water temp gauge sending unit

• 2023-03-17

The sensor sending unit of the water temp gauge is a thermistor type sensor. It is screwed onto the engine cooling water channel. The thermistor determines the current flowing through the coil winding of the water temperature meter. This will drive the pointer of the meter to swing. Many automobile engine cooling systems use special coolant.

When the engine is cold, the temperature signal is still displayed when the engine is hot. The ECU cannot get the signal to provide too rich mixture. It can only supply the engine with thinner mixture (the signal when the engine is hot), which makes it difficult to start the engine when the engine is cold. In this case, check whether the water temperature sensor plug contacts normally or replace the water temp sending unit. For example, reading the data of the vehicle's static engine (referring to the cold vehicle), it is found that the coolant temperature output by the engine ECU is 105 ℃, while the actual temperature of the engine is only 1 ℃ at this time (set as the temperature in winter). It is obvious that the water temperature signal received by the engine ECU is wrong, indicating that there is a problem with the water temperature sensor.

The method to judge whether the water temp sending unit is damaged is: when the water temperature sensor is damaged, the pointer of the water temperature gauge will not move, no matter how high the water temperature is, the pointer of the water temperature gauge will not move, and will directly point to the highest position. The interior of the automobile water temperature sensor is the automobile water temperature sensor. The lower the temperature, the greater the resistance; On the contrary, the smaller the resistance is, it is installed on the water jacket of the engine block or cylinder head, and directly contacts with the cooling water, so as to measure the temperature of the engine cooling water. If this component is damaged, the water temperature displayed by the water temperature gauge on the instrument panel will not be accurate, and the normal operation of the electronic fan behind the water tank will also be affected. The coolant of the household car needs to be replaced regularly. If the coolant is not replaced for a long time, the dirty things in the coolant may cover the water temp sending unit, which will lead to inaccurate water temperature detected by the water temperature sensor.