Another parking sensor problem

[b20wht]

When I select reverse I get a beeping from the front sensors,  this happens about 8 out of 10 times and sometimes stops while I'm still in reverse and sometimes continues until I select anther gear.  I have listens for the sensors clicking which they all appear to do, but when I stand in front of the 2 front left sensors they don't make a beeping in the car, so does this mean they are both at fault (even though they both click) or is there another issue?

[moar]

I would connect INPA. It will tell you exactly which sensors are at fault and then you just replace them yourself.

Quite a straightforward job.