B7 RS4 - Rear Bumper + Parking Sensors

When re-installing, make sure to inspect metal underside mating surface of rear quarter panel to bumper for any debris, rust or chipping. The slightest force can cause the paint to chip in these cases. Clean with alcohol and apply light film of WD-40 or liquid wrench super lubricant for smoother install.
For parking sensors, place metal end of screw driver on parking sensor (you can put a towel between paint and screwdriver, but this will distort a bit). Place plastic handle end against tragus of your outer ear and listen for a difference in sound
For loose heat shields, it's best not to do any sanding before applying JB weld, but you car must be garage queen clean underneath. The paint and shield will bond with no sanding in those cases. If you have some surface rust in that area as in my case, sand as light as possible, in the smallest area, maximum grit of 600, try 1000 first. Apply JB weld blobs in a larger diameter, past perimeter of sanded area to prevent corrosion of exposed sanded area.
Similar procedures apply to b7 a4 rear bumper removal and b6 a4 rear bumper removal