The rear proximity sensors apparently failed when somebody backed into my rear bumper. The bump was so mild that I was unaware of it. There was no obvious damage to the bumper except for some very small paint scratches on the protruding bumper guard. The Pontiac dealer refused to repair the malfunctioning system stating that it had failed as a result of an "accident" and was therefore the responsibility of my insurance policy! In addition, I later unfortunately backed into a pickup truck with a very high bumper and hitch and dented my rear hatch door. At that time, I thought my rear proximity sensors were still functioning and expected that they would alert me if I backed too close to another car. So now I am expected to file two accident reports with my insurance company! Since I have $500 deductible, this could cost me up to $1000 just because the rear proximity sensors can not withstand a slight bump to my rear bumper. If the proximity sensors are so sensitive to a slight bump, they should not be mounted in the rear bumper. Also, whenever they stop working, there should be a noticeable warning light on the instrument panel.