I got in my car today, after my brother had borrowed it for a few days. When I put it in reverse the sensor goes nuts, with nothing behind my car. Any ideas. My brother has assure me he didn't hit anything.

 

faze, with the help of a second person, put the car into reverse and then place your ear next to each of the 4 sensors. The one that isn't making a sound (quiet high pitch squeal) is a bad sensor. I am assuming you are hearing a constant 3 second tone with nothing afterwards.

 

Or, there maybe some gunk on the sensors, not sure though. i'd go with thermo

 

Well when I put my car into reverse today, it didn't do it, it has been raining the past two days, so maybe it was "gunk"> Where exactly are the sensors located btw?

 

faze, stand behind the car, look at the black plastic piece where the exhaust exits. One the outside corners and just inboard of the exhaust pipes, you will see some small black circles. Those circles are your back up sensors.