Parking sensor problem
 

Now, I've had parking sensors go before, and replaced the control box, but this is a bit odd.

When starting from cold, the front sensors beep continually (each beep lasting2 or 3 seconds or more) with short gaps between the longer beeps. Once the car is fully warmed up, they work normally.

There are no VCDS fault codes and the green light on the switch doesn't flash (IIRC, it does when one of the sensors is faulty).

Any ideas?

sounds to me like you may have some condensation (or dirt) occurring between the sensor and the paint layer or getting down the sides of the sensor(s) - so the detection is working but its trying to suggest you're about to hit something!
The only solution i guess would be to replace the sensor in question with a newly sprayed one or try to clean out what's there or take the sensor out and clean / respray it ?

But I don't know which sensor it is! :(

Not a job for before the meet if I have to take them all out - too busy with polishing, leather renovating, headlight lens cleaning and carpet shampooing!

I gave mine a quick wash and polish yesterday, but we've got a week in the rainy/muddy Lake District now, walking etc. so it will look like a refuse tip when I arrive in Wales directly from there! :o

vagcom (or whatever variant you have) will tell you which one it is Jim

Read the first post! :) - there are no fault codes

I think he meant to check measuring blocks with VCDS, it will show the readings from individual sensors, the odd one must be faulty.

OK, I can do a scan with VCDS and I've even managed to recode with it to allow the use of the radio clock.

But I have no idea how to check the measuring blocks!

Have a look here: http://forum.a8parts.co.uk/showthread.php?t=5000

Thanks Ainars, much obliged +++

Just need to call David to get a hold of our shared VCDS.