Audi A6 1.9tdi EDC15 Lost Key Learning

This is a real case for Audi a6 1.9tdi edc15 lost key. Post it here for sharing.

Tools used:
MPPS
VAGCOM
vag commander
kess v2
fgtech

Background:
Read was ok and everything seemed fine, then remapped the original file and wrote it back, write was 100% correct but car wouldn’t start. Tool was MPPS and the file size was 0.5mb and totally fine. How this could effect immobilizer to forget car keys? I have vagcom but don’t know how to learn the keys again.
I remember now an EDC15 2.5 TDI A6 , this car has immo sector in flash.
Solution:
Got it working again. I’ve done lots of edc15 before and never seen something like this. It didn’t start when i wrote tuned file, and it was done on original file and everything seemed right and checksum ok. Ecu didn’t respond but when i kept trying i managed to write original back and it started again. Then i did it again, write tuned file and same thing, not starting and after few times it wasn’t working even with original file. Then i found original file from here with same hw/sw and wrote it and it started again. WEIRD. Tried Mpps, kess v2 and fgtech. Every tool wrote it 100% with no error messages. I found out that KESS V2 was best tool to recover it.

Flashed by OBD, this ecu don’t even have boot mode? i would do it on bench but couldn’t find way to do it, and now i need to get BDM frame if this happens again. Heard another same kind of story like mine. Audi a6 2.5tdi and immo freaked out, and they got it working with vag commander/ vagcom.

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