Engine and gearbox (P)
P0118: Coolant temperature sensor high input
The engine control unit is receiving a higher than expected voltage signal from the coolant temperature sensor. This may affect engine performance and fuel efficiency.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Check engine light on
- Poor fuel economy
- Engine running rough
- Overheating warning
Common causes
- Open circuit
- Sensor unplugged
- Harness damage
- Faulty coolant temperature sensor
How to check it yourself
- Inspect the sensor connector for damage or corrosion
- Ensure the sensor is properly plugged in
- Check the wiring harness for damage
- Test the sensor signal continuity with a multimeter
Can I keep driving?
If the engine is overheating, do not drive the car. Otherwise, it may be driven with caution to a repair facility.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer