Fuel and injectionGeneric OBD-II codeUrgency: As soon as possible
Code P0093: large fuel system leak
P0093 means: fuel system leak detected: large leak.[1][2] The ECU has detected that the high-pressure fuel circuit is losing pressure abnormally: the rail does not reach, or does not hold, the pressure it is asked for. On a common rail, the ECU continuously monitors the rail's internal pressure from the moment the engine starts and, according to a workshop manual, it stores this code when the pressure drop before and after injection exceeds a threshold several times.[2][3]
What code P0093 means
The ECU has detected that the high-pressure fuel circuit is losing pressure abnormally: the rail does not reach, or does not hold, the pressure it is asked for. On a common rail, the ECU continuously monitors the rail's internal pressure from the moment the engine starts and, according to a workshop manual, it stores this code when the pressure drop before and after injection exceeds a threshold several times.[2][3]
The name of the code is misleading: fuel is not always dripping outside. Baileys Diesel, a diesel specialist, stresses that it refers to an internal pressure loss in the high-pressure circuit (such as the one caused by excessive injector return) and not to an external leak. Autodoc Club, on the other hand, states that with this code the leak is usually clearly visible. As the sources do not agree, if there is a smell of fuel or stains, treat it as a real leak.[1][4]
On some petrol Fords (the sources cite the 2017 Edge and the 3.5 EcoBoost) the diagnostic procedure associates this code with an unmetered air leak, for example in the crankcase ventilation (PCV), and not with a fuel leak.[3][5]
It is a generic OBD-II code (it starts with P0), so the name and number are the same on any make; what changes from one engine to another is how it is detected and what the most likely cause is.[1][5][6]
Original definition (SAE J2012): Fuel System Leak Detected - Large Leak[1][2]
Causes of P0093
From most to least likely, according to the sources.
- 1Injectors with an internal leak or excessive return flow, which let rail pressure escape without any fuel being visible outside; according to one source, this is more common on Bosch systems than on Denso ones.[1][2][3][4]
- 2Leaking high-pressure pipes, fittings or rail: cracked, loose or poorly tightened.[1][2][3][4]
- 3Failing rail pressure limiter or relief valve, or a pressure regulator stuck open.[2][3][4]
- 4High-pressure pump or its control valve (metering valve or SCV), worn or faulty, which cannot hold pressure.[1][2][3][4]
- 5Poor low-pressure supply: air in the circuit, a clogged filter or a weak lift pump.[2][3][4]
- 6Faulty or drifting rail pressure sensor; a falsely low reading can mimic a leak that does not exist.[1][2][3][4]
- 7Contaminated fuel, fuel containing air, or the wrong fuel.[3][4]
- 8Aftermarket power boxes ("piggyback" units) that raise rail pressure above what the system is designed to withstand.[4]
- 9On some petrol Fords, an unmetered intake air leak (for example, in the crankcase ventilation), not a fuel leak.[3][5]
Symptoms
- Engine warning light permanently on.[1][4][5]Engine warning light: faults that cause it
- Hard or impossible starting: the engine is slow to start or does not start.[1][3][4][5]Hard to start: faults that cause it
- Noticeable loss of power when driving.[1][4][5]Less power: faults that cause it
- The engine may go into limp mode, with power limited.[3][4]Limp mode: faults that cause it
- The engine may stall; according to a workshop manual, the ECU may cut injection and the supply pump and stop the engine.[2][3][4][5]Engine stalls: faults that cause it
- Uneven running, with hesitation and jerking when accelerating.[1][3][4]Jerking: faults that cause it
- Smell of diesel or petrol around the car or in the engine bay.[1][3]Fuel smell: faults that cause it
- Thick white smoke from the exhaust on diesels, from unburnt fuel.[4][5]
- Increased fuel consumption.[1][5]Uses more fuel: faults that cause it
How to diagnose P0093
In order: from the most likely and cheapest to check to the most expensive.
- 1First of all, sniff and look: smell of fuel, puddles or stains under the car or in the engine bay. If there are any, do not start the engine or carry on driving.[1][3]
- 2Check that there is enough fuel (if it had run low, refuel and see whether the code comes back) and read the other codes and the freeze-frame data: if there are other rail pressure codes, such as P0087 or P0088, they must be taken into account.[2][3]
- 3With the system depressurised, visually inspect the high-pressure pipes, fittings, rail and injectors for weeping, cracks or loose parts. Never loosen a rail pipe under pressure: work on the high-pressure circuit is a job for a workshop.[1][3][5]
- 4Change the fuel filter if it is dirty, bleed the air from the circuit and check whether the code reappears.[2][4]
- 5With a scan tool, watch the rail pressure live and compare it with the requested pressure. A rapid pressure drop when the engine is switched off gives away a leak in the high-pressure circuit (injector, regulator, metering valve or pump).[2][3][4][7]
- 6Locate the leaking injector: measure each injector's return flow (internal leak or "back-leak"), or use the per-cylinder fuel cut-off test and the active leak test, if the scan tool allows it.[2][3]
- 7Check the operation of the high-pressure pump with its control valve and of the pressure limiter valve, and verify that the rail pressure sensor reads correctly.[3][4]
- 8If an injector is replaced, the circuit must be bled again and the new injector's correction code registered in the ECU.
Can I keep driving with P0093?
