P0004 – Fuel Volume Regulator Control Circuit High (OBD2)
P0004 means "Fuel Volume Regulator Control Circuit High". The voltage in the fuel volume regulator / shutoff valve circuit is above the permitted maximum. For most sensors this points to an open signal or ground wire – the signal "floats" up to the reference voltage – or to a short to voltage.
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P0004 quick summary
| Fault code | P0004 |
|---|---|
| Meaning | Fuel Volume Regulator Control Circuit High |
| System | Powertrain (Engine & Transmission) |
| Vehicles | Generic OBD2 |
| Severity | High |
| Can I drive? | Not recommended. The engine may go into limp mode, cut out or fail to restart. |
| Repair cost | €30 – €800 |
How the fuel volume regulator and shutoff valve work
The fuel volume regulator meters how much fuel enters the high-pressure pump, and the fuel shutoff valve stops the fuel supply; these codes cover their control circuits.
On common-rail diesels and many direct-injection engines, a solenoid valve on the high-pressure pump – called volume regulator, metering unit or inlet metering valve – controls how much fuel the pump compresses. The control unit drives it with a pulse-width signal. Some systems also have a fuel shutoff valve that cuts the supply when the engine is switched off or in an emergency.
Codes P0001–P0004 cover the volume regulator's control circuit (open, range/performance, low, high); P0005–P0007 cover the shutoff valve circuit. Electrical faults stop the control unit from controlling rail pressure, which usually results in limp mode or no start.
Besides wiring problems and failed solenoids, the metering valve can stick because of dirt or water in the fuel. Fuel quality and filter maintenance are therefore part of the diagnosis.
On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 16388 (P0004). Both numbers mean the same fault.
Symptoms of P0004
- Check Engine light on
- Limp mode, loss of power
- Hard starting or no start
- Engine cuts out or does not switch off properly (shutoff valve)
- Unstable idle
Most common causes of P0004 (most likely first)
Mechanic's Pro Tip
On many diesels the metering valve can be replaced separately from the high-pressure pump – much cheaper than a complete pump. Check parts availability for your engine before accepting a pump replacement quote.
1.Open circuit in the signal or ground wire
Most likelyA loose ground connection is a very common cause.
2.Signal wire shorted to the 5 V reference or battery voltage
3.Faulty fuel volume regulator / shutoff valve
4.Damaged wiring or connector at the pump
Fuel and heat attack connectors on the high-pressure pump.
5.Dirt or water in the fuel
Contamination makes the metering valve stick.
6.Blown fuse or missing supply
Check the supply to the valve.
7.Fault in the control unit's driver
Rare.
Step-by-step diagnostic guide
- 1
Read codes
Read all codes and look at rail pressure and regulator duty cycle in live data.
- 2
Check signal and ground
With the ignition on and the fuel volume regulator / shutoff valve plugged in, back-probe the signal and ground wires. A signal stuck at reference or battery voltage points to an open ground/signal wire or a short to voltage.
Multimeter: Ground wire to battery negative: below about 0.1 V. Signal stuck at about 5 V (or 12 V) = open or short to voltage.
- 3
Inspect connector and wiring
Inspect the connector on the pump and the harness for damage, fuel contamination and corrosion.
- 4
Measure the solenoid
Unplug the valve and measure its resistance; check the supply and control wires.
Multimeter: Many metering valves read about 2–6 Ω; check the specification.
- 5
Check fuel quality
Drain water from the filter and check the old filter and fuel for contamination.
- 6
Replace and adapt
Replace the valve or repair the wiring; on some engines a pump or rail pressure adaptation must be run afterwards.
Frequently asked questions
Can I keep driving with P0004?
Not recommended. The engine may go into limp mode, cut out or fail to restart.
How much does it cost to fix P0004?
Typical repair costs are 30 € – 800 €, depending on the cause and the vehicle. The most common fixes are: open circuit in the signal or ground wire; signal wire shorted to the 5 V reference or battery voltage; faulty fuel volume regulator / shutoff valve. Always confirm the cause with the tests above before buying parts.
Is the volume regulator part of the high-pressure pump?
It is mounted on the pump, but on many engines it is available as a separate part.
Can bad fuel cause these codes?
Yes. Dirt and water can make the metering valve stick, which shows as range/performance codes or rail pressure faults.
What is the difference between P0004 and similar codes?
P0004 belongs to a group of codes for the same component that differ in the type or location of the fault: P0001 – Fuel Volume Regulator Control Circuit / Open; P0002 – Fuel Volume Regulator Control Circuit Range/Performance; P0003 – Fuel Volume Regulator Control Circuit Low; P0005 – Fuel Shutoff Valve Control Circuit / Open; P0006 – Fuel Shutoff Valve Control Circuit Low; P0007 – Fuel Shutoff Valve Control Circuit High. The tests on this page apply to the whole group; the type of fault tells you where to start.
Related fault codes
This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.