Fuel and injectionGeneric OBD-II codeUrgency: Garage soon
Code P0090: pressure regulator circuit fault
P0090 means: fuel pressure regulator "1" control circuit.[1][2][3] The ECU has detected an electrical fault in the circuit that controls fuel pressure regulator "1". According to AutoDTCs, it is usually an open circuit or high resistance in the solenoid that meters the high-pressure fuel in a direct injection engine: the ECU can no longer operate it reliably and loses the ability to regulate injection pressure. TaT speaks of open circuits or short circuits in the wiring, the connectors or the regulator driver, and Autodoc Club describes it as a fault in the control circuit of fuel metering valve "A", with an open circuit.[1][2][3]
What code P0090 means
The ECU has detected an electrical fault in the circuit that controls fuel pressure regulator "1". According to AutoDTCs, it is usually an open circuit or high resistance in the solenoid that meters the high-pressure fuel in a direct injection engine: the ECU can no longer operate it reliably and loses the ability to regulate injection pressure. TaT speaks of open circuits or short circuits in the wiring, the connectors or the regulator driver, and Autodoc Club describes it as a fault in the control circuit of fuel metering valve "A", with an open circuit.[1][2][3]
According to Pico, on a Bosch common rail that valve is driven by a pulse-width modulated (PWM) signal: the ECU opens it to send fuel back to the return and lower the pressure, and closes it to raise it; the higher the duty cycle, the higher the average current and the greater the valve's displacement. Pico lists codes P0087 to P0094 among those of the pressure regulating valve, and P0001 to P0004, P0087, P0088 and P0251 to P0255 among those of the pump's flow control valve.[4][5]
It is an electrical circuit code, different from P0089. According to AutoDTCs, P0089 is a performance fault (it checks whether the rail pressure follows the requested pressure), not an open wire or a short circuit, and it points more to a mechanical or fuel supply problem than to the valve wiring; codes P0090 to P0092, on the other hand, are circuit codes. AutoDTCs adds that P0090 can appear together with pressure codes such as P0087.[2][6]
It is a generic OBD-II code (it starts with P0), so it means the same on any brand; what changes from one engine to another is the most likely cause.[3][7]
Original definition (SAE J2012): Fuel Pressure Regulator 1 Control Circuit[1][2][3]
Causes of P0090
From most to least likely, according to the sources.
- 1Loose or corroded regulator or metering valve connector (on the high-pressure pump), with backed-out terminals or oxidised contacts. AutoDTCs gives this as the most common trigger.[1][2]
- 2Broken, high-resistance or damaged control wire: chafing, deteriorated insulation or a short circuit in the loom.[1][2]
- 3Faulty regulator or metering valve, with an open solenoid or resistance out of range. Autodoc Club lists it as the first cause; AutoDTCs, as the fourth.[1][2]
- 4Faulty fuse in the control circuit (Autodoc Club) or poor power supply or ground in the actuator circuit (AutoDTCs).[1][2]
- 5Failed ECU output driver: both sources leave it for last, only once the wiring and the solenoid have been checked.[1][2]
Symptoms
- Engine warning light (check engine light) on, often from the first fault.[2]Engine warning light: faults that cause it
- Long or difficult starting, or not starting at all if the regulator cannot build the requested pressure.[1][2]Hard to start: faults that cause it
- Rough idle.[1][2]Vibrations: faults that cause it
- Loss of power, especially when accelerating, and misfires at different engine speeds.[1][2]Less power: faults that cause it
- Jerking and hesitation, especially when accelerating.[2]Jerking: faults that cause it
- The engine may stall or cut out, especially under load.[2]Engine stalls: faults that cause it
- Reduced power or limp mode: AutoDTCs says the car may limit power because the ECU cannot regulate injection pressure, and describes this as typical on General Motors vehicles.[2]Limp mode: faults that cause it
- Black or white smoke from the exhaust.[1]Black smoke: faults that cause it
- Noticeable increase in fuel consumption.[1]Uses more fuel: faults that cause it
How to diagnose P0090
In order: from the most likely and cheapest to check to the most expensive.
