Water level sensor is equivalent to pressure switch. When you set a pressure value, the water pressure will be generated after water injection, and the electricity will be automatically turned on after the pressure value is reached. The water level switch of washing machine can be divided into electronic (adjustable resistance type) and switching type. Both of them are caused by the air pressure generated when the water level rises, which is transmitted to the sensor through the pipeline to make the resistance occur. Change or internal switch is connected to make the computer move. When it is damaged, it will cause inaccurate injection, long injection will not move (run), and after drainage, it will not dry (this situation is relatively rare, because the sensor does not reset). When inspecting and repairing, attention should be paid to check whether the pipeline is broken, whether the seals at both ends are good or not, whether the sensor is leaking, when inspecting the sensor, air can be injected from the air inlet by the nozzle, and at the same time, the resistance at both ends of the sensor can be measured by a meter or whether the switch is on. The screw on the switch sensor is used to adjust the level of water injection. The water level can be adjusted on time.