P3655high severityPowertrain
GDI Fuel Metering Unit Control Stuck
on 2014 Audi R8 5.2L V10 · AWD
What this code means
The high-pressure fuel pump metering unit that controls fuel volume entering the pump is stuck, causing incorrect fuel rail pressure.
Symptoms
- Check Engine Light
- Fuel pressure too high or too low
- Engine stalling
- Hard starting
- Rough running
- Fuel smell from engine
Common causes
- Metering unit solenoid failure
- Contaminated fuel blocking metering valve
- Metering unit wiring short
- Mechanical debris in metering valve
- PCM driver circuit failure
Diagnostic steps
- Monitor fuel metering command vs actual rail pressure
- Test metering unit solenoid resistance
- Inspect fuel quality
- Command metering unit through range with scan tool
- Check PCM driver output
Repair notes
Replace high-pressure fuel pump metering unit. May require full pump replacement depending on design. Check fuel quality.
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