Engine and gearbox (P)
P0001: Fuel Volume Regulator A Circuit Open
The engine control unit (ECU) has detected an open circuit in the control of the fuel volume regulator A. This often involves the metering valve on the high-pressure fuel pump, affecting the ability to control rail pressure accurately.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Engine may not start
- Reduced engine performance
- Check engine light on
- Possible fuel odour
Common causes
- Wiring break or unplugged connector
- Regulator solenoid coil open
- ECU output driver failed
How to check it yourself
- Inspect wiring and connectors for damage or disconnection
- Test the regulator solenoid coil for continuity
- Check ECU for faults
Can I keep driving?
Do not drive the car if there is a fuel smell or the engine is not running properly.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer