide concerns from farmers, truckers, motor coach operators, and other diesel equipment operators regarding DEF system failures and save Americans billions of dollars annually.
The new guidance is part of a series of Trump EPA actions to provide much needed relief and give American operators countless hours of lost time and productivity back. In August 2025, Administrator Zeldin issued guidance urging manufacturers to revise DEF system software in existing vehicles and equipment to massively reverse deratements that burdened Americans across the country. In February 2026, EPA demanded critical data on DEF system failures from the 14 manufacturers that account for over 80 percent of all products used in DEF systems. The same month, EPA reaffirmed American farmers and operators have the Right to Repair their own equipment, including faulty DEF systems. Additionally, in the near future, EPA will be issuing a new deregulatory proposal to completely remove all DEF deratements for new vehicles and engines. The Trump EPA will never stop pursuing ways to help our farmers.
Read coverage below on the Trump EPA’s commitment to addressing the DEF issue rapidly.
Trucking Dive: EPA Axes Diesel Exhaust Fluid Sensor Requirements
“Diesel vehicles have relied on DEF since 2010 to meet federal emission standards. Over the past 15 years, however, trucking and agriculture businesses have repeatedly reported system malfunctions that make otherwise working equipment inoperable. EPA Administrator Lee Zeldin described the issue as a ‘nationwide disaster,’ citing widespread failures and their operational impact. The agency said it reviewed preliminary manufacturer data on the faulty systems before deciding to remove the sensor requirement, the release said. Trucking industry groups welcomed the reversal.”
Pick-up Truck Talk: Trump EPA Removes Diesel DEF Quality Sensor to Save Farmers, Truckers $13B
“The Trump EPA announced today they are removing the DEF sensor for diesel engines in yet another move to provide financial relief for farmers and truckers. Specifically, the EPA is stating the removal of the urea quality sensor. This sensor has been a constant irritant for diesel engine owners leading to reduced performance on various occasions. Instead, the EPA supports a more reliable NOx sensor to achieve the same results.”
Commercial Carrier Journal: EPA Strikes DEF Sensor Requirement, Seeks to End Derates Over Fluid Quality
“Earlier this year, EPA sought data on DEF system failures from the manufacturers that account for over 80% of all products used in DEF systems. Thus far, the agency said it has received data from 11 of the 14 manufacturers, and less than a month later, the preliminary findings helped inform this new guidance. ‘Failing DEF systems are not an East Coast or West Coast or Heartland issue; it is a nationwide disaster,’ said EPA Administrator Lee Zeldin.”
The Drive: EPA Tells Diesel Engine Makers to Ditch One of the Most Unreliable Emissions Components
“The U.S. EPA has changed its tune on diesel emissions regulation. Whereas it once ruled with a heavy hand, fining engine manufacturers and aftermarket companies at every turn, the agency is now on a deregulation spree with Administrator Lee Zeldin at the helm. The EPA has already called on manufacturers to eliminate immediate power derating when diesel exhaust fluid runs low, and now, the federal organization is strongly encouraging companies to ditch one of modern emissions systems’ most problematic components.”
CDL Life: EPA Removes DEF Sensor Requirement in Move to Save Truckers and Farmers ‘Countless Hours of Lost Time’
“The U.S. EPA announced a major move intended to save farmers, truckers, and other diesel equipment operators ‘billions of dollars in repairs and lost productivity.’ On March 27, 2026, the EPA announced new guidance to remove the Diesel Exhaust Fluid sensor requirement for all diesel equipment in an action that officials say will save Americans ‘countless hours of lost time and productivity.’ The guidance was issued after a February 3, 2026, call from the EPA for manufacturers to submit data on DEF system failures.”
Landline Media: EPA Takes Aim at DEF Sensors That Sideline Truckers
“When it comes to equipment, one of the biggest complaints truck drivers have is with diesel exhaust fluid. It’s a gripe the EPA has been hearing and addressing. DEF has been a thorn in the side of truck drivers and farmers for years. In addition to reports of poorer engine qualities, deratings or inducements can shut down a diesel engine with little to no warning. Last August, EPA Administrator Lee Zeldin delivered his first gift to truck drivers struggling with DEF system failures.”
Heavy Duty Trucking: EPA Targets DEF Sensor Failures Behind Truck Derates
“In the Trump administration’s latest steps to address the frustrations that truckers have with diesel exhaust sensors and so-called ‘de-rates’ when DEF runs out or is diluted, the EPA is allowing engine manufacturers to use a different type of sensor than the frustrating DEF sensors...The EPA has been working since last August to address the sudden speed losses and shutdowns caused by DEF system failures, saying they compromise safety and productivity for truckers as well as for farmers.”
