My parking system is failing. When going in reverse or manually hitting the parking system button, I have the camera screen come up, get a long beep, and then it goes back to the previous screen (radio or whatever was on). The parking system button light keeps flashing.

There are plenty of threads that describe the cause as a faulty sensor, so with ignition on and gear in reverse, I put my my ear on each sensor (4 front, 4 rear), and all of them click.

Could it be that despite the clicking one sensor is faulty, or could it be something else ? Don't have access to Vag-Com at this time, unfortunately.