P0118
Engine Coolant Temperature Circuit High
- Severity
- Medium
- Driving
- Drivable — book it in
The coolant temperature sensor circuit is reading high - outside its valid range. Note that the electrical direction and the temperature direction are opposite on these sensors: resistance falls as temperature rises, so a low circuit reading corresponds to the module seeing an implausibly hot engine, and a high reading to an implausibly cold one. Either way the module falls back to a substitute value.
Possible causes
- CommonShort or open circuit in the sensor wiring
- CommonFailed coolant temperature sensor
- PossibleDisconnected or corroded connector
- RareGenuine overheating, if the reading really is that hot
What you might notice
- Check engine light on
- Cooling fans running constantly or never
- Poor fuel economy
- Harder cold starting
- Temperature gauge at an extreme
What to check, in order
- Read the actual temperature value on the live data screen rather than relying on the code. An implausible extreme confirms an electrical fault; a genuinely high reading needs treating as possible overheating.
- If the reading really does indicate overheating, stop and check coolant level and for leaks before driving further.
- Check the connector is seated and free of corrosion.
- Check the wiring for a short to ground or an open circuit.
- Replace the sensor once wiring is confirmed good.
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