Short answer
To meet the 2010 emissions rules, Navistar first pursued an EGR-only approach on its MaxxForce engines instead of SCR with DEF. Trade press reports that the strategy ran into durability and regulatory trouble, and Navistar moved to SCR and to Cummins engines in some models. Owners of these engines should expect EGR-related service to be a big part of their maintenance.
Safety first. Diesel injection systems run at extremely high pressure; a pinhole leak can inject fuel through skin. Exhaust and turbo parts stay very hot long after shutdown. Never open a hot cooling system. If you are unsure, stop and see a qualified diesel technician.
Start with the easy checks
- Check for open campaigns or updates with an International dealer.
- Keep records of EGR, cooler and turbo work.
- Watch coolant level.
Likely causes, most common first
- EGR cooler and valve problems
- Commonly reported.
- Soot loading
- Affects turbo and DPF.
These are common causes, not a diagnosis. The same symptom can have a different cause on your engine; codes, tests and your service information decide.
When to stop and see a diesel tech
- Coolant loss or EGR codes.
- Any heavy-duty engine work.
Questions
Did Navistar switch to SCR?
Yes. Trade press reports Navistar abandoned its EGR-only approach in 2012 and adopted SCR.
Related symptoms
Emissions
Can a clogged EGR valve cause rough running and low power?
Troubleshoot →CoolingMy diesel is losing coolant with no visible leak. Why?
Troubleshoot →EmissionsWhy does my diesel say DEF fault or "speed limited"?
Troubleshoot →Where this comes from
- Truck News: How Navistar solved its EGR problems
- Truck News: Navistar puts emissions debacle in the rearview mirror
Last reviewed 2026-10-19. General information only: confirm with your service information and a qualified diesel technician.