Hey guys,

I recently flashed a MK4 GTI ECU (HJ box) with a file without doing the checksums and haven't been able to restore it so I bought a new ME7.5 ECU, my surprise was that went I opened it the chip in it was a 400BB chip, now, if I defeat the immo on this 400BB ECU, can I flash it with the HJ box .bin file and run the car?

Thank you,
GWerks

What about the reverse? flash 400bb file onto 800bb ecu?  i could solder in a 400bb chip if necessary

reason i ask is because i have a customer who has a 2000 audi TT with narrow band ecu the has a checksum error . audi dealer wanted to replace ecu, i told him i could reflash it. so i did and while i was in there i changed a few maps for some more power as he requested with winols.  it was fine for a few days now he says the CEL is back on but i haven scanned it yet to see the fault code is( hopefully its not checksum error).   but just in case it is, i wanted to replace the ecu , but i dont have any 400bb narrow band ecus, however i have a stack of 800bb wide band  ecus i could convert to narrow band .bin file if you are right ddillenger.

post your tt file and i will correct checksums

this is not my problem, i can correct checksum with winols.  turns out it was an evap error,  so my reflash of ecm fixed checksum error so far.

i work for VW so i run into checksum error all the time on newer cars, and solution is to replace ecm, techs dont have access to reflash ecus unless it is a recall/update with a 4 digit update code for online server reflash.  only vw engineers have this capability.