P1189high severityPowertrain
Fuel Rail Pressure Deviation
on 2002 BMW M5 4.9L V8 S62 · RWD
What this code means
The DME detected that the actual fuel rail pressure deviates significantly from the commanded fuel rail pressure. The high-pressure fuel system is not maintaining the target pressure requested by the DME.
Symptoms
- Check Engine Light
- Loss of power
- Engine hesitation
- Hard starting
- Rough running at various RPMs
Common causes
- Failing high-pressure fuel pump
- Clogged fuel filter
- Leaking fuel injectors
- Fuel pressure regulator failure
- Low-pressure fuel pump weak
Diagnostic steps
- Monitor commanded vs actual fuel rail pressure with scan tool
- Test low-pressure fuel pump output
- Inspect fuel filter condition
- Check for fuel injector leaks
- Test high-pressure pump output
Repair notes
Replace the failing fuel system component causing the pressure deviation.
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