July 27, 2026, 2:56 p.m., EDT
Mack launched a rework of the Anthem in June 2025. (Mack Trucks)
Table of Contents
Key Takeaways:
- Volvo Trucks North America and Mack Trucks announced July 27 that they have begun integrating the revised EPA-DEF incentive software into new trucks manufactured since May.
- The updates increase the final speed limit from 5 mph to 25 mph and extend the timing of incentives under EPA guidelines issued in August 2025.
- Mack and VTNA plan updates for model year 2024 and newer vehicles by the end of the summer and expansion to eligible post-2010 models through 2027.
Volvo Group’s Mack Trucks and Volvo Trucks North America divisions on July 27 became the latest original equipment manufacturers to submit plans for software updates that include revised diesel exhaust fluid discharge parameters.
The updates follow revised guidance from the Environmental Protection Agency in August 2025. EPA issued the guidance to provide more flexibility and uptime for shippers and farmers.
Under the revised guidance, the speed limit in the final notice will be increased from 5 mph to 25 mph and the time to reach the final notice will be extended for component-related issues.
Each Volvo Group unit said its flagship road tractors rolled off the assembly line in May with the updates already installed.
VTNA began producing D13 VGT and D13 TC engines in May with the updated software for the redesigned VNL and VNR trucks, the company said. The OEM revised the VNL in January 2024 and the VNR in March 2025.
Mack also began equipping the Pioneer and Anthem models with MP 13 engines with the May update. Mack introduced the Pioneer as its new flagship on-road tractor in April 2025 and launched a redesign of the Anthem in June 2025.
Mack and VTNA plan to roll out software updates for 2024 model year and newer vehicles by the end of the summer. The update will then be available for all post-2014 model year vehicles by the second quarter of 2027 and for all eligible post-2010 model year vehicles by the end of 2027.
The first truck or engine maker to announce details of its software update plans was Daimler Truck North America.
DTNA said on June 22 that the update began rolling out in February to approximately 330,000 in-service vehicles with DD15 engines (2021-2025 model years) and DD13 engines (2022-2025 model years).
Updates for Freightliner and Western Star trucks are scheduled to continue throughout 2026. Freightliner and Western Star vehicles with Detroit engines are already shipping with the updated software.
A few weeks after DTNA’s announcement, Paccar and Cummins said they had begun rolling out the updates, which raise the minimum speed for trucks before DEF tanks need to be refilled or sensors repaired.
Cummins is offering updates for more than 1.5 million engines in medium- and heavy-duty trucks, including certain 2017 model year trucks, the company said July 6.
Kenworth and Peterbilt parent company Paccar will offer updated software for vehicles with MX-11 and MX-13 engines, it said July 6.
Trucks manufactured after July 20 will have the software installed at the factory, the parent company said. Trucks built after 2018 can receive the updates at Peterbilt and Kenworth dealers.
Selective catalytic reduction technology uses DEF to convert nitrogen oxides into nitrogen and water, helping to meet EPA emissions standards.
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Incentives are built-in protections in trucks and tractors that ensure emissions systems are functioning properly by reducing vehicle speed and power when problems are detected.
SCR technology, and therefore the need for DEF, was introduced to meet EPA requirements for the 2010 model year. DEF is a non-toxic, colorless and odorless solution consisting of 32.5% urea and 67.5% deionized water.
Engines still require DEF. The slowdown “causes” the driver to correct the problem, typically by refilling the DEF tank, repairing a faulty sensor or component, or performing a regeneration cycle.
However, EPA has also proposed ending DEF-related engine throttling and replacing gradual reductions in truck power with visual or audible notifications.
The elimination of DEF reductions is a surprise inclusion in a long-awaited notice of proposed rulemaking on changes to NOx emissions standards and the latest step in the Trump administration’s ongoing rollback of Biden-era emissions rules.
https://www.ttnews.com/articles/mack-vtna-def-updates-2026
