1, water temperature sensor failure; 2. Line failure; There is something wrong with the water thermometer on the dashboard of the car. If the water temperature meter drops while the vehicle is driving, we can use the elimination method to detect and find the plug of the vehicle water temperature sensor, and then see if the water temperature meter of our vehicle can float. If it doesn't float, it means that the vehicle line and water temperature meter are out of order. If it floats, it means that the water temperature sensor is out of order, and we can go to the 4S shop or automobile maintenance center in the corresponding place for maintenance. If the pointer of the water thermometer remains motionless, it is usually that the instrument of the vehicle is damaged and the water temperature data cannot be directly fed back, or the responsiveness of the vehicle water temperature sensor is damaged and the feedback voltage is abnormal, or the vehicle circuit is loose, resulting in excessive resistance of the vehicle line, which will also cause abnormal display of the water thermometer. If the car belongs to the liquid crystal display instrument, the vehicle-mounted instrument can display the vehicle data by itself, and it is possible that the liquid crystal instrument is defined as a vehicle failure state during the driving of the vehicle, so we need to manually adjust the button of the display and adjust it back. Tip: Don't raise the vehicle speed too high when driving, and don't turn on the warm air in a hurry, and then turn on the warm air when the water temperature is normal.