[Stay on top of transportation news: Get TTNews in your inbox.]
Mack, VTNA lay out DEF derate software update schedules
OEMs to offer post-2010 model-year updates by end of 2027
Mack launched a revamp of the Anthem in June 2025. (Mack Trucks)
Key Takeaways:
- Volvo Trucks North America and Mack Trucks said July 27 they began incorporating revised EPA DEF inducement software in new trucks produced since May.
- The updates raise the final speed limit to 25 mph from 5 mph and extend inducement timing, following EPA guidance issued in August 2025.
- Mack and VTNA plan updates for model-year 2024 and newer vehicles by summer’s end, expanding to eligible post-2010 models by 2027.
Volvo Group divisions Mack Trucks and Volvo Trucks North America became the latest original equipment manufacturers on July 27 to lay out plans for software updates incorporating revised diesel exhaust fluid inducement parameters.
The updates follow revised guidance from the Environmental Protection Agency in August 2025. EPA issued the guidance to offer carriers and farmers greater flexibility and uptime.
Under the revised guidance, the speed limit in the final inducement will increase to 25 mph from 5 mph, and the time to reach final inducement for component-related issues will be extended.
Each Volvo Group unit said its flagship on-highway tractors began rolling off production lines in May with the updates already in place.
VTNA began producing D13 VGT and D13 TC engines with the updated software for the revamped VNL and VNR trucks in May, the company said. The OEM overhauled the VNL in January 2024 and the VNR in March 2025.
Similarly, Mack started equipping the Pioneer and Anthem models with MP 13 engines with the update in May. Mack unveiled the Pioneer as its new flagship on-highway tractor in April 2025 and launched a revamp of the Anthem in June 2025.
Mack and VTNA plan to roll out software updates to model-year 2024 and newer vehicles by the end of the summer. The update will then be available to all post-2014 model-year vehicles by the second quarter of 2027 and all eligible post-2010 model-year vehicles by the end of 2027.
The first truck or engine maker to provide details of its software update plans was Daimler Truck North America.
Image
The AI Summit at TMC
The Technology & Maintenance Council and Transport Topics will co-host a new event at TMC’s 2026 Fall Meeting, Sept. 20-24, to advance the conversation about artificial intelligence implementation in the trucking industry. Read more
DTNA said June 22 that it began rolling out the update in February for about 330,000 in-service vehicles with DD15 engines (model-years 2021-2025) and DD13 engines (model-years 2022-2025).
Updates for Freightliner and Western Star trucks are set to continue throughout 2026. Freightliner and Western Star vehicles equipped with Detroit engines are already shipping with the updated software.
A couple of weeks after DTNA’s announcement, Paccar and Cummins said they had begun rolling out the updates that lift the minimum speed for trucks before DEF tanks must be refilled or sensors repaired.
Cummins is offering updates for more than 1.5 million engines in medium- and heavy-duty trucks, including certain trucks dating to model-year 2017, the company said July 6.
Kenworth and Peterbilt parent company Paccar will offer updated software for vehicles equipped 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 obtain the updates at Peterbilt and Kenworth dealerships.
Selective catalytic reduction technology uses DEF to convert nitrogen oxides into nitrogen and water, supporting compliance with EPA emissions standards.
Brad Gulick of Eaton Mobile Power Group discusses hydraulic systems that power trucks. He addresses dump pump sizing and more. Tune in above or by going to RoadSigns.ttnews.com.
Inducements are built-in safeguards on trucks and tractors that ensure emissions systems function appropriately by cutting vehicle speed and power if issues are detected.
SCR technology, and therefore the need for DEF, was introduced to meet 2010 model-year EPA mandates. DEF is a nontoxic, colorless and odorless solution comprising 32.5% urea and 67.5% deionized water.
Engines will still require DEF. The slowdown “induces” the driver to correct the issue, typically by refilling the DEF tank, repairing a faulty sensor or component, or performing a regeneration cycle.
However, the EPA has also proposed ending DEF-related engine derates, replacing the gradual dialing back of truck performance with visual or audible notifications.
A surprise inclusion in a long-awaited notice of proposed rulemaking on changes to NOx tailpipe emissions regulations, axing DEF derates is the latest step in the Trump administration’s ongoing rollback of Biden-era emissions regulations.
