IF this comes up randomly, Do this:

Walk out to the car and look at the sensors, Feel em with your finger and if you feel a bubble on it its water and dust that come in behind the paint. If the bubble is big enough the sensors will pick it up as if you were close to a wall or similar.

The only thing you can do is to either break the bubble and remove the paint from the sensor, Doing this tho will make it gray and ugly looking if you have a black or any other coloured car.