Paccar updates MX-11 and MX-13 engine software

Updated software for vehicles equipped with the Paccar MX-11 and MX-13 (shown) will reflect revised EPA guidance on DEF inducements. (Photo: Paccar)

Paccar Inc. announced that Peterbilt Motors Company and Kenworth Truck Company will implement updated software for vehicles equipped with Paccar MX-11 and MX-13 engines, reflecting revised U.S. Environmental Protection Agency’s (EPA) guidance on diesel exhaust fluid (DEF) inducements.

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 (SCR) system performance. DEF inducements prompt drivers to correct the issue by refilling the DEF tank, repairing faulty sensors or performing a system regeneration.

In alignment with the revised guidance, updates to the MX-11 and MX-13 engines will increase the final inducement speed limit from 5 mph to 25 mph; and extend the timeline from four to 160 hours for component-related or fluid-quality issues before reaching final inducement speed limit. Trucks manufactured after July 20, 2026, will have the software installed at the factory. Trucks built after 2018 will be available for these software updates at Peterbilt and Kenworth dealerships.

All MX-powered vehicles remain subject to EPA emissions requirements, the company advised. Vehicles requiring repairs to emissions components must be serviced to maintain compliance.