P0118: Engine coolant temperature sensor circuit high

What P0118 means

The colder the engine, the higher the voltage this sensor sends. If the voltage rises above what is possible, the ECU reads an absurdly low temperature, often minus 40 degrees. It is almost always an open circuit: an unplugged connector, a broken wire, a loose earth or a sensor broken internally.

Most common causes

• Sensor connector unplugged, loose or with corroded pins
• Broken sensor wire
• Sensor earth broken or loose
• Sensor open internally
• A connector left badly fitted after a thermostat or hose was changed

Symptoms

• Engine warning light on
• Temperature gauge not rising
• Radiator fan running all the time (safety mode)
• Higher fuel consumption and possible black smoke on diesels

Can you drive with P0118?

With care You can drive, but the ECU does not know the real engine temperature. Watch for overheating and get it to a garage soon.

How to check it

If coolant temperature in live data sits at around minus 40 degrees, the ECU cannot see the sensor. First check the connector is fully plugged in, especially if the thermostat or a hose was worked on recently.

How to read and clear P0118 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0118 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0114 Intake air temperature sensor circuit intermittent
• P0115 Engine coolant temperature sensor circuit fault
• P0116 Engine coolant temperature sensor range or performance
• P0117 Engine coolant temperature sensor circuit low
• P0119 Engine coolant temperature sensor circuit intermittent
• P0120 Throttle or pedal position sensor A: circuit fault
• P0121 Throttle or pedal position sensor A: out of expected range
• P0122 Throttle or pedal position sensor A: low signal
• P0100 Mass or volume air flow sensor circuit fault
• P0101 Air flow sensor range or performance problem
• P0102 Air flow sensor circuit low input
• P0103 Air flow sensor circuit high input

P0118 is a generic code, so it means the same on any make, for example on Abarth, Citroën, Cupra, Hyundai, Mini, Seat. See what Final OBD does on your car in makes and models.