Numerous faults

[Paul cairney]

Can anyone tell me what this box is its in the boot next to battery boot had some water in it rook to halfords for battery health check and its at 93% and is charging ok so not battery that is problem thanks in advance

[Stevey Y]

1 hour ago, Paul cairney said:

Can anyone tell me what this box is its in the boot next to battery boot had some water in it rook to halfords for battery health check and its at 93% and is charging ok so not battery that is problem thanks in advance

Hi I think thats a voltage stabiliser module, nothing in the boot enjoys water.

Steve.

[Anton8]

You are quite right Steve. It is a voltage stabiliser module. ( Checked part number online)

[Stevey Y]

44 minutes ago, Anton8 said:

You are quite right Steve. It is a voltage stabiliser module. ( Checked part number online)

Hi Tony, can you expand on the multiple faults you titled this post with ?.

Steve.

[Paul cairney]

[Anton8]

Hi Steve. I think you mean Paul

[Magnet]

Hello Paul, 

As I’ve said before, and I think as Steve has confirmed- Halfords battery testing may not be totally adequate in terms of assessing all of the parameters which assesses the total efficiency of the battery. I have certainly confirmed  that with a just-out-of-warranty non-Audi. 
You could find that genuine VAG diagnostics may pick up some issue with the battery in some respect - say for example cold cranking current below par. 
I appreciate VAG diagnostics can be expensive, (independent?) but I would be asking, are you prepared to pay to replace any number of components before firmly establishing that these issues aren’t battery associated? 
Kind regards,

Gareth. 

[Stevey Y]

4 hours ago, Anton8 said:

Hi Steve. I think you mean Paul

Hi a thousand apologies, thats what comes off the back of a large roast dinner and not paying attention.

Steve.

[Stevey Y]

14 hours ago, Paul cairney said:

Hi I hate to say this but these are ALL classic symptoms of a failing battery, I don't know how old your old battery is but if it was not readapted to the car when fitted it will fail in record time, do you have access to any diagnostics as I am sure these lights are communication fault caused by inconsistent battery voltage, in the old days a car could run on a knackered battery mostly on whatever the alternator puts out but later vehicles won't as the alternator currents always fluctuating.

I would start in the boot and check all the wiring and plugs that were anywhere near that water the easiest way to check would be connect the car to a slave battery and run the car on and off a few times to see if any of the lights disappear but TBH plugging in is really the only definitive answer.

Steve.

[silvester]

Hi hawe same problem how did you solve the problem

[Marko KLC]

On 2/27/2024 at 4:35 AM, jasonj said:

Hi Silvester ,

1: Have you got the same warning lights on the dash ?

2: Do you have water ingress in the Control  Voltage Stabiliser ? Jasonj

I’m getting these Kremlin’s as well.. with OBD11 only actual faulty item other than generator problem was front right speed senso (A6 C7 year model 2011)… same time TPMS, ACC, parking break and other fault codes. Speed sensor I did change, same problem came back, now being evaluating this as multiple alarms and fault codes seems to go away or can be reset if I will plug charger to battery.. Car alternator was replaced by Plus Huolto Turku, Finland 2 years ago… I noticed that they did used some probably cheap reconditioned unit for this.. (don’t ever use this service, with few other things needed to be done end up doing same myself.. takes time but all so far are now working.. I will check the regulator matter next… 

[Marko KLC]

Seems to be water related issue, moisture inside car quite high… 

[Marko KLC]

I done more excavations etc.. BCM module dry.. Checked J533 module under backseat, used oxide clean spray for connectors.. and dried it with compressed air... All these codes are more related to matter there isn't communication between the modules.. Makes me thinking how the earthing(grounding) is done for all of these components... I tested today the battery 90% of brand new.. Same time getting error U105200 which also relates to communication.. Mainly all issues as I have checked are not the components the problems seems to come from but intermittent etc.. Does anyone have some sort of picture or graph that would identify locations where earthing cables are in the chassis.. Probably the actual problem isn't that big one, but after reading this forum a bit, noticed that who ever solves the problem disappears faster than diarrhea 😞

I'm greatful if anyone has more wisdom for this matter..

Attached txt file, OBD11 scan for the issues....

Br,

Marko

 

A6C7-hassle.txt

[Jonny G]

I’m having the same issues with my A6 C7 Allroad. Multiple faults and warning lights. I recharged the battery, which seemed to cure the issue for a while, but when it came back I decided to replace the battery as it was 6 years old.

