GREENSBORO, N.C. — Volvo Trucks North America and Mack Trucks have officially rolled out revised diesel exhaust fluid (DEF) inducement software designed to prevent heavy-duty trucks from entering immediate limp mode when emissions sensors trigger a fault. This move, active as of September 2026, provides operators with a significantly longer window to reach a repair facility before the engine’s electronic control unit triggers speed restrictions or aggressive power derates.

Emissions system failures have long been a primary source of unplanned downtime for the average CDL-A driver. By extending the time allowed for repairs, the manufacturers hope to minimize the frequency of trucks being stranded on highway shoulders due to minor sensor glitches or DEF quality issues. This policy shift aligns with ongoing discussions regarding federal oversight, as the EPA considers broader changes to how emissions-related performance restrictions are managed on heavy-duty diesel engines.

Volvo confirmed that since May 2026, all new trucks featuring D13 VGT and D13TC engines have shipped with the updated software. Many units already in service have received the patch via over-the-air updates. Mack Trucks has followed suit for its Anthem and Pinnacle models equipped with MP13 engines. The company expects to have the update pushed to all 2024 and newer models by the end of this summer, with a target to cover all eligible post-2010 equipment by the conclusion of 2027.

What This Means for Drivers

For an owner-operator or a fleet manager, this update acts as a critical buffer against catastrophic schedule delays. Drivers no longer face an immediate speed cut the moment a non-critical DEF fault code appears, which prevents the dangerous situation of navigating heavy traffic at reduced speeds. This software implementation gives professionals the necessary time to safely route their vehicle to a dealership or preferred shop without risking a total engine shutdown on the side of the road. It essentially replaces rigid, binary performance penalties with a more flexible system that prioritizes driver safety and cargo delivery.

Industry Reaction

The decision by Volvo and Mack mirrors similar software adjustments recently implemented by Daimler Truck North America and Paccar. This industry-wide trend is a direct response to the EPA’s June proposal, which seeks to eliminate DEF-related speed restrictions on future heavy-duty vehicles entirely while maintaining strict environmental standards. As trucking companies hiring today look for ways to boost fleet utilization, these manufacturers are clearly banking on software as a bridge toward improved reliability and reduced overhead for their customers.

Key Points

• Volvo has integrated the update into all D13 VGT and D13TC engine builds since May 2026.
• Mack plans to extend the software patch to all eligible post-2010 models by the end of 2027.
• The EPA is currently evaluating a proposal to remove DEF-related engine derates for all newly manufactured heavy-duty trucks.
• Remote software downloads are being utilized to update existing fleets without requiring a trip to the service bay.

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