The S7-S8-S9-X7-X9-X90-X95 Water Level Sensor is located internally behind the wall where the
Water Tank sits. It works in conjunction with the magnetic float in the Water Tank to detect the water tank is filled. If you are receiving a "Fill Water Tank" message when the tank is full, then this sensor may be defective. Before ordering the sensor, make sure the water tank float is not stuck in the down position. Scale deposits in the water tank can prevent the float from rising and making contact with the internal magnetic sensor.