OBD2 codes.
A code identifies a signal or system that needs to be checked, not a part you should replace.
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P0117Coolant temperature sensor: signal too lowUrgency medium
Engine Coolant Temperature Sensor 1 Circuit Low
The coolant temperature sensor tells the ECU how hot the engine is. Its voltage falls as the engine warms up.
What the car has detected
The sensor voltage is so low that it would mean a very hot engine: it is usually a wire shorted to earth or the sensor itself.
The ECU may run the fan all the time and use default values, so the car may start badly and use more fuel. If the engine is also really overheating, it is urgent.
Symptoms
- Engine warning light on
- Hard cold starts or rough idle
- Fan running all the time
Possible causes
- Sensor wire shorted to earth
- Faulty coolant temperature sensor
- Engine really overheating because of a cooling fault
Checks for the garage
- Check the coolant level with the engine cold
- Check the sensor wiring and connector
- Compare the live data reading with the expected one
Next step
Ask for the coolant temperature sensor, its wiring and the cooling system to be checked.
Go to a garage soon. If the gauge reads very hot or there is steam, stop the car in a safe place and do not open the tank while hot.