P0118 Engine Coolant Temperature Circuit High
The ECT sensor reports an unrealistically cold reading (high voltage), often an open circuit.
Common causes
- Unplugged or corroded connector
- Open wiring
- Faulty sensor
Symptoms
- Check engine light
- Rich running
- Black smoke on diesels
- Fan runs constantly
What to check
- Check connector
- Check for an open circuit
- Replace sensor if out of range
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0118, follow the service information for that make and model.