Function of water temperature sensor
Is to convert the cooling water temperature into an electrical signal. After input into ECU, there are:
1. Correct the fuel injection quantity; When the temperature is low, increase the injection quantity.

2. Correct the ignition advance angle; Increase the ignition advance angle at low temperature, and delay the ignition to prevent deflagration at high temperature.
3. Affect idle speed control valve; At low temperature, ECU controls the action of idle control valve according to the water temperature sensing signal to increase the speed.
4. Affect EGR valve;
When the water temperature sensor fails, the temperature signal when the engine is cold is still displayed when the engine is hot. The ECU can only supply the engine with thinner mixture (signal when the engine is hot), so it is difficult to start the engine when the engine is cold.