OBD-II · Engine and powertrain (P)
P2002
DPF efficiency below threshold bank 1
What it means
The engine computer has detected particulate-filter efficiency below the required threshold on bank 1. Depending on the vehicle, it evaluates pressure behaviour, a downstream particulate sensor or other monitoring data; the code alone does not identify a failed filter.
Symptoms
- engine warning light
- sometimes a DPF warning light or reduced power (limp mode)
- possibly black soot at the tailpipe if the filter is cracked
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | split, disconnected or blocked DPF pressure sensor hoses |
| 02 | faulty DPF differential pressure sensor |
| 03 | cracked or melted DPF substrate |
| 04 | exhaust leak before the DPF |
| 05 | DPF removed or hollowed out (illegal for road use in most of Europe) |
| 06 | on some cars also set with a heavily soot-loaded DPF |
What to check, step by step
- 01Read live data: DPF differential pressure at idle and at 2,500-3,000 rpm, plus calculated soot load.
- 02Inspect both pressure hoses from the sensor to the exhaust for splits, melting, blockage or being swapped.
- 03Check for exhaust leaks between the engine and the DPF.
- 04With the exhaust cool, inspect for fresh soot downstream of the DPF. This suggests impaired filtration; confirm filter integrity and the OEM monitor results before replacement.
- 05Test or replace the pressure sensor if readings are implausible with the engine off (should read close to zero).
- 06Only then condemn the DPF itself.