MikeSwidz

Has anyone viewed my original post on a very similar issue posted some 3 years ago? If you have not then I suggest that you do. I have an Audi A8 S-Line TDI bought from new - 2019 registration and possibly one of the first from the new design flight at the time. I have had the car serviced annually by Audi and at no stage has it had a recall notice. I suffered a severe "Electric Failure" yellow alert, followed by a cascade of other faults and an eventual "RED" (you're dead) failure back in October 2023. What was scary was that the car went totally dead after I stopped and I could not get out of the car as the auto door locks had also frozen. I was locked in - this is potentially a SAFETY ISSUE ??? After a minute or so after shutting everything down I went to restart the car - and bizarrly everything was OK. Doors openned, the engine started and no warning alerts. I was on my home from Suffolk and about to go onto the M25. Did I want to take the risk and continue believing that everything was OK? No Way !!! The car was recovered by the AA and deposited to my local Audi dealer. After dignostics - which took several days to carry out as the car had not been booked in - Audi located the fault in the fault log but could not reproduce it. "Things" were reset and the car returned to me. All OK for a few months and then the same started happening again, but this time no "Electric Failure" but immediate fatal "RED WARNING" and engine stopped. I figured out that by pressing the Stop/Start button I could clear the fault and drive on. Went back to Audi - but this time for a pre-booked investigative appointment. Audi determined that the fault was with the Stop/Start Generator (aka Alternator). As the car was under extended warranty this would be replaced by Audi - but the part was not in stock in the UK and I would have to wait around 10 days. Was I offered a courtesy car - nope. Had the car been recovered to Audi (by the AA) then yes, but I had driven. Huge minus Audi Customer Services!!! I had assumed that since this was a repeat fault/failure and given that I was provided with a courtesy car first time around that another temporary vehicle would have been offered. Nope - I had driven the car to the dealership and it had "not broken down". What a pain. After about a week I got an update from Audi that their technical team back in Germany had also investigated the car's diagnostics and suggested that the problem may not in fact be with the Stop/Start Generator but with the Auxiliary Belt Tensioner. This was duly examined and a new belt tensioner fitted (as well as new belts). Since then the car has performed brilliantly without fault. So - if you have not already done so then can I suggest that your Audi mechanics look at the Stop/Start Generator auxiliary belt tensioner system. Much cheaper to replace than the Stop/Start Generator. If having an extended warrant worthwhile? Personally, yes. Hope this helps.

I posted on a related topic with my Audi A8 some 4 years ago. Audi initially attributed my RED LIGHT fault issues to the Stop/Start Generator (aka Alternator) and were going to change this out. After further investigation it turned out that the fault was with the auxiliary belt tensioner. The auxiliary belt tensioner was fixed/replaced and a new belt fitted. This well and truly fixed the fault. Suggest you investigate the auxiliary belt tensioner - as this may be the root cause. A lot cheaper to fix than replacing the alternator (which may not actually need replacement. Hope this helps.

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.

My local Audi is in Worthing (Roundstone). Tell your Audi Service Dept that Audi have issued a bulletin (March 2024) regarding this fault and that it has nothing to do with the stop/start generator. If they find nothing then ask them to get in touch with Audi Worthing for details. The cost of the repair (parts/labour/VAT) was around £200. Hope this is the "fix" for your fault.

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.

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.

Thanks Jason. If the car is indeed stalling does this point to a transmission or clutch issue? Hydraulics? Hopefully more will be revealed next week.

Regarding your Point 3 - no, not that I've noticed. A bit difficult keeping an eye intentionally on the Rev Counter whilst driving ;o} I too have wondered if the car is stalling at low speed. Bit unusual for a diesel automatic - but you never know? Would the RED Drive System Fault/Fail light come on if the engine stalls?

Regarding the Software update - will do. Regarding the points you raise in item 2: 2. I've read (web posts) that the engine management system may have a default engine rev limit of 2500 RPM for the V6 TDI when stationary to prevent over revving? I Will never the less report this to Audi when I check the car in for the diagnostics check. 2a. Probably. I guess this is an original factory setting. 2b. Yes - steady at just under 1000 RPM 2c. No - steady on tick over.

Hi Jason, a follow-up to your Waste Gate Actuator fault suggestion: 1. So far the RED Drive System fail/fault and engine shut-off has only occurred at low town driving speed. 2. I did however follow up on your Waste Gate Actuator suggestion. I did a self test by trying to rev the engine hard in neutral. Interestingly the engine refused to rev past 2500 RPM. Not sure if this is by Audi design or whether indeed there is a fault with the Waste Gate Actuator or Turbo System. 3. No warning signs come up when I try to rev the engine hard - just the limitation of RPM to around 2500 RPM. Car goes into Audi garage for diagnostics check next week.

Yes, it's an Audi A8 V6 50 TDI - first registered July 2019. As mentioned, there is nothing showing up on the cat fault log history that I can access as driver. Would the OBD codes show up during the car diagnostics check?

My AUDI A8 (Diesel) has experienced several random but immediate engine shut downs at town driving speed resulting from sudden and unexpected RED "Drive System Fault/Fail" warnings flashing up. This has now occurred 4 times in as many weeks. The car is booked in for a diagnostics check with Audi. Fortunately all the faults and engine stops have occurred at relatively low speed. However, as the engine cuts out immediately there is no chance to pull over safely and I have caused traffic to back up as a result of the occasional mid-road "breakdown". The engine restarts almost immediately after stopping and the RED fault light clears. No other warning lights come up prior to the RED warning. The fault has so far not occurred at motorway driving speed - and I hope it does not given that the engine shuts off immediately. The car is regularly serviced by AUDI and no modifications have been made. I have been using the same fuel and fuel stations that I have done since buying the car from new in 2019. What is odd is that the warnings appear to be clearing and not showing up on the car warning and information log NOR on the myAUDI app. Any ideas/suggestions?

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.

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".

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.