Hi all.  After some advice.  For the last 2 winters i have taken a weeks holiday and left my 2008 A6 standing on the drive.  Upon returning, my rear demister has stopped working and exactly 10 minutes into every journey the ESP warning light has come on (see owners manual) and stays on until engine is next turned off.  Around March/ April the battery warning light has come on and the faults have reset themselves and been fine until December!  I assumed this was due to an old battery (nearly 10 years).  However, I have had the battery replaced today and the fault still remains.  I wondered if anyone had any suggestions before the dreaded dealership diagnosis....

Poor battery can cause all kind of faults. Usualy after battery replacment the esp fault goes away after driving for few miles 

Also unless you replaced batter loke for like it need to be coded 

And it could be that the esp fault needs to cleared using vcds/carista/local garage...

 

Thanks. It wasn’t like for like so will ask garage today if they coded it. 

I have exactly the same problem now with my A6. ESP fault after exactly 10 minutes of every journey and rear dimister doesn’t work. This all occurred after the battery warning light came on while driving. Required alternator replacement. 

Hello Gavin,

My advice would be to first have the alternator output checked - yes I know it has been replaced, but replaced does not always equal fully serviceable. Well worth confirming the output value. 

Other port-of-call check would be checking the battery condition and serviceability. 

HRW not working? Worth checking the above first, before moving on to diagnose the cause.

Kind regards,

Gareth.