I have noticed a few times when stopping at a set of lights that the cars beeps steady. One time it was happening constantly and I found ice forming on the sensors so I took her for a wash and it stopped. Could it be that the vehicle in front or behind is to close or could it be something different altogether?

 

If its raining mine beeps all the time when I stop, and occasionally when it is dry, particualrly if I am next to a Harley! Very annoying, wish I could reduce the sensitivity. It appears to be only the front park control sensors that do it on mine.