andonevris

Hi Guys, new member here was wondering if anyone could shed some light on an issue I have.

As the title suggests I have got the dreaded ACC and Audi Braking Guard: Unavailable error message on my 2012 S8. I have read through the forums and general consensus seems to be some sensor malfunction or ACC alignment.

What complicates the matter for me is I had the windscreen changed yesterday and the fault happened today so I'm wondering if it's related or just a coincidence. I don't think the windscreen guy replaced the rear view mirror correctly as the windscreen wipers will now just fire off randomly with no water on the screen, so definitely something off there and I know the wiper sensors are in the back of the mirror.

I called the company that replaced the windscreen to complain and they proceeded to feed me some BS about the ACC being linked to the odometer and nothing to do with the windscreen but there are a load of sensors on the back of the rear view mirror and the timing of the fault seems suspicious to me.

I took the car to a mechanic friend who pulled up a vague error code under the distance measuring category which unfortunately didn't shed much light on the matter.

Does anyone know if the rear view mirror has sensors that are used by ACC or alternatively any ideas as to how a windscreen change could affect ACC and braking guard.

Any info would be greatly appreciated.

andonevris

BTW here is the error code we pulled

U111300 Function limitation due to received malfunction value

Thanks for that Audi

derfA8L

Pretty sure there are a number of things that have to be re-adjusted when windshield is replaced. The rear view mirror camera handles the active lane assist function, which might in some way be affecting the ACC failure...but I'm just guessing here. Best thing is to have a dealer hook the car up for diagnostics and possible adjustments/re-coding.

BTW, why did you have to change out the windshield? Did anything happen that could have affected the alignment of the ACC sensors in the lower front bumper assembly?

andonevris

Thanks for the reply

I had a stone hit to the windscreen which caused a pretty big crack so got it swapped out by my insurance, problem is they wouldn't let me take it to Audi to do it and I was skeptical about letting a 3rd party do it. There was no damage to the bumper just a single hit to the windscreen.

Next step is to take it to Audi but the windscreen replacement guys assured me they do Audi, BMW Porsche etc. all the time and knew what they were doing.

Car is out of warranty now so it would be nice to get some proof that they messed up so I can get a reimbursement from them for any charges that Audi raise for the job.

derfA8L

BTW, is the ACC failure warning consistent, or does it go away, and then come back on after a while? Also, try running the active lane assist on a highway, and see if you get a failure message on that.

andonevris

ACC failure is constant and the fault couldn't be cleared when we tried.

I don't have active lane assist or traffic sign recognition, there is something that looks like a camera on the rear view mirror so I'm guessing it's for ACC or perhaps the headlight beam adjustment?

frybear

i had no idea that there were sensors in the rear view mirror for the ACC and/or lane departure. I thought those sensors are where the fog lights would go in the lower bumper.

derfA8L

If you are in the U.S. and have ACC, then you also have Active Lane Assist and Lane Change Assist. All 3 were part of the same package. You do have the Lane Change warning lights in your side mirrors, correct? Look at the end of your turn signal stalk---there should be a button at the end of it that activates the Active Lane Assist. There will also be a setting in MMI that lets you adjust the range of the steering wheel vibration that alerts you that you're moving out of your lane. The camera in the rear view mirror is for the Active Lane Assist (read your Owner's Manual).

If not a U.S. spec car, then...Never mind.

andonevris

Yeah sorry should have mentioned it's a UK car.

I know the radar domes are to do with ACC (where the fog lights used to go) just trying to figure out what part the rear view mirror plays in the equation.

There seems to be conflicting info about it's part in ACC. All I know is ACC was fine before the screen change and failed straight after.

derfA8L

I don't think it does directly, but it might have had some sort of sequential impact on the ACC system. In any event, I don't believe in coincidences, and something is amiss that likely does have to do with the windscreen change out. You might have to bite the bullet and take it to an Audi dealer to get it sorted out.