P242F: Diesel Particulate Filter Restriction - Ash Accumulation
The DPF is filling with ash, which doesn't burn off during regeneration. It needs to be cleaned or replaced.
Green, yellow, red: three ways P242F can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
Light on, drives fine, high mileage. Plan DPF cleaning.
Schedule a repair
Power loss or regens getting frequent. Schedule DPF cleaning or replacement.
Stop and get help
Severe derate. Stop and get help.
Symptoms you might notice
- DPF light
- Power loss
- Frequent regens
Common causes, cheapest first
- Normal ash buildup at high mileage
- Engine burning oil (more ash)
- Wrong engine oil (high ash)
What you can check before calling
- Use the low-ash diesel oil spec your manual calls for
- Note any oil consumption
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Want the full story? Read our guide: DPF regeneration explained: passive, active and forced.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
More diesel & cummins codes
- P2002
Diesel Particulate Filter Efficiency Below Threshold (Bank 1) - P2459
Diesel Particulate Filter Regeneration Frequency - P2453
Diesel Particulate Filter Pressure Sensor A Circuit Range/Performance - P2454
Diesel Particulate Filter Pressure Sensor A Circuit Low - P2455
Diesel Particulate Filter Pressure Sensor A Circuit High - P244A
Diesel Particulate Filter Differential Pressure Too Low
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P242F mean?
P242F means "Diesel Particulate Filter Restriction - Ash Accumulation". The DPF is filling with ash, which doesn't burn off during regeneration. It needs to be cleaned or replaced.
Can I drive with code P242F?
It depends on what the vehicle is doing. Green: Light on, drives fine, high mileage. Plan DPF cleaning. Yellow: Power loss or regens getting frequent. Schedule DPF cleaning or replacement. Red: Severe derate. Stop and get help.
What causes P242F?
The most common causes are: normal ash buildup at high mileage; engine burning oil (more ash); wrong engine oil (high ash).
Is P242F a serious code?
It can be. Severe derate. Stop and get help.
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