Fuel Volume Regulator Control Circuit High
The P0004 code indicates that the Engine Control Module (ECM) has detected a high voltage or resistance in the fuel volume regulator control circuit. This regulator controls fuel pressure by adjusting the amount of fuel returning to the tank. A high circuit condition typically means the voltage signal from the regulator or its wiring is above the expected range, often due to a short to power, open circuit, or faulty component. This can lead to incorrect fuel pressure, affecting engine performance and fuel economy.
1. Most Common Causes
- Short to battery voltage (B+) in the fuel volume regulator control circuit wiring
- Open circuit or excessive resistance on the ground side of the regulator circuit
- Faulty or internally damaged fuel volume regulator (quantity control valve / M-PROP on diesel systems)
- Corroded, damaged, or moisture-contaminated connector or pin at the fuel volume regulator
- Internal ECM/PCM failure (less common, but possible)
- Harness wiring damaged by chafing, heat, or rodents
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor engine performance (hesitation, stalling)
- Decreased fuel economy
- Hard starting or rough idle
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data to confirm P0004.
Step 2: Visually inspect the fuel volume regulator connector and wiring for damage, corrosion, or loose connections.
Step 3: Use a multimeter to check the regulator control circuit for voltage and resistance; compare to manufacturer specs.
Step 4: Test the fuel volume regulator itself by measuring its resistance and actuation; replace if out of spec.
Step 5: If wiring and regulator are good, check ECM for faults; reprogram or replace if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as incorrect fuel pressure can cause engine damage or stalling. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the cause. Replacing the fuel volume regulator may cost $100-$200 including parts and labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.