clicking parking sensors

I’ve read on several threads over the past couple of years that you can identify which failed parking sensor has filaed by listening to them in turn, to see which one isn’t clicking.

I’ve got exactly the same symptom (endless squealing) as I’ve had twice before when sensors have failed. However, all four sensors are clicking when I listen to them...

So, although the symptom is exactly the same as previously – is this likely to be something other than a faulty sensor? (not tried changing each one in turn yet – too wet/dark by the time I get in)

cheers

Edited 17 March, 201115 yr by sidewaze samm