That part is definitely only on TT models. It is needed because the TT's run low impedance injectors and it will fry the injectors if ran without it.
The code may be referring you to the PTU (power transistor unit) which is basically the ignitor for the coilpacks . I honestly can't see that causing transmission limp mode though.
It just hit me that I think I know your issue. Is Code 41 being pulled from the TCU? If so your issue is 41 Open-Circuited shift control solenoid valve A, that I could see causing limp mode.