P009EFuel Pressure Relief Control Performance/Stuck Off
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- The fuel pressure relief control is an electrically controlled valve on the fuel rail that the engine control module opens to reduce rail pressure deliberately, for example on overrun, on load drops or when the engine is switched off. It differs from the purely mechanical pressure relief valve, which opens passively at overpressure, and from the pressure regulator, which controls pressure continuously. Manufacturer documents show this code mainly on heavy-duty diesel engines. P009E means that rail pressure does not drop as expected when the valve is commanded open, i.e. the valve does not open or opens too little. On some trucks the manufacturer has corrected false detections by a software update, so other fuel codes and real symptoms should be checked first.
- What you may notice
- Check engine light on
- Reduced power possible
- Sometimes no further symptoms
- Likely causes
- PossibleFalse detection by engine control software (updates exist for some trucks)
- PossibleValve sticking closed, e.g. from contamination
- RareRail pressure sensor inaccurate
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.