I've been reading up on everything on here for a few weeks now, soaking up all the knowledge, getting to know the different programs and all that.

I have a 2004 Tip A6 (4z7 907 551 S), I'm curious if it is possible for me to flash code from a different ecu-box (NOT 4z7). I have VAG-COM so I can adapt/disable the immo. My understanding is that I can do this as long as the code I have is also for an auto trans, but I wanted to double check before I tried anything.

My goal here is to be able to use code which is supported by the various checksum correction programs (ECUFix in this case), because I cannot find anything that will fix all checksums (WinOLS has done the best, but leaves 1 uncorrected).

Thanks

In my experience all ME 7.1 2.7T ECUs are interchangeable.

I believe the later 2.7T ECUs were ME7.5 though. But I am not 100% sure.

Unfortunately you cannot use ME 7.1 code on Me 7.1.1 ECU not because the ECU hardware won't like it (it will run it), but because some engine hardware changed for ME 7.1.1 implementation (hence new engine designation code BEL) and it won't work properly.

You will be fine with any other ME 7.1.1 binary from 03+ A6/allroad though so if any of them is more understood than yours and have the checksums correction working ok, just use that.