P0118: Engine coolant temperature sensor circuit high
The ECU sees a voltage that is too high from the engine temperature sensor, as if it were frozen. Usually a loose connector or a broken wire.
| Code | P0118 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
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.
Open the bonnetthe in-depth explanation
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 its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
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 an inspection. It’s all in how to read and clear fault codes and in inspections 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
- P011A Engine coolant temperature sensors 1 and 2 do not agree
- P011B Engine coolant temperature does not match intake air temperature
- P011C Charge air and intake air temperatures on bank 1 do not agree
- 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
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Cooling.
What does code P0118 mean?
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.
Can you drive with P0118?
You can drive, but the ECU does not know the real engine temperature. Watch for overheating and get it to a garage soon.
How do you clear P0118?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0118 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
