OBD-II · Engine and powertrain (P)
P242F
DPF restriction - ash accumulation bank 1
What it means
The engine computer estimates that the DPF is loaded with ash. Ash is the unburnable residue from engine oil; regeneration cannot remove it, only professional cleaning or a new filter.
Symptoms
- engine warning light and/or DPF warning
- reduced power (limp mode)
- more frequent regenerations (fan running after switch-off, higher idle)
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | high mileage ash build-up (normal wear of the DPF) |
| 02 | engine oil that is not low-ash (not the specified ACEA C / low-SAPS grade) |
| 03 | engine burning oil (turbo seals, valve stem seals, worn rings) |
| 04 | ash counter not reset after a DPF was cleaned or replaced |
| 05 | faulty pressure sensor or hoses giving a false reading |
What to check, step by step
- 01Read the ash load / ash mass value and DPF history with a diagnostic tool.
- 02Check pressure sensor hoses and sensor readings (engine off should be near zero).
- 03Check that the correct low-SAPS oil is being used and whether the engine uses oil.
- 04If ash really is high, have the DPF professionally cleaned or replaced.
- 05After cleaning or replacement, reset the ash/DPF adaptation values with the diagnostic tool.