Here comes the clue on Audi A3 2003 to 2005 cannot learn key in all keys lost situation.
Audi A3 2006 is in this one is in AKL situation and ECU is not original and in immo off.
I can’t learn key for remove SAFE with xhorse vvdi2.
Memory in dashboard is 93LC86
Audi 03 to 06 is with Fujitsu dash (chip 93C86). Micronas has 24c32 chip on all audi 8p dash.
You won’t learn a key to it with the immo off. Immo needs turning back on, ECU then needs coding to the cluster, then you can learn key.
This dash is obd job only from memory, you will need to turn immo on, and adapt clock to ecu with pin codes. Then adapt new key after making dealer key with CS.
Work out from vin details which module belongs to vehicle. Vvdi2 should do the job in diag suite. You can immo on by obd via dump tool.
Original AVDI or FVDI old with full software is better for none micronas dash. Avdi would of done that obd & added key directly to immo, don’t matter about ecu.