Common DPF faults and what they can mean.
Fault codes point us in the right direction, but they rarely tell the whole story. Live data and physical checks are still needed.
| Symptom or code area | Possible cause | What we normally check |
|---|---|---|
| DPF warning light | Soot loading, failed regeneration, pressure fault or upstream engine issue. | Fault codes, soot value, ash value, temperature data and regen status. |
| Limp mode | High back pressure, boost fault, sensor issue or engine protection mode. | Pressure readings, turbo control, EGR operation and live data plausibility. |
| Pressure sensor fault | Failed sensor, split hose, blocked pipe, wiring fault or actual high pressure. | Differential pressure at idle and revs, pipe condition and sensor supply/ground. |
| Failed regeneration | Temperature too low, driving conditions, engine fault or soot load too high. | Temperature sensors, thermostat, fuel level, engine codes and regen permissions. |
| Filter cleaned, fault returned | Root cause still present or filter no longer serviceable. | Previous work history, pressure readings, ash loading and upstream faults. |