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722.9 Gearboxes can use different control unit (TCU) versions, which can be interchanged. Anyway these units must use different software versions. You can find proper software here: 7G-tronic Software Finder
After each replacement of 722.9 transmission control unit to higher hardware level, also new SCN coding need to be determined and changed. This tool can help you to find the best suitable replacement for your old SCN string. It let you also know the meaning of coding string values. The choice of replacements is based on similarity of settings. Each field have many possible values which are available for particular cars (based on car equippment). Fields market as green are obligatory for matching the same car. Other fields can vary, depending of function meaning and availability. You can change settings and behaviour of your gearbox by testing different codings.
VGS Versions with part numbers A 033 545 66 32 and A 033 545 67 32 (1 Generation) use coding strings with starting letter "V" VGS Generation II with part number A 033 545 73 32 use coding strings starting with letter "X" (in some cases coding "Y" can be also accepted) VGS Generation III with part number A 003 466 03 10 can use strings "Y" or "Z" depending of software version.
NOTE: There are no "V,X,Y" replacements for "Z" codings! Software versions using "Z" will not accept older string construction. To be able to change coding by units using "Z" strings, you will generally need to unlock your TCU.