P0002
Fuel Volume Regulator A Control Circuit Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- 02
- FaultThe specific fault in that area
What it means
P0002 is the generic code for a performance problem in the fuel volume regulator 'A' control circuit. The engine control unit commands the regulator to meter fuel to the high pressure pump, but the electrical control or the resulting fuel pressure does not match what it expects. It is mainly seen on direct injection and some common rail systems, and the exact regulator layout depends on the engine.
Symptoms
- Engine management light on
- Hesitation or poor acceleration
- Hard starting or long cranking
- Rough idle or occasional stalling
- Reduced power or limp mode
- Surging at steady speed
Possible causes
- Faulty or sticking fuel volume regulator (metering valve)likely
- Damaged wiring, poor connector contact or corrosion in the regulator control circuitlikely
- Low fuel supply pressure from a weak lift pump, blocked fuel filter or restricted pickuppossible
- Worn or failing high pressure fuel pumppossible
- Faulty fuel rail pressure sensor giving inaccurate readingspossible
- Contaminated or poor quality fuel affecting regulator or pump operationrare
- Fault within the engine control unit driver circuitrare
How to diagnose
- Read freeze frame data and note engine speed, load, temperature and fuel pressure when the code set, then check for other stored fuel pressure codes.
- Visually inspect the regulator wiring and connector for chafing, heat damage, water ingress, corrosion or loose pins.
- Check the fuel level and fuel quality, and check the fuel filter service history.
- Compare commanded and actual fuel rail pressure on live data at idle and under load.
- Check low pressure fuel supply pressure and volume against the manufacturer's specification.
- Test the regulator for correct resistance and check its control signal, power and ground with a multimeter or oscilloscope, following the model-specific procedure.
- Compare the rail pressure sensor reading with a known good reference and check its wiring and supply.
- Check the high pressure pump only after the supply, wiring and regulator checks are clear, using the manufacturer's procedure.
How to fix
- Repair or replace damaged wiring and clean or renew faulty connectors.
- Replace the fuel volume regulator if it is sticking or out of specification, where it is serviced separately on that engine.
- Replace the fuel filter and repair any low pressure supply fault such as a weak lift pump or blocked pickup.
- Replace the high pressure fuel pump if testing confirms it cannot build correct pressure.
- Replace a faulty fuel rail pressure sensor.
- Drain and replace contaminated fuel, then clear the code and confirm it does not return.
Can I keep driving?
The car may drive with reduced power, but fuel pressure faults can cause stalling and may damage the high pressure pump if ignored. Have it checked soon and avoid long journeys or overtaking until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.