Paccar Launches Software Update in Response to EPA Revised DEF Inducement Guidance
Paccar will initiate software updates for trucks equipped with MX-11 and MX-13 engines in response to the U.S. Environmental Protection Agency's (EPA) revised diesel exhaust fluid (DEF) inducement guidance. The new software will raise the final inducement speed limit and extend the time for drivers to address emissions issues, reducing operational disruptions.
News Summary
- Paccar announced it will begin software updates for trucks equipped with MX-11 and MX-13 engines following the EPA's revised guidance on diesel exhaust fluid (DEF) inducement.
- Trucks produced after July 20, 2026 will come preloaded with the new software, while vehicles built after 2018 can be updated at Kenworth and Peterbilt dealerships.
- The new software aims to improve reliability and reduce operational disruptions by raising the final inducement speed limit and giving drivers more time to address emissions-related issues.
In-Depth Analysis
Paccar is the second major manufacturer to roll out software upgrades since the EPA updated its guidance in March 2026. The guidance allows manufacturers to adopt alternative monitoring technologies, including software-based methods. The EPA stated the revisions aim to improve system reliability while maintaining emissions compliance.
Under the updated guidance, Paccar's software raises the final inducement speed limit from 5 miles per hour to 25 miles per hour. The time drivers have to address component or DEF quality issues is also extended from 5 hours to 160 hours before reaching the final inducement speed limit.
Previously, Daimler Truck North America announced plans in June 2026 to update approximately 330,000 in-use trucks. Newly produced Freightliner and Western Star vehicles already come preloaded with the updated software.
Although the EPA's recent guidance is expected to provide relief for trucking and agricultural businesses that have reported issues with DEF sensor equipment failures, the agency last week also proposed a rule to amend parts of its 2023 heavy-duty diesel nitrogen oxide regulations, including eliminating DEF-related engine derates and speed limiters on new trucks.
Despite this, industry groups including the American Trucking Associations (ATA) welcomed any regulatory relief earlier this year.
"The EPA's decision to give manufacturers the flexibility to pause these inducements and completely eliminate problematic sensors by monitoring actual truck emissions is a pragmatic solution that reflects how these systems perform in the real world," said Patrick Kelly, ATA's vice president of environmental affairs, in a statement in March 2026.