The sensor signal is low, which reads as a very hot engine. The driver may notice the fan running constantly or a hard cold start.
Likely causes, most common first
- Short to ground in the wiring
- Faulty coolant temperature sensor
- Damaged connector
- Real overheating
Parts usually involved
- Coolant temperature sensor
- Sensor connector
Test before you replace
Confirm the actual engine temperature, then unplug the sensor and watch whether the reading changes.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.