My front right pdc sensor isn't clicking. Long beep when I go into reverse. Looked at it tonight, can't see how to replace it.. Looks like I need to take bumper off... Please tell me that I am wrong?,!

Pup

Another possibility, I wiggled the wires on each rear pdc the other night and all was well pdc worked, until I drove it the next day.. I suspect a loose or dirty connection... All are clicking except front right...

Where to start?

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Pup
2006 BMW X5 4.4i Sport Package 105k miles Imola Red
2000 Porsche 986S. Boxster S 50k miles Silver with Black leather, convertable, and Factory hardtop
2015 Mini Cooper S 4 door, Blazing Red Metallic, white roof and mirrors, black leather, cold climate pkg, Sport Pkg