Had a problem on my 2013 A3 8V 2.0 TDI Some mornings(and after driving sometimes) when on start up, after say 20 seconds the glow plug light would start to flash and put the car in to limp mode, which gave a code via the Carista app of P2563(a couple of times while driving as well). Which is to do with the turbo. Also sometimes i would see Start/stop function unavailable on the display with the glow plug light flashing. It was becoming a real pain. I even had to unplug my tuning box as well and drive round in "stock", which seemed to make it worse( i expect that was to do with over boost, which is what the tuning box does). Well after loads of research, i thought i would give a turbo cleaner product ago to see if the turbo vanes and/or the turbo actuator was sticking/blocked ?. Popped in to my local Halfords and got a bottle of Wynns Turbo Cleaner and pored it in on top of the V-Power diesel i all ready had in there(three quarters of a tank). WOW, driving home from work it was noticeable straight away!. More power, response and more importantly the car has gave NO glow plug light flashing after 2 and a half weeks of driving. Its like driving a new car! I have also reconnected my tuning box with everything AOK after driving the last 5 days with it on!. In my case it must of been a dirty turbo that was giving me all the problems. So if you ever get what i went through, before taking your car somewhere just try out a turbo cleaner! Oh and i must add i am also trying out a different cleaner from Forte(2 bottles to a tank) just to make for a even more complete clean. Again the car has been awesome. I will use the Wynns stuff every 4-5 top ups, to keep thing clean and free from carbon build up!