Mack Trucks is extending updated diesel exhaust fluid (DEF) inducement software to vehicles built as far back as the 2010 model year, following revised guidance from the US Environmental Protection Agency (EPA). The DEF inducement software raises the final derate speed from 5mph to 25mph and extends the repair window from four hours to 160.

The change matters more to fleets than a software rollout suggests. A truck that drops to 5mph is effectively stranded wherever the fault occurs, while one that can still manage 25mph can usually reach a dealer or a yard under its own power.

The repair window is the larger shift. Moving from four hours to 160 gives operators close to a working week to source parts and book workshop time, rather than facing an almost immediate derate on a fault that may carry no measurable emissions penalty.

Mack began fitting the software in May 2026 on Pioneer and Anthem models with MP13 engines, and expects to cover all 2024 and newer vehicles by the end of summer. Post-2014 vehicles follow by the second quarter of 2027, with remaining eligible post-2010 trucks served through dealers by the end of that year.

Jonathan Randall, President of Mack Trucks North America, said in a statement that the rollout gives new vehicles the capability while setting a clear path for legacy updates. The staged timeline reflects the split between trucks with remote update capability and older units that must visit a dealer.

Source: Mack