WITN: EPA Administrator Visits Rocky Mount to Discuss Diesel Engine Regulations
“The EPA’s administrator visited Rocky Mount to discuss plans to help farmers who are drawing concern from some regarding the environment. EPA Administrator Lee Zeldin highlighted diesel engine fluid regulations during a press conference on Monday. ‘The farmer would tell me the story about how they have had tractors stop four times in harvest over the course of the past year, and that the fluid was in the system, but the tractor would still stall because of a faulty depth sensor,’ Zeldin said. Because of conversations like those, he said they plan to propose eliminating derates, or enforced reductions in a diesel engine’s power and speed altogether.”
AgWeb: Trump Signals More DEF Rollbacks, Pushes Manufacturers to Lower Equipment Costs
“In front of a gathering of farmers, ranchers and growers at the White House, President Trump and EPA announced new guidance that will remove the DEF sensor requirements, which the Small Business Administration estimates will save farmers $4.4 billion a year and translate into $13.79 billion for Americans. Administrator Lee Zeldin says the move impacts farmers, truckers, motor coach operators and other diesel equipment operators.”
Freight Waves: DEF Sensors no Longer Required on Trucks, Other Diesel Equipment: EPA
“...‘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,’ EPA Administrator Lee Zeldin said in the EPA’s prepared statement. ‘Americans are justified in being fed up with failing DEF system issues.’ That statement said ‘preliminary review of the warranty data suggests that DEF sensor failures are a significant source of warranty claims and DEF-related inducement.’ EPA said the sensors are more formally known as urea quality sensors. The new guidelines also said the sensors can be switched over to nitrous oxide sensors.”
Spectrum News: EPA Ends Diesel Exhaust Fluid Sensor Requirements to Help Farmers and Truckers Save Money
“EPA Administrator Lee Zeldin says the removal of diesel exhaust fluid sensors is a long time coming for people in the industry. ‘I was blown away. How many people were complaining about the implementation of diesel exhaust fluid system, standards requirements,’ Zeldin said. ‘It’s about being responsive to the concerns. And farmers and others who have reached out to us.’ Nash County farmer Sue Leggett says farmers like herself are happy about this change because DEF technology impacted their day-to-day work in a negative way.”
The Fence Post: Zeldin: EPA Removes Diesel Exhaust Fluid Requirement
“EPA Administrator Lee Zeldin has announced that EPA has removed the requirement that diesel equipment contain Diesel Exhaust Fluid (DEF) sensor equipment...‘EPA understands that sudden speed losses and shutdowns caused by DEF system failures that compromise safety and productivity are unacceptable and problematic,’ the announcement said.”
Successful Farming: EPA Eliminates DEF Sensor Requirement, Projects Saving Farmers $4.4 Billion Annually
“EPA on Friday announced the removal of the DEF sensor requirement for all diesel equipment, stating that the sudden speed losses and shutdowns caused by DEF system failures unacceptably compromise safety and productivity. The agency vowed to continue to pursue all legal avenues to address American’s complaints and keep farmers from losing days in the field.”
Transport Topics: EPA Moves to Address DEF System Failures
“...‘Americans are justified in being fed up with failing DEF system issues,’ EPA Administrator Lee Zeldin said in a March 27 news release. ‘EPA understands this is a massive issue and has been doing everything in our statutory power to address this.’ Under the agency’s updated guidance, manufacturers will be permitted to replace Urea Quality Sensors with nitrogen oxide sensors. The guidance also said that approved NOx sensor-based software updates can be installed on existing engines without being treated as illegal tampering under the Clean Air Act.”
Texas Farm Bureau: EPA Takes Additional Action to Address DEF Failures
“U.S. President Donald Trump made the announcement at an event celebrating American agriculture on the White House lawn Friday, March 27. ‘We had a ridiculous Washington restriction called the Diesel Exhaust Fluid requirement. It was a basic disaster,’ Trump said. ‘We’re announcing new guidelines drastically limiting these ridiculous DEF rules, saving farmers and consumers billions and billions of dollars.’ According to EPA guidance, manufacturers can now stop inaccurate DEF system failures by removing traditional emission sensors, or urea quality sensors, and switching to nitrous oxide sensors.”
