How to Test if a Parking Sensor is Working Properly?
4 Answers
You can roughly determine which sensor is malfunctioning by comparing the presence and volume of beeps between several sensors. Parking sensors have blind spots, and in actual maintenance, you can use these blind spots to approach a specific sensor to check for faults. When a parking sensor fails, it will emit a long intermittent "beep" sound to indicate a malfunction in the left sensor.
Every time I reverse, I worry about the reliability of the parking sensors. Testing them is simple: start the vehicle, shift into reverse, and have a friend stand at different distances behind the car. The sensors should beep, with the beeps getting faster as the distance decreases. If there's no sound at all or a delayed response, the sensors might be dirty—clean the circular sensor probes with a damp cloth and try again. If they still don't work, it could be a wiring issue or a blown fuse. Personally, I test them monthly, especially after washing the car, to prevent dirt buildup. For a safer test, use cardboard boxes as obstacles in an empty space—avoid testing in crowded areas. Aging sensors may weaken, producing hoarse or intermittent sounds, which is dangerous and should be fixed promptly. If you can't fix it yourself, take it to a professional shop—they can quickly diagnose issues with voltage tests and other tools.
From a hands-on perspective, testing radar functionality should be done step by step: After shifting into reverse gear, simulate an obstacle by moving your hand in front of the sensor. Under normal conditions, the warning sound should change steadily—speeding up as you get closer and slowing down as you move away. If there's no response, check for dirt or damage on the sensor and clean it. Next, test whether the power fuse is blown and try replacing it simply. If it still doesn't work, the sensor itself might be faulty or there could be a control module issue, requiring professional diagnosis. I recommend using the reversing camera to assist in judgment—if the camera works fine but the radar is silent, focus on repairing the radar. Don’t neglect daily maintenance of sensor cleanliness, as mud coverage can cause false alarms, especially in rainy weather when issues are more likely. Regular testing twice a year can greatly prevent reversing accidents.
To test if the radar is working properly, I simply start the engine, shift into reverse gear, get out of the car, and move around behind it to see if it beeps. The sound should be rapid when the distance is too close, and weak or absent when too far. If there's no reaction at all, it might be broken or have dirt blocking the sensor—just wipe it off. Alternatively, place a small bucket near the garage wall and slowly reverse to see if the warning light comes on. The first time I tested it, I didn't understand, but later I learned that maintaining a half-meter interval is the normal response. If the radar fails and the sound is strange, I go to the 4S shop, and they check it for free. Don't be lazy—test it before driving every week to detect problems early.
