P0115 Engine Coolant Temperature Circuit
Electrical fault in the engine coolant temperature (ECT) sensor circuit.
Common causes
- Faulty ECT sensor
- Damaged wiring or connector
- Low coolant level
Symptoms
- Check engine light
- Cooling fan running all the time
- Hard starting
- Poor fuel economy
What to check
- Check coolant level
- Compare ECT with ambient on a cold engine
- Inspect connector
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0115, follow the service information for that make and model.