OK, I'll buy it....what's the secret? I just spent the whole afternoon trying to replace one of my rear back-up sensors. I popped the bad sensor out fairly easily in a few minutes using the 'push and twist' technique and managed not to damage the bayonet notch on the outer trim ring, but.......... damned if I can get the replacement back in!

The whole assembly is in good shape.The trim ring, spring and spring collar all seem fine and the whole assembly slips together very easily off the car, but trying to get it back into the bumper cover is kicking my butt!

There is very little room to work (or see!) and matching up the alignment notches in the trim ring and spring collar while keeping everything compressed and central with the hole in the bumper cover is what's killing me. When removing the sensor the alignment notches didn't effect anything, they just pulled apart, but going back together everything has to be correctly lined up, and it's tough to be in two places at once. So, thought I'd check to see if there's some fiendish trick to the replacement or am I looking at pulling the bumper cover....or hiring a contortionist? Thanks in advance for any inspiration.

 

Success! I finally gave up trying to replace the sensor 'in-situ' and dropped the bumper cover. Wish I'd done it sooner. Only took about 30 mins, and with much improved access and visibility the sensor went in quite easily. The poor access condition only affects the two direct rear-facing sensors as they are recessed inside the rear collision beam while the two corner sensors are out side the collision beam and much more easily reached.

Bumper cover came down very easily and access and visibility to the two centre sensors was massively improved.

Back of the installed rear facing sensor buried in the collision beam. I was able to remove it with the bumper cover in place but evidently I lacked the dexterity to maneuver it back in!

Success.