Diesel Particulate Filter — Ash Accumulation
The DURAMAX-P242F (Duramax) diesel fault code means: Diesel Particulate Filter — Ash Accumulation. This is a serious severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- Yes, with caution
- DIY difficulty
- intermediate
- Estimated cost
- $2,000-$3,500
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View pilot availability →What Are the Symptoms of DURAMAX-P242F?
- Reduced engine power / limp mode
- Check Engine Light
- Poor throttle response
- Possible DPF regen occurring more often (if DPF-related)
What Causes DURAMAX-P242F? (Most Likely First)
- DPF ash loading at end of service life Very Likely
- Carbon / soot accumulation in EGR system (chronic Duramax issue) Likely
- Damaged EGR cooler — coolant leak into intake (LLY) Possible
- Wiring or connector fault to sensor/actuator Possible
Can I Still Drive with DURAMAX-P242F?
Yes, with caution. DURAMAX-P242F is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What is P242F on a Duramax?
Duramax code P242F (Diesel Particulate Filter — Ash Accumulation) is a serious-severity diagnostic trouble code triggered by the engine control module when it detects a problem in the associated system. Duramax EGR systems carbon up quickly — many owners install an EGR cleaning schedule every 75K miles.
Is a Duramax P242F safe to drive?
Short-term driving is acceptable, but prolonged limp-mode operation indicates the EGR or DPF system needs service to prevent DPF damage.
How much does it cost to fix P242F on a Duramax?
Typical repair runs $2,000-$3,500 depending on whether the valve can be cleaned or requires replacement.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose DURAMAX-P242F?
Connect scan tool and check EGR commanded vs. actual position in live data
Command EGR open/closed with bidirectional scanner and verify smooth operation
Remove EGR valve and visually inspect for carbon packing — clean or replace as needed
If EGR cooler is suspect, pressure test for internal leaks (coolant getting into intake)
After cleaning, clear code and monitor for return — if returns, consider a replacement EGR valve
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines P242F as a generic OBD-II code)
P242F on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
Which Vehicles Commonly Get DURAMAX-P242F?
- 2007.5-2010 Chevy Silverado 2500/3500 HD 6.6L Duramax LMM
- 2007.5-2010 GMC Sierra 2500/3500 HD 6.6L Duramax LMM
- 2011-2016 Chevy Silverado 2500/3500 HD 6.6L Duramax LML
- 2011-2016 GMC Sierra 2500/3500 HD 6.6L Duramax LML
- 2017+ Chevy Silverado 2500/3500 HD 6.6L Duramax L5P
- 2017+ GMC Sierra 2500/3500 HD 6.6L Duramax L5P
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