P0118 Engine Coolant Temperature Circuit High Input
What does P0118 mean?
P0118 — Engine Coolant Temperature Circuit High Input. This is an OBD-II diagnostic trouble code a scanner retrieves when your vehicle's computer detects engine coolant temperature circuit high input. The level of risk depends on how the vehicle is currently running and how long you've been driving with the light on.
Common causes of P0118
- Open circuit in the ECT sensor signal wire
- Faulty engine coolant temperature sensor
- Poor connector connection or corroded terminals
- Low coolant level causing false readings
- PCM fault
How to fix P0118
- Check engine coolant level and top off if low
- Inspect ECT sensor wiring and connector for opens or corrosion
- Compare ECT reading on an OBD-II scanner with engine temperature
- Verify sensor signal and ground circuits at the connector
- Replace the ECT sensor if the circuit tests point to it