P3658moderate severityPowertrain
GDI Fuel Rail Pressure Oscillation Detected
on 2017 Audi A6 3.0L Supercharged V6 · FWD
What this code means
The fuel rail pressure in the GDI system is oscillating beyond normal limits, indicating a control instability or mechanical issue in the high-pressure fuel system.
Symptoms
- Check Engine Light
- Engine vibration at idle
- Fuel injector noise louder than normal
- Idle quality degradation
- Possible misfire symptoms
- Fuel smell intermittent
Common causes
- HP fuel pump volume control valve hunting
- Fuel rail pressure sensor noise
- Pressure damper failure in fuel rail
- Fuel injector leak causing pressure drops
- HP pump cam follower uneven wear
Diagnostic steps
- Monitor fuel rail pressure waveform with fast data rate
- Check HP pump volume control solenoid
- Inspect pressure damper in fuel rail
- Test fuel injectors for leak-back
- Inspect HP pump cam follower for uneven wear
Repair notes
Replace pressure damper if failed. Service volume control solenoid. Replace cam follower if showing uneven wear.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1