Fuel Volume Regulator Control Circuit High
The fuel volume regulator control circuit is receiving too much electrical voltage, like a water valve stuck in the fully-open position. This prevents the ECU from properly controlling fuel pressure to the engine.
The ECM monitors the control voltage sent to the fuel volume regulator solenoid. When voltage remains higher than expected for an extended period, the ECU detects a circuit malfunction. The regulator should respond to variable voltage commands to adjust fuel pressure dynamically.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Regulator Control Voltage | 0.5-4.5 volts (variable) | Continuously above 4.8 volts |
| Circuit Resistance | 4-12 ohms | Below 2 ohms (short condition) |
Code P0004 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0004 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.