Did You Hear the News? Cummins and PACCAR Have Announced Software Changes to Their Diesel Engines
If you’ve ever experienced a DEF-related derate, you know how frustrating (and costly) it can be. A faulty sensor or emissions system issue could force your truck into a severe speed restriction, sometimes limiting you to just 5 mph until repairs were made.
Now, there’s good news for truck owners and fleet managers.
Cummins and PACCAR have announced new software updates for eligible diesel engines that are designed to reduce unnecessary downtime while still meeting EPA emissions requirements. Thanks to updated guidance from the Environmental Protection Agency (EPA), these software changes give drivers significantly more time to address certain DEF-related issues before the truck reaches its most restrictive operating mode.
So, What's Changing?
For eligible Cummins engines and PACCAR MX-11 and MX-13 engines:
- The final derate speed increases from 5 mph to 25 mph.
- Drivers now have up to 160 hours – instead of just 4 hours – to address certain DEF quality or component-related issues before reaching the final derate stage.
- Trucks manufactured after July 20, 2026, will receive the updated software from the factory, while many trucks built after 2018 can receive the update through authorized dealers.
Why This Matters
These updates are a big win for owner-operators and fleets because they help reduce unnecessary downtime caused by DEF system faults. Instead of immediately being sidelined by a severe derate, drivers have more flexibility to safely finish a trip or get to a repair facility.
This means:
- Less roadside downtime
- Fewer expensive tows
- Reduced delivery delays
- More time to schedule repairs
- Increased productivity for your fleet
Don't Ignore DEF Issues
While these software updates provide more flexibility, they do not eliminate the need to repair your emissions system. DEF systems are still required to operate properly, and trucks must remain compliant with federal emissions regulations. The updates simply prevent certain faults from immediately putting your truck into an extreme limp mode
What Should You Do?
If your truck is equipped with a Cummins engine or a PACCAR MX-11 or MX-13 engine built after 2018, you may qualify for the updated software.
It’s a simple update that could save you hours of downtime the next time a DEF-related issue occurs.
Call Houpert today at (856) 767-2828 to schedule your update!
Article Credit: “Cummins, PACCAR Ease DEF Derates After EPA Guidance” by Heavy Duty Trucking.