Cummins, Paccar Ease DEF Derates After EPA Guidance
The engine makers are rolling out software updates that give truck operators more time to address DEF and SCR faults while keeping EPA emissions requirements in place.
Software Updates Target DEF Derates
Cummins and Paccar are rolling out diesel engine software updates after revised EPA guidance on diesel exhaust fluid inducements. The changes are meant to give truck operators more time to correct DEF and selective catalytic reduction issues before a truck reaches its most severe speed or power limitation.
DEF inducements, often called derates, are built into emissions systems to push drivers and fleets to address low DEF levels, sensor problems, or SCR performance issues. The systems remain part of EPA compliance, but the new calibrations give operators a wider operating window when faults appear.
More Time Before Final Inducement
Transport Topics reported that the revised guidance raises the final inducement speed to 25 mph from 5 mph and extends the time before that final stage for component-related problems. Cummins said updates are available for more than 1.5 million medium- and heavy-duty engines, with rollout timing varying by engine platform and model year.
Paccar said updated software will be available for vehicles with MX-11 and MX-13 engines. Trucks built after July 20 will receive the software at the factory, while eligible Peterbilt and Kenworth trucks built after 2018 can get updates through dealers.
Compliance Still Applies
The updates do not remove DEF requirements. Fleets still need to repair emissions components and keep SCR systems operating properly. The practical change is uptime: trucks with certain DEF-related faults should have more room to reach service instead of being forced into a severe derate immediately.
