Audi A6 is behaving erratically, could it be the electronics?

Hello community,

My friend's Audi A6 Avant Quattro, 3.0 Ltr., 180KW, manufactured in 04/2012, is having major problems.
I read him out on 25.08.16 after he had turned on all the lights and indicators in the cockpit during the return journey from the shops (approximately 20km).
The measurement was taken approximately 1 hour after arriving home on the same day.

In the appendix, you can view a 33-page error list, which contains approximately 80 error messages.

It seems like there was a temporary interruption in the main power supply, or a main power source.
However, the Audi was functioning perfectly, with no malfunctions in any of its systems. Only all the lights and lamps turned on one after another, including the "engine control unit" and "gear control" systems, indicating a "locked" status. Despite this, he successfully completed the specified route.
How do I do that???

I'm really looking forward to hearing your opinions, because I don't know where to start looking, I'm completely overwhelmed by all the errors.

Thank you for reading and have fun troubleshooting.
If further data is needed, please post it, and I will try to obtain it.

Currently, it's not starting, allegedly due to a low battery.

Hi
Michi

Quote:

Currently, it's not starting anymore, allegedly the battery is dead.

With this, the error should already be found. If control units are operating at low voltage, they may report errors, sometimes even quite nonsensical ones.

I spent several days testing with VCDS on my wife's Golf. The battery in it was already old (original, from 2008)) and was probably a bit weak. Suddenly, I had dozens of errors in the log, even though the car had just come from the workshop. Plug in the charger, it charged, and then I drove around the block and everything was fine.

I would first check the battery, and if necessary, replace it or at least charge it.

And what I learned: Intensive use of VCDS only with a charger.

Hi,

Immediately, two things come to mind:
- Cable connection: loose or firm?
- CAN drive, short circuit. That's all that's left: to measure the wires and pay attention to the areas where there are problems.
- "Only" the battery being weak would be possible, but then there would be error entries regarding undervoltage and not...

Quote:

...Voltage Terminal 30: 14.5 V Voltage Terminal 15: 14.5 V...

under the error boundary conditions.

Best regards, Rainer

@ Virus:
The battery was fully charged at the time of the car scan.
That can't be right, but still, okay.

@ Rainer:
CAN-powered, Short circuit.
Question: Where is the CAN controller located, what does it look like, and can I perhaps find it in the RLF (Racing Line Feature) of Audi?
Sorry Rainer, CanBus are for me "Bömische Dörfer", meaning something I don't really understand.
Maybe you could describe the process with VCDS to me, how I can get to where I need to be through which channel and check the CAN, or something like that.
When faced with a lengthy list of errors, I'm unsure where to begin.
Absolutely, but first, charge the battery and then continue watching.

By the way: After the reading, I had deleted all the errors. After that, however, they all reappeared.
The following attempt was successful. The engine ran normally, but I had not actually started it, and the Christmas tree in the cockpit was missing. Everything is normal, but the errors are still there.
Hi
Michi

Hi,

The CAN controller connects all the control units in the powertrain. Interestingly, diagnostics also pass through it (OBD2 port -> Gateway control unit -> CAN controller, CAN comfort etc.), meaning that if the fault is in the CAN controller, no diagnostics will be possible on the affected control units. When it comes to the CAN bus, there are 2 wires, CAN-High and CAN-Low, see: http://www.obd.wiki/can

I am concerned that, in addition to the visual inspection of all relevant cable bundles, a wiring diagram for your vehicle is recommended. Has anything recently been modified on the vehicle, such as a screw being inserted somewhere? Was wurde am Motorsteuergerät verändert?

Step 0: Are the battery terminals securely attached here?
Step 1: First, delete all the errors and see which ones reappear.
Step 2: If no further CAN errors occur after Step 1, temporarily move the wiring harness to different locations and check if any errors occur in each location.

Probably not necessary for troubleshooting, but if anyone is interested in learning about the CAN bus:
http://www.canhack.de/viewtopic.php?t=13

Best regards, Rainer

Quote:

Step 1: First, delete all the errors and see which ones reappear.

Especially, pay attention to the timing and the order in which they reappear. On the CAN controller, there was a nonsensical date at the top.
Maybe the first few minutes of operation will be sufficient?
hg
Herbert

Basically, no one has messed with the Audi. Last year, I had a trailer hitch installed and the corresponding control unit registered and coded for "Fixed Hitch". Maybe you remember, Rainer.
I also posted a request about this here, and we also communicated about it to find a solution.
Since then, the Audi has been running perfectly, and no one has made any adjustments to it.
I don't know how this happened, with so many errors.
It just suddenly appeared.
If I find out anything new, I'll let you know here.
Thanks both for the tips.
Hi
Michi

Hello Michi,

Do you already know what happened to the Audi A6 back then?

I'm currently experiencing the same problem with my A6...

lg
Peter

Yes, Peter,
I now know.
The A6 continued to run without problems for about 14 months, but occasionally the Christmas tree indicator would appear in the instrument panel.

In January 2018, he then went to the Audi workshop.
Diagnosis: Defective PCB or chip in the gear control unit.
It has been replaced and is now running perfectly, without any issues or pine trees. But it still cost a little over 1000 euros.
In addition, a free update was provided due to the previous diesel scandal.
Since then, I haven't been able to schedule a service or inspection anymore. Oelservice reset function is accessible via the large display in the center console.

I don't know why service/inspection resets are no longer possible. This is really annoying, because every time I start it, the message "Service due" appears.
Maybe someone here knows if, using VCDS, I can't get the service reset or returned, even though it's already been done and the next one is coming up soon.

Hi
Michi

Ok, vielen Dank für die Info!

lg
Peter

amishorty wrote:

I don't know why service/inspection resets are no longer possible. This is really annoying, because every time I start it, the message "Service due" appears. Maybe someone here knows something about it. With VCDS, I can't get the service to be deleted or reset, even though it has already been done and the next one is coming up soon.

Hi,

should work perfectly. First, determine whether you need a fixed or flexible schedule, and then select the appropriate channels.

If you take a Screenshot of the available channels (dropdown), you should be able to find the correct ones.

Hi, Rainer