Hello everyone, it's been a while now since I made the repair of the car, I can tell you that from that day on it hasn't happened. The machine has never shut down, even after 2h in a row.
The problem for me was the control unit under the steering. I leave here the code of my ECU, maybe it is easier to find it:

 

8P0 953549k 

0070 SW

037 HW

 

This problem appeared to another person with the same car but slightly different symptoms and a pre restyling version, he too was able to solve it by changing it and it has not happened since that day (some months ago)

 

 

On 12/28/2024 at 9:14 PM, Sid2020 said:

Totally understand, only raised the battery issue due to a previous post, I carry out electrical and programming/coding repairs every day as part of my job and often use the phrase @ im sure” instead of saying “i know” as it often comes back to bite, I know that the BEM battery code is a VAG system but wouldn’t rule out a another vehicle manufacture adopting the system, sorry for any confusion as only won’t to provide help or direction to users 

Hi BEM codes are peculiar to any vehicle using VAG software, Bentley and Lamborghini being amongst them Ford and GM use a battery counter system which can be reset on the dash pod, Alfa Romeo use multiple model systems but they are all basically counter systems with different modes of reset, and then you have the Mito which requires Fiat Multiscan to reset it, as you pointed the BEM coding is a VAG system which is why its a source of many discussions on this site, its what their system demands to ensure longevity of the battery, yes not many batteries come with a new code but it is easy enough to make a new code from the existing code just by changing the last two digits of the old code, therefore the ECU recognises the new code and informs the BEM which relearns its charging values taking in the voltage maintenance of the new unit.

Steve.

Had a problem with my old girl a couple of years back, stopped dead, after 15 mins it would start again, then after 8 or so miles would stop again. This turned out to be a dodgy crankshaft sensor. 

On 7/1/2024 at 3:35 PM, Audi-Inny said:

W zeszły weekend wymieniłem pompę paliwa wysokiego ciśnienia (HPFP) w moim samochodzie. Dzisiejsza temperatura wyniesie 40 stopni Celsjusza. Testuję więc teorię, że to wina przegrzewania się pompy HPFP. Czytałem, że całkiem możliwe, że przyczyną jest jazda z niskim poziomem paliwa w zbiorniku. (Czytałem o tym cały tydzień). Na pewno tu wrócę i napiszę. Po powrocie z pracy. (Życzcie mi powodzenia…)

I have the same problem, did you solved it? Please tell me. Thanks for Your time. I have a idea - replace ecu. 

Edited July 23, 2025Jul 23 by Oskarek

I had a similar problem with my A3 the car just stopped and after about 10 - 15 minutes it would start again, ran for maybe 20 minutes then stopped. kept on doing this so i took it to my local garage, they diagnosed that a sensor had failed on the crankshaft, It was replaced and that solved the problem

3 hours ago, Fly Fisher said:

I had a similar problem with my A3 the car just stopped and after about 10 - 15 minutes it would start again, ran for maybe 20 minutes then stopped. kept on doing this so i took it to my local garage, they diagnosed that a sensor had failed on the crankshaft, It was replaced and that solved the problem

I had that sensor replaced – it’s not the cause. I have errors related to the air conditioning sensor – short to ground, and the ECU – no connection. I’m considering replacing the ECU.

On 12/30/2024 at 9:46 AM, Elit99 said:

Hello everyone, it's been a while now since I made the repair of the car, I can tell you that from that day on it hasn't happened. The machine has never shut down, even after 2h in a row.
The problem for me was the control unit under the steering. I leave here the code of my ECU, maybe it is easier to find it:

 

8P0 953549k 

0070 SW

037 HW

 

This problem appeared to another person with the same car but slightly different symptoms and a pre restyling version, he too was able to solve it by changing it and it has not happened since that day (some months ago)

 

 

I did what you did. And it solved my problem. I replace almost every part that I read on here, AND other forums and such. I meant to answer a question from someone on here. ( July 23rd, I think. Message, to me, had to be translated into English.) I realized after changing the wheel angle sensor, which you supplied the part number (yellow/black squarish box under steering column attached to the ignition tumbler), that it stemmed from when my key would not turn, where I twisted my key so bad.l, I was trying to resort to anything to get it to turn before replacing the ignition. So a coworker of mine, at the time, told me it happened to him in another make and model car. So he would spray wd-40 into the key slot and sure enough, it worked for me. But after about 3 days, the ignition would get stuck again, into the ‘on’ position, with the instrument cluster lights on. So I desperately did the wd40 again, and it would work. I finally replaced the ignition tumbler. But after some time, my car suddenly would stop while in motion. My other post has a full explanation of remedies I did. So, my conclusion… wd40 shorted the circuit(s) in the wheel angled sensor. And once it hit a certain temp, car would just die. Thanks so much for your info. I would’ve never thought to change that part. Because I did it all. God Bless… again, thanks! My car has made a 325 mile trip and back (round trip 650 miles) without issue. It has now gone thru 2 months of sweltering heat of 109F degrees. So relieved!

Edited August 9, 2025Aug 9 by Audi-Inny

On 7/23/2025 at 6:21 AM, Oskarek said:

I have the same problem, did you solved it? Please tell me. Thanks for Your time. I have an idea - replace ecu. 

Already tried the ecu. Wheel angled sensor. Replacing ecu/pcm did not work. So after replacing the wheel angled sensor, car is running fine. So, I put my old ecu/PCM back in. And still running…

1 hour ago, Audi-Inny said:

Already tried the ecu. Wheel angled sensor. Replacing ecu/pcm did not work. So after replacing the wheel angled sensor, car is running fine. So, I put my old ecu/PCM back in. And still running…

So the issues you had with the car not starting and stalling on hot, sunny days were caused by that sensor? Do I understand that correctly?

On 2/1/2024 at 6:46 PM, cliffcoggin said:

Aram.

Można rozważyć dwie możliwości:

Deski rozdzielcze w A3 są podatne na awarie, zazwyczaj z migającymi światłami lub po prostu przepalają się. Nie słyszałem o takiej awarii, która spowodowałaby awarię silnika. Naprawa deski rozdzielczej przez specjalistów jest znacznie tańsza niż w przypadku nowej deski rozdzielczej Audi.

Wadliwy akumulator może powodować pozornie niezwiązane z nim problemy elektroniczne, na przykład z tempomatem, radiem, klimatyzacją itp. Ponownie, nie słyszałem o takiej usterce, która spowodowałaby awarię silnika. Nawet jeśli akumulator łatwo odpala, nie oznacza to, że jest w dobrym stanie. Jeśli ma więcej niż pięć lat, warto kupić nowy. Nie zapomnij go zakodować do samochodu.

My car either won’t start or starts and then stalls on hot, sunny days. The issues reported by the ECU include: no connection with the ECU, an air conditioning sensor fault – short to ground, a cruise control issue – strange communication, and low voltage on the CAN bus. These problems occur sporadically. From your experience, could this be caused by the battery? When the car cools down (is in the shade or the days are cooler) it works normally. But if the car starts and then stalls after driving 1 km, the battery probably doesn’t have much to do with it, right?

Edited August 9, 2025Aug 9 by Oskarek