1. If your car suffering weak acceleration, unstable idling, power loss from the engine and the "check engine" indicator light up permanently in the meter cluster, it might be due to the coolant temperature sensor faulty. Suggest to diagnose at workshop.
2. Coolant temperature sensor is install at the engine water jacket or coolant hose, it is in contact with the coolant to detect the coolant temperature. ECU receive the temperature signal and adjust the fuel spraying and ignition timing. When the coolant temperature sensor is faulty, the engine could not calculate the fuel spraying amount accurately, which cause the engine shaking or produce black smoke and the power output is affected as well. Suggest to repair at workshop.
3. Besides, owner can open the front bonnet and check if the radiator fan is running at high speed. When the coolant temperature sensor is faulty, the radiator fan will run at high speed. Driving the car for a short period of time is fine but driving for long hours may cause engine overheating. If could not top up the water on time it might damage the engine, suggest to repair at workshop.
Suggest to diagnose at workshop, usually the keypoints of diagnose are:
1. Use the digital high impedance multimeter to test the impedance between the two terminals of the sensor to detect the problem.
2. Repair or replace the coolant temperature sensor.
3. Cold start the car, test if the problem has been resolved.