Fuel and air

P0004 — Fuel Volume Regulator Control Circuit High

Severity: medium Drive with care, to a shop

What P0004 means

P0004 means the PCM detected abnormally high voltage in the fuel volume regulator control circuit. This valve meters how much fuel goes to the high-pressure pump, which sets rail pressure. A short to voltage, an open circuit, a failing regulator or a bad driver inside the PCM can make it lose control of fuel delivery.

Symptoms

  • Check engine light on
  • Reduced power or limp mode
  • Rough or uneven idle
  • Higher fuel consumption
  • Engine may stall
  • Hard starting or long cranking

Possible causes

  1. Failed fuel volume regulator solenoid
  2. Damaged wiring harness or poor connector contact
  3. Open circuit or short to voltage in the regulator wiring
  4. Faulty driver circuit in the PCM
  5. Fuel pressure sensor or related component fault

How to diagnose

  1. Scan for codes and freeze frame data, and note any other fuel system codes
  2. Inspect the regulator connector and harness for chafing, corrosion, heat damage or a loose fit
  3. Compare commanded and actual rail pressure at cranking, idle and under load
  4. Check low-pressure supply: lift pump pressure and volume, and fuel filter condition
  5. Measure the regulator solenoid resistance against specification
  6. Test the regulator wiring for opens and shorts to voltage and ground, and verify power supply
  7. Command the regulator with a scan tool if supported and watch the response
  8. If wiring and regulator are good, verify the PCM driver before replacing the module

Common fixes

  • Replace the fuel volume regulator solenoid
  • Repair or replace damaged wiring and connectors
  • Replace or reprogram the PCM if its driver is confirmed faulty
  • Fix low-pressure supply problems such as a clogged filter or weak lift pump
  • Replace the fuel pressure sensor if it is defective

Questions and answers

What does P0004 mean?

It indicates a high signal in the fuel volume regulator control circuit. The regulator or its wiring is the usual culprit, and the PCM is less common.

Can I drive with P0004?

Only a short distance to a shop. The engine may lose power or stall, so don't put off the repair.

How do I fix P0004?

Start with the regulator wiring and connector, then test the regulator and fuel pressure. Consider replacing the PCM last.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.