Parking sensors - bleeeeeep?

[clonmult]

'01 A6 Avant TDi - got the rear parking sensors, and they've started to play up a bit. Well, a lot.

They either do nothing (fine, I can still reverse) or just beep continuously (irritating, son reckons it sounds like the car has had a heart attack).

Whats most likely - faulty sensors, wiring, etc? Guess I'll have to pop them out and see if there are any bad connections?

[blueg33]

My 07 A6 has this problem, so far dealer has failed to fix it! Its going back in under warranty