P0194
Fuel Rail Pressure Sensor Circuit Intermittent
- Severity
- High
- Driving
- Drive only to a garage
The fuel rail pressure signal drops out and returns. Because the module calculates injector opening times from this figure, an intermittent signal makes the engine cut and recover - and an engine that can cut out is a different problem from one that runs badly.
Possible causes
- CommonLoose, corroded or backed-out pin in the sensor connector
- CommonChafed wiring that shorts or opens only when the engine moves on its mounts
- CommonWater or oil that has crept into the connector
- PossiblePoor earth connection
- PossibleFailing sensor breaking down when hot
What you might notice
- Hard starting, or refusing to start at all
- Loss of power, or dropping into limp mode
- Rough running, misfiring, or cutting out
- Smoke from the exhaust
- Check engine light on
What to check, in order
- Wiggle the connector and flex the harness with live data on screen. An intermittent fault that can be reproduced by hand is nearly solved; one that cannot will not be found by guessing.
- Open the connector and look for green corrosion, spread terminals or a pin pushed back out of its housing. Spread terminals are common and easy to miss.
- Check the sensor's earth. A poor earth produces exactly this pattern and replacing the sensor changes nothing.
- Replace the sensor last. Intermittent faults are connections far more often than components, because a component that has failed usually stays failed.
- Log rail pressure while driving rather than testing at idle. A fault that only appears under vibration or load will not show itself on a stationary engine.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering
P0100P0101P0102P0103P0104P0105P0106P0107P0108P0109P0110P0111P0112P0113P0114P0115P0116P0117P0118P0119P0120P0121P0122P0123P0124P0125P0126P0127P0128P0129P0130P0131P0132P0133P0134P0135P0136P0137P0138P0139P0140P0141P0142P0143P0144P0145P0146P0147P0148P0149P0150P0151P0152P0153P0154P0155P0156P0157P0158P0159P0160P0161P0162P0163P0164P0165P0166P0167P0168P0169P0170P0171P0172P0173P0174P0175P0176P0177P0178P0179P0180P0181P0182P0183P0184P0185P0186P0187P0188P0189P0190P0191P0192P0193P0194P0195P0196P0197P0198P0199