A4 Aerial lead

[Drizz]

Does the A4 have a little aerial adaptor with a white wire coming out of it??

 

[AndyMac]

No the stock HU unit doesn't, but it may have had an aftermarket HU previously which needs the adapter in order to power the aerial amp. The white wire should be connected to a remote on or power antenna feed, if it looks like this:
http://www.caraudiodirect.co.uk/aerial-adaptor-p-211.html

 

[Drizz]

Spot on cheers Mac...