S6 Random fault codes which appear on start up but then dissapear when I restart the car

[S66666666]

Hi, 

Any help/suggestions with this would be much appreciated. I bought an S6 in a private sale a few days ago and since then random fault codes have been appearing when I start the car but then disappear when the car is turned off and then back on again. The first issue was a fault with the start/stop- a message appeared and the car refused to start. I turned the start/stop off and tried again and the car started. I turned the car off and then back on again with start/stop engaged and it was fine with no messages.

The next issue, later the same day, the display showed a fault with adaptive lights- again this code disappeared when I turned the car off and on again. Later the same day,another issue. This time, adaptive cruise was unavailable with the message "ACC and Audi braking guard not available". I turned the car off and back on and this issue also disappeared.

I am booking the car in for a diagnostic check with my local dealership asap but was wondering if anyone has any ideas on what the problem could be? I'm wondering if it could have been caused by out of date software maybe?

I'm also wondering where I stand with the previous owner who assured me that there were no faults when I bought it from him

Thanks everyone for reading this!

 

 

 

 

 

 

[Magnet]

Hello Charlie, 

In my experience, displayed fault lights disappearing on switching off and switching on again is not uncommon. 

Maybe too simplistic, but such fault lights/messages can occur where the battery voltage or efficiency is below par. Appreciating the car is only 5 years old, batteries now have a hard life with stop/start systems and are more likely to suffer shorter service lives. 

Dont quote me! since I’m trying to get my aging brain around these systems, but there could now be two batteries fitted to your car. 

Where you stand with faults with a car bought as a private sale? It all depends on how the car advertisement was worded. If any ( particularly written) reference is made to its overall condition then the vehicle should match that condition. Verbal assurances - obviously more difficult to prove. Condition matching the advertised wording often leads to descriptions such as ‘drives, runs, stops’ , limiting the comeback on private sales. 

Good luck in getting it sorted. 

Kind regards,

Gareth. 

[S66666666]

Hi Gareth, 

Thanks for taking the time to reply and thanks for the suggestion about the battery, It would be great if that resolves the issues. I am kicking myself over the private sale and wording as I had asked the seller if there were any known faults and was going to ask him to write it on the receipt and then, in the moment, managed to forget. 

I will post an update as soon as I know more 

Best wishes 

Charlie

 

 

 

[T-Cut]

Hi,

Take to someone with a VCDS code reader. There may be someone on here who may be able to help. Magnet is correct in saying it could be a low battery with the stop/start, but regarding the cruise and adaptive headlights . I had a simlar problem. I got the camera behind the rearview mirror recalibrated, now all good.

If you was nearer I would have a look for you.

Hope you get it sorted mate

Edited June 25, 2019 by T-Cut

[Jim70]

On ‎6‎/‎15‎/‎2019 at 10:28 PM, Magnet said:

Dont quote me! since I’m trying to get my aging brain around these systems, but there could now be two batteries fitted to your car.

Just to clarify things on the battery.. There is only one battery and it's a big expensive one in the boot 🙈. I had an RAC recovery guy out to my works van and while he there I asked him about my car, whether it had two batteries or what.

Sorry that's probably no help to finding what the problem is though 🙄

 

Hope you get it resolved mate and two fingers to the xxxx that sold it to you probably knew fine there were faults on it.

[Magnet]

You could well be right about only one battery James, but it is now not uncommon for vehicles to have a small (very small) auxiliary battery which can control BCU type signals. Personally, I would want it proved that there is simply one battery ( big and of course guaranteed more expensive via RAC). 

You would expect ‘them’ to know, but recent experience with a non Audi is tending to dispel that fact.

Kind regards,

Gareth.