However, a 2 months on and the problem has returned. New battery, all coded to the car and installed, and one cold morning the issues have returned.

Interesting to hear that it could be related to moisture in the car as I recently noticed that the panoramic roof had been leaking (in the common way that they do!) but I’d solved this. I wonder if the battery issue is due to residual moisture still in the car? I did notice moisture under the spare wheel.

 

[Magnet]

Welcome John,

Alternator output checked before moving on to more complex reasons? 
Kind regards,

Gareth. 

[Jonny G]

Thanks Gareth.
I haven’t actually check the alternator, I’d assumed due to the age and low mileage that the alternator would have been ok, but I will now check it out. 
The large number of totally unrelated faults, ESC, air suspension, brake servo, electric parking brake, ABS, high beam assist, and more all seemed to point to the low voltage problem, and as the battery was still the original I thought (hoped) changing it would be the end of the problem but no, it’s back.

I’ll post once checked.

 

 

 

[Magnet]

Thanks John,

My thinking was based on ‘..recharged (old battery) issue went away ….’ replaced battery …. cleared…2 months on the problem has returned’. 
Simple test to get a verdict on the alternator, so worth checking. 
Make of new battery by the way John - ? 
If the alternator tests OK, it might be worth checking for a parasitic drain. 
Kind regards,

Gareth. 

[Jonny G]

The new battery is a Varta (as was the old). I checked and made sure I was getting the OEM replacement. 
 

I’ll check the alternator. The car has only done 56k miles, the alternator should last longer than that shouldn’t it? I though they normally last 80k to 100k?

[Magnet]

Should be all good on the Varta front John. 
Was it coded to the car? 
Whereas it would be reasonable to assume that the alternator is perfectly serviceable, it can only be an assumption until proved to be so, so on a one thing at a time principle, it would now be well worth getting it checked - and hopefully eliminated as an aggravator. 
Kind regards,

Gareth. 

[Jonny G]

Post update. 
 

I tested the alternator yesterday.

With the engine off the voltage on the battery (new) was 12.5v, then on starting the voltage dips but at 2,000rpm and above the voltage increase to 13.6v. Not as high as I thought it would be but that does suggest it is charging the battery.

I checked the belt to see if it was worn or loose, but it seems good, no visible signs of damage or wear, and it was tight.

Put the battery on the trickle charger overnight and the warning lights were not there this morning. 
I guess the next thing would be parasitic drain. I unplugged the only 2 accessories in the car when I parked and turned the car off,  the Nextbase dashcam and the quadlock phone charger. Hopefully this will solve the issue.

Do you think repeatedly only doing short journeys, and driving in economy mode where rpm is always low contribute to the issue?

I’ve had the car from new and this problem only surfaced in December 23.

[Magnet]

Thanks John,

13.6v output from the alternator is certainly too low - I would be looking for around 14.5v.

Personally, I would put a possible parasitic drain second on the list, and concentrate on getting the alternator/charging system professionally assessed. I would consider getting yours repaired rather than fitting an aftermarket replacement. 
Seems it’s time for an auto electrician. 
Perhaps you would let us know how you get on.

Kind regards,

Gareth.

[Jonny G]

Like others on the thread, I’m beginning to think that this is all due to moisture. On further investigation, I found that the carpet in the boot was soaking, as was the boot floor. Stripped it all out and dried everything off in the sun.

I’ve sealed all the rubber plugs and dried the Voltage stabiliser unit. I’m hoping that this will solve the problem.

 

[Jonny G]

My joy has been short lived. 
 

The car is fine when driving in the dry, but today in the rain, all the faults have returned. 

I spent an age trying to seal any and all holes in the spare wheel compartment of the car where I keep finding moisture, but I keep finding moisture in the bottom and a damp patch on the carpet, drivers side under the spare wheel, below the Bose sub woofer.
 

Does anyone else have any suggestions?

 

[Magnet]

Hello John,

Have you read the more recent thread - ‘Most warning lights on’?
Kind regards,

Gareth.

[Jonny G]

Thanks yes, saw that thread. It seems a common issue with the C7, they like to let water in as much as possible.

Further investigation this evening and I narrowed down the leak. See the picture attached, but the leak is coming through a seam in the side wall. Circled the area in red.

I have sealed this area with Gorilla waterproof patch & seal tape.

I removed the Voltage stabiliser unit to dry it out, and also moved the wiring loom for the Voltage Stabiliser unit up and back out of the spare wheel well up into the area where the main fuse board unit is. 

I hope that these two actions will cure the problem.