As soon as possible
The sources agree that it is urgent. Autodoc Club and AutoDTCs say you should not carry on driving: a large leak in a high-pressure circuit is a real fire risk and, according to Autodoc, you should stop the car and call a tow truck. Baileys Diesel describes it as an urgent fault that can end in engine damage or unexpected stalling, and CarParts.com as a serious code that must be dealt with immediately because any leak in the fuel system is dangerous. A workshop manual also states that, once the code is stored, the ECU may cut injection and the supply pump and stop the engine. They disagree on whether the leak is usually visible; as a precaution, if there is a smell of fuel or stains, do not start the engine or drive.[1][2][3][4][5]
Documented faults related to P0093
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
Fuel leaks: the most serious faults by engine and car
- High severityFrequency: Common1.4 and 1.6 8vLPG tank corrosionOn the factory LPG versions of the Dacia Sandero I, several reports document corrosion of the gas tank, picked up at the vehicle inspection and a reason for failing it. It is not a fault of the engine itself, but of the LPG system that Dacia fitted to this engine.Appears at around 65,000 km
- Critical severityFrequency: Occasional1.5 EcoBoostFuel leak from cracked injectors, with a fire risk (Kuga Dragon)Yes: Ford has recalled the Kuga with the three-cylinder 1.5 EcoBoost because a high-pressure injector can crack and release fuel onto the engine, with a fire risk. The broadest campaign, 25S76 (2026), covers units built between 2018 and 2024.
- High severityFrequency: Occasional2.2 JTDm Multijet IIDiesel leak from the fuel filter gasketAlfa Romeo recalled 3,873 2018 Giulia with the 2.2 diesel over a faulty fuel filter gasket that caused diesel leaks (according to Alvolante). The source gives no date or reference for the campaign and cites no real failures.
- High severityFrequency: OccasionalAudi 3.0 TFSI V6Fuel leak at the injection rails (2015 and 2019 campaigns)Audi recalled cars with the 3.0 TFSI over possible leaks from the fuel rails: one campaign in 2015 (built between April 2011 and April 2012) and another in 2019 (low-pressure rails, built between 2014 and 2016). You notice it by a smell of petrol; the fix is to replace the rails.
- Critical severityFrequency: OccasionalDacia Logan IIIDefective LPG tank weld with risk of gas leakAn incorrect weld on the LPG tank can cause gas leaks with a risk of fire. It affects LPG Logan III, Sandero III and Duster cars built between 6 February and 3 July 2023 (Dacia code 0E5T, Safety Gate alert 45/2023).
- Critical severityFrequency: OccasionalFord Transit VI-VIICorrosion of the natural gas tank multivalve on the Transit CNGIn December 2017 Safety Gate recorded alert A12/1818/17: on the natural gas (CNG) Transit built between 2003 and 2011 (types DM2-CNG and DA3-CNG), the system's multivalve may corrode and, in the event of a fire, the pressure relief device could fail and the tank could explode.
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
Can I drive with code P0093?
It is not advisable. Autodoc Club and AutoDTCs state that you should not carry on driving, because of the fire risk from a large high-pressure fuel leak, and other sources warn that the engine may stall or fail to start. If there is a smell of fuel or stains, do not start the car and call a tow truck.[1][2][3][4]
Does code P0093 mean fuel is dripping?
Not always. On a diesel common rail it is usually an internal pressure loss, for example from an injector with excessive return flow, rather than fuel escaping outside; but there can also be external leaks at pipes, fittings or the rail, and one source states that the leak is usually visible. If you smell fuel or see stains, treat it as a real leak.[1][4]
How is P0093 diagnosed?
You start with a visual inspection with the system depressurised, reading other codes and checking the fuel and the filter. Then you watch the rail pressure live and look for the leaking injector (return flow per injector, per-cylinder cut-off) and, lastly, you check the high-pressure pump, the limiter valve and the sensor.[2][3][4]
Can I repair it myself?
Only simple tasks, such as a hose connection. On the high-pressure circuit you must not loosen any rail pipe under pressure, and Autodoc Club recommends going to a specialist for the more complex jobs because of the fire risk.[1][5]
Does P0093 mean the same on all makes?
The code and its name are the same for all manufacturers, because those that start with P0 are generic, but the thresholds and the way it is detected vary. On some petrol Fords, the diagnostic procedure points to an air leak rather than a fuel leak.[1][3][5][6]
Will I pass the MOT with code P0093?
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.
- Qué significa el código P0093Autodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
- P0093 - СИСТЕМА ECD, Diagnostic DTC:P0093 (extracto de manual de reparación, fabricante no indicado)Corolla Club (corolla-club.ru) · Other source · consulted 2 October 2026
- P0093 – Fuel System Leak Detected Large LeakAutoDTCs · Technical documentation · published July 2026 · consulted 2 October 2026
- P0093 Engine Code Common Causes and SolutionsBaileys Diesel · Technical documentation · published 20 October 2023 · consulted 2 October 2026
- P0093 Code: Fuel System Large Leak Detected - In The Garage with CarParts.comCarParts.com · Technical documentation · published 27 June 2024 · consulted 2 October 2026
- On-board diagnosticsWikipedia · Other source · consulted 2 October 2026
- CRD (Bosch) fuel rail pressure sensor | Automotive oscilloscope testPico Technology · Technical documentation · consulted 2 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