A．When testing some sensors, if the buzzer has continuously ring all along, 1. please check whether some parts of the car or some unnecessary objects enter into the detecting range; 2. Or whether the holes are too small so as that the sensors cannot detect effectively; 3. Or whether the sensors are too close to some strong interference sources (such as, exhaust pipe or other wires);

　　B. If the buzzer alarms at a clear place and the display shows distance figure, but there are nothing in front of the sensor, then it is possible that the sensors are detecting the ground, please check the position and direction of the sensor; Or the sensors maybe detect some parts of the car.

　　C. If above problems couldn’t be solved yet, then the whole system should be replaced;