Fuel and injectionGeneric OBD-II codeUrgency: Garage soon
Code P0004: fuel volume regulator: circuit high
P0004 means: fuel volume regulator "A": high signal in the control circuit.[1][2] The ECU monitors the fuel metering valve circuit and has detected a high signal (voltage above what is expected). On many common-rail diesels that valve sits on the high-pressure pump and regulates the fuel that reaches it.[1][2]
What code P0004 means
The ECU monitors the fuel metering valve circuit and has detected a high signal (voltage above what is expected). On many common-rail diesels that valve sits on the high-pressure pump and regulates the fuel that reaches it.[1][2]
It is a fault in the valve's electrical circuit (short to positive or a fault in the valve itself), not a fuel quality problem.[1][2]
Original definition (SAE J2012): Fuel Volume Regulator Control Circuit High[1][2]
Causes of P0004
From most to least likely, according to the sources.
Symptoms
- Engine warning light on.[1][2]Engine warning light: faults that cause it
- Lack of power.[1][2]Less power: faults that cause it
- Stalling at low revs and uneven idle.[2]Engine stalls: faults that cause it
- In some cases, the engine will not start.[1]Hard to start: faults that cause it
How to diagnose P0004
In order: from the most likely and cheapest to check to the most expensive.
- 1Read the associated codes (for example P0087 or P0088, for fuel pressure) and the rail pressure data.[2]
- 2Visually inspect the valve and its connector: the wiring harness is where many of these faults are found.[1][2]
- 3Check the battery and charging system voltage; high signals are often caused by excessive voltages or shorts to positive.[1][2]
- 4Measure the valve's resistance and the control voltage; if both are correct, have the ECU checked.[1][2]
Can I keep driving with P0004?
Garage soon
The car may lose power, stall or fail to start; take it to a garage without delay and do not keep cranking the engine.[1][2]
Documented faults related to P0004
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Injectors: the most serious faults by engine and car
- High severityFrequency: Very frequentOM651Delphi piezo injector failure (220/250 CDI)Yes: 220 and 250 CDI models built between 2008 and 2011 had Delphi piezo injectors that were prone to failing and seizing in the cylinder head. Mercedes-Benz replaced them under warranty in 2009 and switched the 220 CDI to solenoid injectors from 2010-2011, but the 250 CDI kept them.Repair (garage): €3,600–€5,900
- High severityFrequency: CommonBMW N52 / N53N53 piezoelectric injector failureThe N53's piezoelectric direct injectors fail frequently and cause misfires, rough idle and limp mode; replacing them is expensive and they must be coded.
- High severityFrequency: CommonMZR-CDOil dilution from leaking injector seals and DPF regenerationsOn the 2.0 and 2.2 MZR-CD, injector seals that age badly and incomplete particulate filter regenerations on short journeys can let unburnt diesel into the sump, diluting the oil and leaving the engine with less lubrication.
- High severityFrequency: CommonOM642Wear and failure of the Bosch piezo injectorsThe OM642's Bosch piezo injectors can fail from around 150,000-200,000 km, especially with poor-quality diesel; they cannot be repaired, only replaced. Because it is a V engine, those on the rear bank are harder to reach, which pushes up labour costs.Repair: €4,500–€6,500
Fuel pump and high-pressure pump: the most serious faults by engine and car
- Critical severityFrequency: Common2.0 and 2.5 HybridLow-pressure fuel pump failure: loss of power and fire riskYes: a low-pressure fuel pump with a defective impeller (Denso) affects millions of Toyotas and Lexuses, including Corolla, C-HR, RAV4 and Camry models with these engines. It can cause loss of power or stalling, and in the EU there is also a risk of leaks and fire on 2018-2022 Corolla, C-HR and Auris models.
- High severityFrequency: CommonBMW N54/N55High-pressure fuel pump (HPFP) failureThe N54's high-pressure pump is one of its best-documented failures: most units will have had it replaced at some point. It warns of itself with long cranking and loss of power; the 2010 campaign was US-only.
- High severityFrequency: Common2.2/2.5 dCiInjection pump or injector failureThe 2.2 dCi's common rail injectors fail fairly often on the X-Trail and Almera, with cases of seizing and leaks; on the Almera with the older YD22DDT, the documented fault is in the injection pump electronics, not the injectors.
- High severityFrequency: CommonVW 2.0 TFSI EA113Wear of the high-pressure pump cam followerYes: the 2.0 TFSI EA113's high-pressure fuel pump is driven by the camshaft through a follower (tappet) that wears; if it wears through it can damage the pump or the camshaft, so it should be checked and replaced as a preventive measure.Repair (garage): €250–€900Appears at around 90,000 km
Wiring, connectors and short circuits: the most serious faults by engine and car
- Critical severityFrequency: OccasionalBMW N62 / N63Additional turbo coolant pump with a risk of short circuit and fireIn 2011 BMW recalled 5, 6 and 7 Series, X5 and X6 models built between 2007 and 2011 because of the additional turbo coolant pump: moisture, a short circuit and, in extreme cases, a fire. In 2012 there was another campaign for a crack in the pump, with a more robust version.
- High severityFrequency: Occasional1.3 TCeBlown fuel pump fuseOn the Renault Captur II and Clio V with the 1.3 TCe engine, a 20-amp fuse can blow and leave the car without an engine. According to L'argus, in April 2021 this fault still had no factory fix; the official service centre's diagnosis includes checking, and sometimes replacing, the catalytic converter.
- High severityFrequency: OccasionalM264/M254Poorly tightened 48 V earth wiring in the mild-hybrid system (fire risk)Mercedes-Benz has issued several recalls (2022-2025) because the 12 V and 48 V earth connections of some cars with a 48 V system may be poorly tightened: resistance rises, the connection heats up and a fire cannot be ruled out. The official workshop checks them and repairs them if necessary in an hour or more.
- High severityFrequency: Occasional1.9 TDIUnit injector tappet wear and injector wiring damageOn the unit injector system, the tappets that operate the injectors can wear if the oil is not changed on time, and the injector wiring can be damaged by contact with oil, causing misfires or loss of power.
- Critical severityFrequency: CommonRover 75Seat SRS connector fault with airbag and seatbelt warning light onAuto Express warns that the Rover 75's seat SRS connector can cause the airbags to fail, and dealers were fixing it with revised connectors. The Dutch APK inspection puts the airbag or seatbelt fault warning among the most frequent defects across almost all series.
- Critical severityFrequency: OccasionalAlfa Romeo GiuliettaShort circuit from badly routed wiring that can prevent gear shifting (KBA campaign, 2010-2015)Yes: according to Germany's KBA, on Alfa Romeo Giulietta cars built between 2010 and 2015 inadequate cable routing could cause a short circuit and, as a result, gear-shift failure.
Control units and comfort electronics (BSI, SAM...): the most serious faults by engine and car
- High severityFrequency: CommonPeugeot 408Electronic faults with the doors, boot and screen (suspected BSI control unit)In 2025 Peugeot recalled around 60,000 2023-2024 Peugeot 308 and 408 cars (code MUV) over a software fault in the door control unit that can cause unintended opening or closing and disable the anti-trap protection on the windows; 408 owners also describe a power boot lid that will not open or close and a screen that goes black.
- High severityFrequency: CommonRenault Laguna IIMultiplex electrical system and hands-free card faultsThe Laguna II had a reputation problem because of faults in its multiplexed electrical network: the hands-free card, the card reader and the ABS, ESP and handbrake warning lights came on erratically, especially in the early years of production (2001-2003).
- Critical severityFrequency: OccasionalMazda MX-5 IVDC/DC converter control unit fault with risk of short circuit and fireA 2018 Safety Gate alert covers MX-5 ND models built between August 2014 and April 2017: the DC converter control unit could fail, cause a short circuit and damage the converter, with a risk of fire. It is a precautionary recall; check the chassis number at the official service centre.
- Medium severityFrequency: Very frequentFiat StiloElectrical and electronic faults in the multiplex systemThe Stilo has had a reputation for widespread electrical faults since its launch: poor contacts in the multiplex wiring, an instrument cluster that switches off and sensors that disconnect, sometimes while the car is running.
Frequently asked questions
What does code P0004 mean?
That the ECU has detected a high signal in the control circuit of the fuel volume regulator, the valve that meters fuel to the high-pressure pump.[1][2]
Is it the same as P0010 or P0011?
No. P0004 belongs to the fuel system; P001x and P0011 relate to variable valve timing (camshaft).[1]
Can I drive with P0004?
It is not advisable: there may be a loss of power, stalling or starting problems. The sensible thing is to take it to a garage soon.[1][2]
Will I pass the MOT with code P0004?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[3]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- P0004 – Fuel volume regulator control – circuit highTroubleCodes.net · Technical documentation · consulted 29 October 2026
- P0004 Code Symptoms, Causes, Diagnosis & Repair Costs GuideFlagship One (FS1 Inc.) · Technical documentation · consulted 29 October 2026
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish