Kenworth Truck Company and Peterbilt Motors Company are implementing software updates for vehicles equipped with Paccar MX-11 and MX-13 engines. The changes are designed to align with revised guidance from the U.S. Environmental Protection Agency regarding diesel exhaust fluid inducements. The updates aim to improve operational reliability and reduce disruptions for customers.
The software modifications adjust how the vehicles handle speed and power limitations when emissions system issues are detected. Specifically, the final inducement speed limit will increase from 5 mph to 25 mph. Additionally, the timeline for reaching this speed limit will extend from 4 hours to 160 hours for component-related problems or fluid quality issues.
DEF inducements function as safeguards that reduce vehicle speed and power when emissions system faults are identified. Common triggers include low diesel exhaust fluid levels or reduced performance in the selective catalytic reduction system. These measures prompt drivers to refill the fluid tank, repair faulty sensors, or perform system regeneration to restore normal operation.
Trucks manufactured after July 20, 2026, will have the updated software installed at the factory. For trucks built after 2018, the updates will be available at Kenworth and Peterbilt dealerships. All vehicles powered by MX engines remain subject to EPA emissions requirements. Owners must service emissions components to maintain compliance.
The announcement was reported on July 8, 2026. Further details on the rollout timeline or specific customer impact were not provided in the source material.
