I was rear ended recently and had to have the rear bumper replaced. The body shop replaced it with an OEM bumper from the dealership parts warehouse. The issue is with the parking sensors/cross traffic alert sensors. The openings in the bumper, where the sensors butt up against, seem slightly larger than the originals. There is a small gap around the sensor's gasket/o-ring, where it sits in the openings, a noticeably larger gap than the originals. My local Toyota repair center could not give me answers on why that would be. They are not the ones who did the work, but I figured they would have experience in that area, and have a possible answer or solution, but they didn't. I don't believe the gasket is supposed to be water tight, to keep moisture or dirt,from getting around it, but the Toyota people could not answer that either. Any thoughts? I'd like to fill the gap somehow if I could

 

Pictures?
Are you sure its a Toyota bumper?

 

Here are a few pictures of several sensors

 

The sensor is a self contained unit. The o'ring adds a joint/buffer between the sensor and bumper.

May be able to find wider (thicker) o'rings of the same ID which would fill the gap.

Could get high quality black silicone. Then using a narrow tip applicator run a bead around to fill the gap. Tape off he areas you don't want the sealant to be applied.

Given the pictures, doubt the body shop will do anything more.