Mac, VTNA set up DEF DeRate software update schedule

Volvo Group divisions Mack Trucks and Volvo Trucks North America on July 27 became the latest original equipment manufacturers to plan software updates incorporating revised diesel exhaust fluid induction parameters.

The updates follow revised guidance from the Environmental Protection Agency in August 2025. EPA issued guidance to provide carriers and farmers more flexibility and uptime.

Under the revised guidance, the speed limit at the final spur will increase by 5 mph to 25 mph, and the time to reach the final spur for component-related issues will be extended.

Each unit of Volvo Group said its flagship on-highway tractors had already begun rolling off production lines in May with updates.

VTNA began production of D13 VGT and D13 TC engines with updated software for modified VNL and VNR trucks in May, the company said. The OEM upgraded to VNL in January 2024 and VNR in March 2025.

Similarly, Mac began equipping Pioneer and Anthem models with the MP13 engine with the update in May. Mack unveiled the Pioneer as its new flagship on-highway tractor in April 2025 and launched a new version of the Anthem in June 2025.

Mack and VTNA plan to release the software update for model-year 2024 and newer vehicles by the end of the summer. The update will then be available by the second quarter of 2027 for all post-2014 model-year vehicles and by the end of 2027 for all eligible post-2010 model-year vehicles.

The first truck or engine manufacturer to provide details of its software update plans was Daimler Trucks North America.

DTNA said on June 22 that it began rolling out the update in February to approximately 330,000 in-service vehicles with DD15 engines (model-years 2021-2025) and DD13 engines (model-years 2022-2025).

Updates to the Freightliner and Western Star trucks will continue throughout 2026. Freightliner and Western Star vehicles equipped with Detroit engines are already shipping with the updated software.

A few weeks after the DTNA announcement, Packer and Cummins said they began releasing updates that increase the minimum speed for trucks before refilling DEF tanks or repairing sensors.

Cummins is offering updates for more than 1.5 million engines in medium- and heavy-duty trucks, including some model-year 2017 trucks, the company said July 6.

On July 6, it was said that Packer, parent company of Kenworth and Peterbilt, would introduce updated software for vehicles equipped with MX-11 and MX-13 engines.

The parent company said the software will be installed at the factory on trucks manufactured after July 20. Trucks manufactured after 2018 can receive the update 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.

Induction trucks and tractors have built-in safeguards that ensure proper emissions system functioning by reducing vehicle speed and power if problems are detected.

SCR technology, and hence the DEF requirement, was introduced to meet the 2010 model-year EPA mandate. DEF is a non-toxic, colorless and odorless solution consisting of 32.5% urea and 67.5% deionized water.

Engines will still need DEF. The deceleration prompts the driver to correct the problem, usually refilling the DEF tank, repairing a faulty sensor or component, or performing a regeneration cycle.

However, the EPA has also proposed eliminating DEF-related engine derating, replacing sequential dialing of the truck display with visual or audible notifications.

A surprise inclusion in a long-awaited notice of proposed rulemaking on changes to NOx tailpipe emissions rules, eliminating the DEF derivative is the latest step in the ongoing rollback of Biden-era emissions rules by the Trump administration.