quick update on this. All solved!
Fitted the new eBay Sat Nav aerial and it's completely resolved!
The glove box is really easy to remove. Three screws at the top, and two at the bottom and the whole thing drops out. Dead easy DIY.
For the placement of the aerial, in my A6 I placed...
Thanks for that! I've just bought that aerial and will give it a go!!
Do I really need to remove the glove box?? Is that hard?
Stereo unit itself (nav unit) I can remove easily enough,, but never removed the glove box before!!
Also, will it get a good enough signal under the dash? I...
Bit of an odd one...
In our 2005 A6 C5 Avant Final Edition the Sat Nav has thrown a wobbly!
Basically, it seems to operate ok, but it seems to think I'm around 50 miles from where I actually am!!!
You can see it trying to direct me, but of course it's directing from a different...
I think the ABS fault automatically sends the car into limp home mode - which would be your drop in power and acceleration.
Yes, I'd personally get it on diagnostics as likely to be an electrical bug rather than physical, and even if physical then diagnostics should pin point it.