P0168
Fuel Temperature Too High
- Severity
- Medium
- Driving
- Drivable — book it in
The fuel is hotter than the module will accept. Fuel returning from the injection system carries heat back to the tank, and the fuel in the tank is what absorbs it. Hot fuel is less dense, so the same injector opening time delivers less energy - and on a diesel it also lubricates less well.
Possible causes
- CommonRunning the tank persistently low, so there is little fuel to absorb the returning heat
- CommonBlocked or damaged fuel cooler, where one is fitted
- CommonRestricted return line
- CommonFailed fuel temperature sensor reading high
- PossibleSustained heavy work in hot weather - towing, or long climbs
- PossibleExcessive injector leak-off returning large quantities of hot fuel
What you might notice
- Loss of power when hot, recovering after the engine cools
- Poor fuel economy
- Rough running when the tank is low
- Check engine light on
What to check, in order
- Keep the tank fuller. On vehicles that return a lot of fuel this alone can stop the code, and it is worth trying before anything is dismantled.
- Check the fuel temperature reading on live data with the engine cold. It should sit close to ambient; a cold engine reporting hot fuel is a sensor fault.
- Inspect the fuel cooler and its airflow if one is fitted. Road debris packed into the fins stops it working.
- Check the return line for kinks or restriction, particularly after any work in that area.
- Consider injector leak-off. Worn injectors return a great deal of fuel, and that fuel is hot - so this code and a fuel delivery code together point the same way.
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