P0001
Fuel Volume Regulator A Control Circuit/Open
The ECU detects an open circuit in the control of fuel volume regulator A (often the metering valve on the high-pressure fuel pump). The actuator does not respond, so rail pressure cannot be controlled accurately.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Wiring break or unplugged connectorCommon
- Regulator solenoid coil openPossible
- ECU output driver failedLess likely
Parts involved
- Fuel Volume Regulator
- High Pressure Fuel Pump
- FVR Wiring
- FVR Connector
P0001 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.