Engine and gearbox (P)
P0117: Coolant temperature sensor low input
The engine control unit detects that the voltage from the coolant temperature sensor is lower than expected. This can affect engine performance and fuel efficiency.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Engine runs poorly
- Increased fuel consumption
- Check engine light on
Common causes
- Short to ground
- Sensor failure
- Connector corrosion
How to check it yourself
- Compare cold reading to ambient temperature
- Inspect sensor and wiring for damage
- Check reference and ground circuit
Can I keep driving?
The car can still be driven, but it may run inefficiently.
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