Fuel and injectionGeneric OBD-II codeUrgency: Garage soon
Code P0251: injection pump fuel metering control (A)
P0251 means: fuel metering control of injection pump “A” (cam/rotor/injector).[1][2][3] The control unit has detected a problem with the fuel metering control of the injection pump, circuit “A”; the standard's name mentions the cam, the rotor or the injector. According to TaT, it is stored when the fuel pressure or flow deviates from acceptable limits under a specific operating condition.[1][2]
What code P0251 means
The control unit has detected a problem with the fuel metering control of the injection pump, circuit “A”; the standard's name mentions the cam, the rotor or the injector. According to TaT, it is stored when the fuel pressure or flow deviates from acceptable limits under a specific operating condition.[1][2]
PartsAvatar explains it this way: the control unit stores it when the voltage it sends to the electronic fuel control actuator does not match the signal returned by the metering sensor, and says it only affects diesels. CarWiki describes a fault in the pump's fuel valve control circuit. DTCSearch notes that GM describes it as “Injection Pump Camshaft System Conditions”.[3][4][5]
It is a generic code of the OBD-II standard (it starts with P0), so it means the same on any brand. What changes from one engine to another is the most likely cause.[6]
Original definition (SAE J2012): Injection Pump Fuel Metering Control "A" (Cam/Rotor/Injector)[1][2][3]
Causes of P0251
From most to least likely, according to the sources.
- 1Faulty metering regulator or actuator of the injection pump.[4][5]
- 2Faulty injection pump.[4]
- 3Blocked diesel filter or dirty or contaminated fuel system.[4][5]
- 4Damaged circuit wiring or connectors: breaks, short circuits to positive or earth, corrosion or poor contacts.[4][5]
- 5Related sensors that are faulty or misadjusted: crankshaft, camshaft, accelerator pedal, intake air temperature.[4][5]
- 6Worn, blocked or leaking injectors.[4][5]
- 7Faulty control unit. PartsAvatar places it as the last suspect, after checking all the components.[5]
Symptoms
- Engine fault warning light on.[4][5]Engine warning light: faults that cause it
- Juddering or irregular idling.[4]Jerking: faults that cause it
- Loss of power or acceleration.[4][5]Less power: faults that cause it
- Hard starting, or the car will not start.[4][5]Hard to start: faults that cause it
- Stalling and misfiring.[5]Engine stalls: faults that cause it
- Excessive smoke from the exhaust.[5]
- Higher fuel consumption.[4]Uses more fuel: faults that cause it
How to diagnose P0251
In order: from the most likely and cheapest to check to the most expensive.
- 1Check the freeze frame data and the live data of the related sensors: crankshaft, accelerator pedal and intake air temperature.[5]
- 2Check the fuel quality and measure its pressure.[5]
- 3Check the diesel filter and the feed pump, and replace them if necessary.[4][5]
- 4Check the wiring, connectors, fuses and relays of the pump circuit, and measure voltage and resistance with a multimeter.[4][5]
- 5Check the injectors: condition, leaks and blockages.[4][5]
- 6Only after ruling out the above should you repair or replace the injection pump.[4]
- 7Check the control unit last: it may need reprogramming or replacement.[4][5]
Can I keep driving with P0251?
Garage soon
AutoDTCs rates it as moderate in severity and says it normally does not leave you stranded, but among the symptoms the sources cite are stalling and the car not starting. If the car judders or loses power, take it to a workshop soon.[1][5]
Parts related to code P0251
The parts that most often cause this code. The code points to the circuit, not always the part: diagnose before you buy.
Fuel pump
Injector
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Documented faults related to P0251
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
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
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
Engine sensors: the most serious faults by engine and car
- High severityFrequency: Occasional2.0 DTI and 2.2 DTIVP44 injection pump and air mass meter failureGerman Wikipedia documents recurring failures of the Bosch VP44 injection pump and the air mass meter in the early years of this engine. An owner testimony for this engine describes the pump being replaced at 192,500 km, at a cost the owner calls «prohibitive».
- Medium severityFrequency: Common2.0 TDIClogged particulate filter or faulty pressure sensorThe 2.0 TDI's particulate filter clogs if the car mostly makes short journeys, because it never gets to regenerate; sometimes the fault is just the differential pressure sensor. Cleaning it costs around €200 and replacing it, €800 to €3,000.Repair (garage): €800–€3,000
- Medium severityFrequency: Common1.4 and 1.6 8vCrankshaft position sensor failure (TDC sensor)The crankshaft position sensor (capteur PMH, or TDC sensor) appears repeatedly in the reliability sources for the Clio II, the Kangoo I and the Dacia Logan I with this engine, with hard cold starting or stalling as the main symptoms. It is a cheap part, but the failure can leave you stranded.
- Medium severityFrequency: Common1.4 and 1.6 16vCrankshaft position sensor failureThe crankshaft position sensor (capteur PMH) appears repeatedly in the reliability sources for almost every generation with this engine, with hard cold starting, stalling or the car cutting out unexpectedly. It is a cheap part, but the failure can leave you stranded.
Frequently asked questions
Which engines does the P0251 affect?
PartsAvatar states that it only affects diesels. The standard's name mentions the cam, the rotor and the injector, and the sources consulted do not specify which brands or European engines use it.[3][5]
What is the IPR that appears in the guides?
CarWiki refers to it as the “injection pump regulator”: the injection pump regulator. It is the first part it mentions among the causes.[4]
Does the injection pump need replacing?
It is not the first step. CarWiki and PartsAvatar advise checking the filter, the fuel, the sensors, the wiring and the injectors first, and repairing or replacing the pump only if everything else is fine.[4][5]
Will I pass the MOT with code P0251?
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.[7]
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.
- P0251 – Injection Pump Fuel Metering Control "A" (Cam/Rotor/Injector) — AutoDTCsAutoDTCs · Technical documentation · consulted 31 October 2026
- P0251 Fault Code Definition & Info | TaTThe Automotive Technician (TaT) · Technical documentation · consulted 31 October 2026
- p0251 DTC: Injection Pump Fuel Metering Control "A" (Cam/Rotor/Injector)DTCSearch.com (OBD Solutions) · Technical documentation · consulted 31 October 2026
- OBD DTC Fehlercode P0251 | Einspritzpumpe A, Rotor/Nockenring – Fehlfunktion StromkreisCarWiki.de · Technical documentation · consulted 31 October 2026 · in German
- OBD Code P0251 - Injection Pump Fuel Metering Control A Malfunction (Cam/Rotor/Injector)PartsAvatar · Technical documentation · published 13 March 2023 · consulted 31 October 2026
- On-board diagnosticsWikipedia · Other source · consulted 31 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