OBD-II · Engine and powertrain (P)
P0093
Fuel system leak detected - large leak
What it means
The engine computer detects a fuel-pressure or delivery discrepancy consistent with a large leak. This can be external fuel leakage, excessive internal return leakage or a supply/control fault; an external leak is not proven by the code. Stop safely and switch off until a dangerous leak has been excluded.
Symptoms
- smell of diesel
- visible fuel leak or wet engine
- loss of power, engine may shut down
- engine warning light
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | external leak at a fuel pipe, union, hose or other fuel-system component |
| 02 | excessive injector return leakage or a leaking rail pressure-relief valve |
| 03 | fuel supply restriction, air ingress or inadequate pump delivery |
| 04 | faulty metering or pressure-control valve |
| 05 | rail-pressure sensor or wiring fault |
What to check, step by step
- 01Stop safely and switch off the engine. If fuel is visible or strongly smelled, do not restart; arrange recovery.
- 02Do not touch suspected leak points or loosen high-pressure connections. Have a workshop inspect the system after pressure has decayed according to the OEM procedure.
- 03If external leakage is excluded, check fuel supply and filter condition, pressure-control operation and rail-sensor plausibility.
- 04Have a workshop perform the approved injector return-flow and relief-valve tests using suitable equipment.
- 05Repair the confirmed fault and replace single-use high-pressure pipes as specified; verify leak-tightness using the OEM procedure.