ACT News: EPA Targets DEF System Failures, Offering Relief for Heavy-Duty Truck Operations
“For heavy-duty trucking operations, a single sensor failure can take a truck off the road, derail a delivery, and trigger cascading costs across an entire network. That reality has defined the industry’s experience with DEF systems in recent years, and it is exactly what the U.S. EPA is now attempting to address. In its latest action, EPA announced it is removing the requirement for DEF quality sensors, a change intended to reduce unnecessary derates, breakdowns, and downtime tied to malfunctioning sensors, while maintaining overall emissions compliance, according to the agency.”
Michigan Farm News: DEF Sensors Dropped: What To Know About EPA’s $14B Decision
“... President Donald J. Trump announced the DEF sensor rollback during the Great American Agriculture Celebration, held on the White House lawn March 27, saying his administration is ‘drastically limiting these ridiculous DEF rules, saving farmers and consumers billions.’ According to EPA, those savings net farmers $4.4 billion a year in repairs and lost productivity and provide $13.79 billion a year of savings to Americans.”
The Trucker: What Truckers Think About EPA’s Decision to Drop DEF Sensor Requirement
“...According to the EPA, removing DEF sensors will provide immediate relief and save billions of dollars in repairs and lost productivity. According to the U.S. Small Business Administration, the new guidance will save farmers $4.4 billion a year and this action will provide $13.79 billion a year of savings to Americans.”
Truck News: EPA Removes DEF Sensor Requirement for Diesel Engines
“... EPA said the DEF measure does not weaken or remove emissions standards, but instead ‘ensures that those standards are met in a way that actually works in the real world.’... The agency also affirmed that approved NOx sensor-based software updates can be installed on existing engines without being treated as illegal tampering under the Clean Air Act. In the coming months, EPA said it will issue a new deregulatory proposal that will completely remove all DEF deratements for new vehicles and engines.”
Power Progress: US EPA Removes Requirement for DEF Sensors on Diesel Engines
“... The move was made to help eliminate issues caused by faulty DEF sensors. Failure of these parts can put diesel engines into ‘limp home’ mode, effectively taking the vehicle or machine out of service until the part can be replaced. Due to the cost of repairs and reduced productivity, the government puts forward the change will save farmers about $4.4 billion savings across all American diesel users could reach $13.79 billion per year.”
Progressive Farmer: EPA Issues New DEF Guidance
“Farmers frustrated with DEF shutdowns may see fewer breakdowns under new EPA guidance, though the agency’s new guidance on DEF stopped short of eliminating the emissions systems altogether. EPA did not eliminate the DEF rules, which have been a problem for farmers because of failure rates, but issued new guidance last week, giving major machinery manufacturers more flexibility in how they monitor exhaust emissions. EPA will now allow equipment manufacturers to use nitrous oxide (NOx) sensors to reduce problems with tractors and semi-trucks ‘de-rating’ during operations.”
NewsNation: Trump Hosts 800+ Farmers at White House, Announces Agriculture Push
“... Trump also announced that the EPA is removing the diesel exhaust fluid, or DEF, sensor requirement for all diesel equipment — a change the administration says will save farmers $4.4 billion annually and provide $13.79 billion in total annual savings to American operators. DEF systems, which have been required on most diesel trucks and farm equipment since 2010, have drawn complaints for triggering sudden speed reductions or shutdowns when sensors malfunction. Friday’s guidance allows manufacturers to switch from traditional urea quality sensors to NOx sensors, which the EPA says will significantly reduce erroneous failure alerts.”
Overdrive: Trump, EPA, Congress Hope to Save Truckers Billions with Diesel Liberation Act, New Guidance
“President Donald Trump on Friday announced the Environmental Protection Agency was removing the DEF sensor requirement for all diesel equipment used by farmers, truckers, and bus drivers... ‘The EPA has significant concerns about ongoing reports of DEF inducements due to the failure of [Urea Quality Sensors] impacting the owners and operators of diesel-powered equipment unnecessarily,’ EPA’s guidance said.”
WRAL News: EPA Diesel Rollback Could Save Farmers Billions: Clean-Air Advocates Worry About Risks
“New regulatory guidance for diesel engines could save U.S. industries billions of dollars for farmers and truckers, but clean-air advocates say it could pose a significant risk to public health. Lee Zeldin, the head of the U.S. Environmental Protection Agency, was in Rocky Mount Monday to tout his agency’s decision last week to remove a requirement for exhaust fluid sensors on diesel equipment. The move comes in response to concerns raised by farmers, truckers, motor coach operators and other diesel equipment operators over diesel exhaust sensor failures that can eat into productivity, the EPA says.”