P0004Powertrain
Powertrain · SAE
Fuel Volume Regulator Control Circuit High
Meaning
The command signal to the fuel volume control valve exceeds the maximum expected limit. The ECM detects an excessive control voltage, typically caused by a short to supply voltage.
Common causes
- Short to supply voltage in the FCV command wiring
- FCV valve winding shorted to positive
- ECM output driver failure (signal stuck high)
- Loss of control circuit ground
- Damaged connector with accidental bridging
Symptoms
- Check-engine light on
- Excessive or unregulated high rail pressure
- Erratic performance and smoke
- Rail pressure relief valve may open
- Limp-home mode or protective shutdown
Severity
High: overpressure in the common rail can cause structural damage to injectors and pump; stop and repair.
What to do
- Measure voltage at the FCV command pin; a value near battery voltage indicates a short to supply
- Check command wiring insulation against supply voltage
- Measure FCV coil resistance
- Inspect connector for bridging or damage
- Check ECM output driver if wiring is intact