Lets back up a little. This sat it was working again i wipe clean the sensor and it work fir the whole day.. i thought i fix the problem. But after washing my x5 sunday did not work again. Did the check and it is the left rear sensor on the rear bumper. (BY THE WAY YOU CAN HEAR AND FEEL THE SENSOR CLICKING)

So what now. It could be a bad connection or bad sensor either way I have to get to it and remove it. Any one have the procedure. Any one knows how much a sensor cost. Thanks