Hi Esse10. Sounds like you have a tough one there. I had a couple of thoughts:
Try reading error codes anyway and see if there are any. Especially if you have VCDS there will probably be codes there that could provide a clue.
Second, look at the live data while driving to be sure the ECU is getting all the readings it should. Look for things like RPMs, vehicle speed, engine load, ect. to have readings that are updating.
There sure seem to be a lot of problems cropping up when batteries on these cars run low!
Try reading error codes anyway and see if there are any. Especially if you have VCDS there will probably be codes there that could provide a clue.
Second, look at the live data while driving to be sure the ECU is getting all the readings it should. Look for things like RPMs, vehicle speed, engine load, ect. to have readings that are updating.
There sure seem to be a lot of problems cropping up when batteries on these cars run low!