The coolant temperature reading does not fit what the computer expects. The driver may notice high consumption or a temperature gauge that behaves oddly.
Likely causes, most common first
- Thermostat stuck open
- Faulty coolant temperature sensor
- Low coolant or air in the system
- Wiring fault
Parts usually involved
- Coolant temperature sensor
- Thermostat
- Sensor connector
Test before you replace
Watch the live temperature during warm-up and compare it with an infrared reading at the housing.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.