P0094
Fuel System Leak Detected - Small Leak.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- 94
- FaultThe specific fault in that area
What it means
P0094 means the engine control unit has detected a small leak in the high-pressure side of the fuel system. It sets when fuel pressure drops more than expected, or fails to hold after the engine is switched off or while running, compared with what the control unit commanded. The exact monitoring method and the affected components vary by engine and fuel system type.
Symptoms
- Engine malfunction light on
- Long cranking or hard starting, especially when hot
- Rough idle or occasional misfire
- Hesitation or loss of power under load
- Smell of fuel around the engine bay or fuel rail
- Poor fuel economy
Possible causes
- Leaking or weeping fuel injector or injector seal on the high-pressure sidelikely
- Leaking fuel line, fitting or union on the fuel rail or feed pipelikely
- Fuel pressure regulator or pressure control valve leaking or sticking openpossible
- Worn or weak fuel pump unable to hold pressure, or a leaking pump check valvepossible
- Faulty fuel rail pressure sensor giving an inaccurate readingpossible
- Wiring or connector fault affecting the pressure sensor or regulator circuitrare
- Cracked fuel rail or damaged rail sealsrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting fuel rail pressure, engine temperature and load when the fault set.
- Check for other fuel pressure, injector or misfire codes that point towards the cause.
- Visually inspect the fuel rail, lines, unions and injectors for wetness, staining or fuel smell, with the engine cold and no ignition sources nearby.
- Inspect the wiring and connectors to the fuel pressure sensor, pressure regulator and pump for damage, corrosion or looseness.
- Compare live fuel rail pressure with the commanded value at idle, under load and after switch-off, using the manufacturer's specification for that engine.
- Test fuel pressure with a suitable gauge to confirm the sensor reading, and carry out a pressure hold test as the manufacturer specifies.
- Check the pressure regulator or control valve operation and the fuel pump output and delivery volume.
- Check for fuel in the engine oil or on the spark plugs, which can indicate leaking injectors.
How to fix
- Replace leaking injectors or injector seals, following the correct procedure for the engine.
- Repair or replace leaking fuel lines, fittings or rail seals.
- Replace a faulty fuel pressure regulator or pressure control valve.
- Replace a weak fuel pump or a pump with a failed check valve.
- Replace a faulty fuel rail pressure sensor.
- Repair damaged wiring or connectors, then clear the code and road test to confirm it does not return.
Can I keep driving?
High severity
Avoid driving until the fuel leak is found and ruled out, as leaking fuel is a fire risk and can dilute the engine oil. If there is any visible leak or fuel smell, do not drive the car and arrange recovery or repair.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.