My blind spot assist is shaky at best. Sometimes the light doesn't turn on, other times it does turn on but doesn't beep. The dealer noticed a very light scrape on the rear right bumper and said that could have caused the sensor to be knocked off, even though it's the left side blind spot assist that doesn't work well. I find it hard to believe that a scrape (no dent) could have knocked a sensor loose. Does anyone have the installation location and/or rear bumper diagram for this vehicle? Also, the CEL is not on and it's not throwing any codes.

 

If it were related to the scratch, I'm sure your car would have already shown errors.