- 1Read the code and the freeze frame data with a diagnostic tool and look at the other stored codes: P0091 and P0092 (same circuit) and rail pressure codes such as P0087.[2]
- 2Inspect the regulator connector (on the high-pressure pump) and the ECU connector: corrosion, open or backed-out terminals, moisture. Clean them with contact spray and check there is no chafing or damage to the loom. With the engine running, wiggle the loom while watching the tool's data to detect an intermittent fault.[1][2]
- 3Check the fuel control circuit fuses and the actuator's power supply and ground before suspecting expensive parts.[1][2]
- 4With a bidirectional test, command the regulator to switch on and off while watching the circuit status parameters: if they show "malfunction", the fault is active.[2]
- 5With the circuit de-energised and the connectors unplugged, measure the continuity and resistance between the ECU pin and the actuator pin, and rule out short circuits in the wiring. An open circuit or high resistance confirms the fault.[1][2]
- 6Measure the resistance of the solenoid winding and compare it with the manufacturer's specification. Pico shows what the control signal looks like on an oscilloscope (voltage, duty cycle and frequency) with the engine running.[2][4][5]
- 7Only when the wiring and the solenoid are fine, suspect the ECU driver: replacing it without first checking everything above is an expensive mistake.[1][2]
Can I keep driving with P0090?
Garage soon
The sources do not entirely agree on severity. Autodoc Club says short trips are possible but the fault must be repaired soon, because the injection system is affected and the engine can suffer damage. AutoDTCs classes it as high severity and risky: with no regulation of injection pressure, the car can end up with reduced power, be hard to start or stall, so it recommends driving only as far as the garage and avoiding loads or towing. The prudent course is to go to the garage without making more journeys than necessary.[1][2]
Documented faults related to P0090
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 severityCommonFrequency: 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 severityCommonFrequency: 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 severityCommonFrequency: 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 severityCommonFrequency: 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 severityOccasionalFrequency: 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 severityOccasionalFrequency: 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 severityOccasionalFrequency: 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 severityOccasionalFrequency: 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 severityOccasionalFrequency: 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.
- Critical severityOccasionalFrequency: OccasionalAudi A4 B9Risk of short circuit and fire due to moisture in electrical componentsAudi recalled A4 B9 units built between May 2017 and March 2020 because moisture can seep into an electrical component and cause a short circuit, with a risk of the vehicle catching fire.Repair: €0
Control units and comfort electronics (BSI, SAM...): the most serious faults by engine and car
- High severityCommonFrequency: 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 severityCommonFrequency: 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 severityOccasionalFrequency: 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 severityVery frequentFrequency: 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 is the difference between P0090 and P0089?
P0090 is an electrical fault in the circuit that operates the pressure regulator (open, high resistance or short circuit), whereas P0089 is a performance fault: according to AutoDTCs, it checks whether the rail pressure follows the requested pressure and points more to a mechanical or supply problem than to the wiring. P0091 and P0092 belong to the same circuit as P0090.[2][3][6]
Can I drive with code P0090?
Only as much as you need to get to the garage. Autodoc Club accepts short trips but asks for it to be repaired soon, and AutoDTCs considers it risky: there may be loss of power, difficulty starting or stalling because the ECU is not regulating injection pressure.[1][2]
Does P0090 mean the regulator or the high-pressure pump has to be replaced?
Not necessarily. The first suspicion is electrical: connector, wiring, fuse or power supply. Then comes the regulator solenoid or the metering valve, and the ECU is left for last. It is worth measuring continuity and resistance before replacing parts.[1][2]
Does P0090 mean the same on all brands?
Yes. Codes starting with P0 are generic OBD-II codes and have the same definition for all manufacturers; what varies from one engine to another is the part that usually fails.[3][7]
Will I pass the MOT with code P0090?
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.[8]
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.
- 1.Código OBD2 P0090: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 4 October 2026 · in Spanish
- 2.P0090 – Fuel Pressure Regulator 1 Control CircuitAutoDTCs · Technical documentation · consulted 4 October 2026
- 3.P0090 — Fuel Pressure Regulator 1 Control CircuitThe Automotive Technician (TaT) · Technical documentation · consulted 4 October 2026
- 4.CRD (Bosch) pressure regulating valvePico Technology · Technical documentation · consulted 4 October 2026
- 5.CRD (Bosch) quantity control valvePico Technology · Technical documentation · consulted 4 October 2026
- 6.P0089 – Fuel Pressure Regulator 1 Performance — Causes & FixAutoDTCs · Technical documentation · consulted 4 October 2026
- 7.On-board diagnosticsWikipedia · Other source · consulted 4 October 2026
- 8.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