Audi A8 (2019) - Electric Fault, then Drive System Malfunction and loss of power

[BRobertson]

When I was driving today an electrical fault popped up showing a yellow icon of the battery.   After another few miles, a red warning light Drive System Malfunction popped up and the car lost all power.  I immediately turned off the engine and restarted it.  It started fine but after I drove about 10 yards the drive system malfunction kicked in again and lost power.  This happened a couple of times.   I eventually managed to crawl it (keeping under 10mph) to a safe place to stop. Does anyone have any ideas what the cause is?

[Magnet]

Worth getting the battery efficiency checked, together with the alternator output, as a process of cost effective elimination.

Kind regards,

Gareth. 

[Steve Q]

I'd recommend a diagnostic check to see if any fault codes flag up. If you take it to Audi I'd expect to see some form of good will on the repair despite being out of warranty 

[MikeSwidz]

I too have a 2019 A8 TDI and have experienced exactly that same fault - yesterday. Initially the YELLOW "Electrical Fault" came up, then within a few minutes a cascade of other warnings about other driver related facilities becoming unavailable and eventually the RED warning light instructing me to pull over and stop. I duly did and the vehicle totally shut-off. Even the central locking had packed in and I was not able to get out of the car. I tried to restart the engine and just had a rapid clicking response. The entire system was dead. Like you after waiting a few minutes the car display kicked in and I was able to restart the engine - however I did not attempt to drive off as I was about to hit the M25 and I did not want to breakdown there !!! The AA eventually recovered the vehicle and delivered it to my local Audi Garage. They are puzzled as the diagnostics did not flag anything up. There next course of action is to do a system software update - await an update.

I did not expect something like this to occur on an Audi A8. A bit scary as I frequently take the car for European holiday tours. Last thing I want is something like this to happen whilst abroad.

Watch this space for any updates.

[Magnet]

Welcome to the Audi Owners Club !

Good to have you onboard.

Hello Mike,

Have you, the AA or the Audi dealership confirmed the battery tests as being efficient for its purpose? 
Kind regards,

Gareth. 

[MikeSwidz]

Yes. The initial AA Roadside assistance tested the battery and alternator and all was OK. The vehicle was transported to my local Audi Garage and diagnostics were ran. It was determined that a software update was required for the generator system. Unfortunately the effectiveness of this fix will not be known until I have driven the vehicle repeatedly and covered a few hundred miles.

I now have the car back and will be somewhat nervously monitoring for any warning "pings".  

[Steve Q]

Keep us posted on how you get on 

[MikeSwidz]

Some two months on now and around 2000 miles driven - all good. Somewhat nervous initially and intentionally avoided motorways in case of fault returning, but much more confident now. Looks like the software update did the trick.

Perhaps AUDI should consider routine software updates at the time of vehicle servicing as part of the servicing schedule? It is possible that my breakdown could have been avoided had software been checked and updated. 

[Steve Q]

5 hours ago, MikeSwidz said:

Some two months on now and around 2000 miles driven - all good. Somewhat nervous initially and intentionally avoided motorways in case of fault returning, but much more confident now. Looks like the software update did the trick.

Perhaps AUDI should consider routine software updates at the time of vehicle servicing as part of the servicing schedule? It is possible that my breakdown could have been avoided had software been checked and updated. 

That's good to hear 🙂 let's hope you continue to have trouble free motoring 

[MikeSwidz]

See my more recent posting titled RED Drive System Fault/Fail.

Looks like this particular issue is related and absolutely nothing to do with an electrical fault NOR a fault with the stop/start generator.

AUDI have recently (March 2024) issued a technical bulletin to Audi Garages covering this fault.

++++

OK - mystery solved !!!

Initial diagnostics pointed to a faulty stop/start generator (AKA Alternator). A replacement was ordered and required shipping from Germany as none in the UK.

The part was delivered and then an instruction received by my Audi garage NOT TO FIT THE PART and run another check - per Audi instructions. This new check indeed revealed the root cause of the problem that I have been experiencing. The problem was due to a defective Auxiliary Belt Tensioner.

Required parts were fitted and included a replacement belt - this was more a precaution than requirement as the defective belt tensioner may have contributed to premature excessive wear.

I insisted that the car was taken for an extensive test drive before taking it back. All was well - and still is.

I now have the car back (after 2-3 weeks off the road while awaiting parts). Will monitor the situation, but reasonably confident that this time Audi have got it right.

[GeorgeB]

On 12/19/2023 at 5:46 PM, Steve Q said:

That's good to hear 🙂 let's hope you continue to have trouble free motoring 

Hello everyone. I have an Audi A8 50 TDI 2018 and I had the same issue sometime in 2022. I had RAC first checking the car and comeback with basically nothing, but just an advice to take the car to audi for an wire diagnostic which is around £150. Obviously I went and did it. Unfortunately come back with nothing from it, but they did an software update which erased my remap for what they called ''An system fault for which a recall for all Audi's A8 is going around''. I had all same issue like everyone else. I had to restart the car few times and eventually get home. After it sat for few hours the issue didn't occur again. I then had the software update. It's now been over 2 years since the issue and it drives absolutely fine with no electrical errors. I believe that everything was related to some issue with the electrical or something which was regulated by ECU in terms of level of energy using. Sorry just assumption on this as I'm no expert, but after properly interogate audi mechanics it's sounds like in was really just a software issue and nothing else. Weird symptoms thought.  

[Ramandeep]

On 10/18/2023 at 12:00 PM, MikeSwidz said:

I too have a 2019 A8 TDI and have experienced exactly that same fault - yesterday. Initially the YELLOW "Electrical Fault" came up, then within a few minutes a cascade of other warnings about other driver related facilities becoming unavailable and eventually the RED warning light instructing me to pull over and stop. I duly did and the vehicle totally shut-off. Even the central locking had packed in and I was not able to get out of the car. I tried to restart the engine and just had a rapid clicking response. The entire system was dead. Like you after waiting a few minutes the car display kicked in and I was able to restart the engine - however I did not attempt to drive off as I was about to hit the M25 and I did not want to breakdown there !!! The AA eventually recovered the vehicle and delivered it to my local Audi Garage. They are puzzled as the diagnostics did not flag anything up. There next course of action is to do a system software update - await an update.

I did not expect something like this to occur on an Audi A8. A bit scary as I frequently take the car for European holiday tours. Last thing I want is something like this to happen whilst abroad.

Watch this space for any updates.

Hi I have the exact same problem on my 2018 a8. How much would the software update cost if I didn’t have warranty and did it fix the issue in the long term?

[MikeSwidz]

In my case it proved not to be a software issue but an engine component issue - specifically the auxiliary belt tensioner. Check this out before investing in a software update which you may not need.