For those who get false alarms like crazy with nobody near. When you get out of the car, give the sensor approx 7-10 seconds before arming! This allows the sensor to take average measurements to compare to when it is armed! If you arm it too fast, it's comparing measurements to when the door was open, and now that the door is closed, it will chirp randomly and frequently! After figuring this out, it is WAY more reliable!! Now the only false alarm I get is when I lock the car, then it starts raining. The rain will sit on the windows and trigger the ultrasonic sensor that the distances to objects has changed. There's no way around this other than dumping the sensitivity to where the sensor is useless.. the answer? Putting a toggle switch on the signal wire to the alarm so if you know it will rain that night, you can disable the sensor without unplugging it.Sensor is RAD.. helps like crazy when living. In the bay area, San Jose CA.. had cars stolen in the past.. now I've caught thieves trying to steal my 240sx! Pair this with a dash cam that records on motion and a 2 way alarm that can send you alerts... Awesome.