Thanks for your help with this. I wonder if since the lights didn't move when I moved the sensor arm, that the rear sensor was damaged in the accident. It took a pretty good lick to the lower A arm which this is attached to and may have tweaked it enough to mess something up. With the high price of these sensors, it's a rather costly guess to see if it's the problem, but who knows, I may have to make that leap. I love the car but have been a little suprised at the price of parts, and the gas mileage.