adaptive cruise control not working

[mossy69]

hi this has happened to me twice now comes up on the center display as error acc took it back to the dealers 3 weeks they sorted it but it has come back on again this evening acc doest work ...is there a quick fix I can do myself as don't really want to go back to the dealers    cheers

[fredgroves]

Does it error every time you start it? Ie from one day to the next? Immediately you turn the key?

[mossy69]

no just when im driving very strange I know any ideas  cheers

[fredgroves]

Is it when you turn acc on? Again, immediately or just randomly? Does it happen in particular places?

[mossy69]

no not really just comes on you have any ideas

[fredgroves]

Sounds like it's maybe a loose connection or fault in the radar unit. Either that or alignment of the radar unit. It's a very precise alignment. You haven't hit anything at all? Rabbit or pheasant or something?

[Don76]

Sorry for thread hijack, but how does lowering your car affect ACC??

OP - if I were you I'd get back to the dealer.

[Bungleaio]

The sensor knows where it is relative to the road, within a tolerance to allow for natural movement and bumps in the road.

If you lower the car the sensor isn't where it thinks it is so it could give false readings hence why it should be recalibrated. Quite a few have lowered without it causing an issue but it can cause problems.

[fredgroves]

I was told that fitting a tow bar could need it recalibrating too

[JoeGTI]

My rear wheel alignment was slightly out in the R recently - it was causing the steering wheel to be slightly off centre when driving straight. Anyway, the VW dealers told me that the re-alignment process also meant that the ACC sensor had to be re-calibrated too. The equipment used to do this alignment is very expensive and some VW dealers don't even have it.
That's all fine and dandy when the car is under warranty... I dread to think what the maintenance of that sensor is likely to cost when these cars are a few years old and out of warranty.