this will stump you

[PeteGPhil]

this is a very challenging one - I have a 2013 A6 Avant SE 2.0l TDI.  I have for some time had a strange electrical problem which means I loose most of the driver assist functions. (stability control, tyre pressure monitor, hill start assist)  at first it seemed to be linked to water/damp, but over time has become more frequent.  It would occur at various times, whilst driving, when starting up and originally about once every couple of months, although now it is weekly.

Yesterday was a clear example (it was very hot) - I left home about 9.00 and drove just over 50 miles, it was perfect.  I stopped for about an hour, when i started up to go I got error messages about all the above plus brake system error, and no power steering, the engine management light was also flashing and the auto handbrake off didn't work (often during these periods when applying the handbrake I get "vehicle parked too steep"), and also no aircon.  I drove about 20 minutes to my next destination, parked up for several hours.  Got back in the car to return home - same issues again, then after a few minutes power steering came back, aircon started working and engine management light gone.  I drove about 30 mins and stopped for 5 minutes, switch on to finish journey - everything cleared except hill start not available.

Some other facts - sometimes but not always the faults clear when restarting, they rarely clear whilst driving.  The computer (diagnostics) has said no faults, but that was when none were showing but also none in the history.  a few days previously the faults had appeared during a 5 mile journey.

SO any ideas where to start to look - it seems to me to be linked to items managed via the centre console area (Stabilisation control, stop start, hill start etc) but I am wondering if there is a module that controls all these functions or is at least a link between them.  Thanks

[Magnet]

Simple thing to eliminate/incriminate first - age and serviceability of battery?

Kind regards,

Gareth. 

[Magnet]

Hello Peter,

Notice you’ve returned to view the response to your question. Was the reply any help to you - or perhaps not? 
Kind regards,

Gareth. 

[treeshake]

21 hours ago, Magnet said:

Simple thing to eliminate/incriminate first - age and serviceability of battery?

Kind regards,

Gareth. 

The battery would be my first suggestion too.

We had a similar issue with our A3, all the driver assist faults went away with a new battery.

[Magnet]

Thanks Mark, but our original poster seems to have gone to ground. Shame isn’t it, when a reply is looked at, but zilch response. 
I’m terming it ‘post and run’! 
Kind regards,

Gareth. 
 

[PeteGPhil]

Hi both

 

thanks for the responses, it is certainly something I hadnt considered.  The battery always seemed fine absolutely no problem starting etc etc ,but it is as far as I am aware the original and as you say a relatively easy thing to eliminate.  I will look at doing that and see what happens

[gsmdo]

Battery would have been my first thought - and starter motor would have been my second. I had a raft of problems with a failing starter on a BMW motorcycle, that were completely illogical at the time.

Please drop back in and update us on the solution when you find it. 👍

Mike 😎

[PeteGPhil]

Hi both

So new battery is on, only time will tell now, sometimes I have had to wait a month or so before seeing the errors, hopefully I wont see them again.  I will update the thread from time to time.

I am a bit old school so for me I only changed the battery when the car wouldnt start - but modern electronics are so different.

 

 

[Magnet]

Thanks Peter,

Has the new battery been coded to the car? Make of new battery out of interest? 
Kind regards,

Gareth. 
p.s. Think I would have had a ‘sophisticated’ test on it first, but…..

[PeteGPhil]

I opted for a halfords battery for now as not sure how long I will hang on to it, and yes coded to the car.

Over time two different garages have looked at it, Audi main dealership had it for 4 days, test drives computer, the works they could find anything (no faults came up whilst they had it either) and a local independent Audi dealer also had a good look at it another time same result.

if the battery doesnt work I am probably going to have to wait for it to die or the fault becoming more frequent before being able to track it down

[PeteGPhil]

Ok so it wasnt the battery - been out twice since its been replaced and both times error messages and dash lights have come up.

[evopilot]

was it an AGM battery and did Halfords code this battery to your car?

[PeteGPhil]

not sure the make but yes it was coded.  things have gone quiet again at present, all working OK but it did that before so could be ok for a month or so and then problems start again.  Only time will tell

[BlackAudi]

Hi,

I had the same issues on my A6 C7.5 and it wouldn’t stop popping up now and then.

These Christmas lights only comes on turning full right and OBD 11 scans shows consistent right wheel speed sensor and open circuit.

Vartar AGM Battery, 2 wheel speed sensor Bosch / Original Vag, wheel hub/ bearings, Audi factory reflash but no avail.

Workshops also run out of ideas. My final guess is the wheel speed harness but we don’t see any bad wiring undercarriage.

[Stevey Y]

6 hours ago, BlackAudi said:

Hi,

I had the same issues on my A6 C7.5 and it wouldn’t stop popping up now and then.

These Christmas lights only comes on turning full right and OBD 11 scans shows consistent right wheel speed sensor and open circuit.

Vartar AGM Battery, 2 wheel speed sensor Bosch / Original Vag, wheel hub/ bearings, Audi factory reflash but no avail.

Workshops also run out of ideas. My final guess is the wheel speed harness but we don’t see any bad wiring undercarriage.

 

Hi have you chased the wheel sensors wiring up behind the arch liners thats where it normally goes as its nice and damp under there with loads of dirt.

Steve.