Engine Technology Forum Launches SCR, DEF Resource Center Amid Emissions Debate Cummins, Paccar Ease DEF Derates After EPA Guidance Updated diesel engine software gives truck operators more time to address emissions-system issues while staying compliant with EPA emissions standards. - Cummins and Paccar have adjusted their diesel engine software following new guidance from the EPA. - The updated software allows truck operators extended time to solve emissions-system problems. - Compliance with EPA emissions standards is maintained under the new adjustments. *Summarized by AI Cummins and Paccar announced software changes to their diesel engines to allow truckers to continue to operate longer after a truck’s sensors have determined an empty diesel exhaust fluid tank or other emissions system problems. They join Daimler Truck North America, which recently announced changes to Detroit engines, in making changes to reflect revised Environmental Protection Agency guidance on DEF inducements. Diesel exhaust fluid is used in selective catalytic reduction technology to convert nitrogen oxides (NOx) in engine exhaust into nitrogen and water, helping meet EPA emissions standards. DEF inducements are safeguards that reduce vehicle speed and power when emissions system issues are detected. Common issues include low DEF levels or reduced selective catalytic reduction system performance. They prompt, or "induce," drivers to correct the issue by refilling the DEF tank, repairing faulty sensors, or performing a system regeneration. These are commonly known as "DEF derates." What EPA Said About DEF Derates Last August, the EPA announced new guidance for manufacturers to increase the time truckers have to refill the DEF tank or make repairs. The agency also announced that starting with model year 2027, all new diesel on-road trucks must be engineered to avoid sudden and severe power loss after running out of DEF. To address the problem for vehicles already in use, EPA’s guidance allowed