Spare DME doesn't work - needs to be mapped to the immobilizer?

i bought a used dme for my bmw 1997 740il when i plug it in the engine turns over but wont start i got it for a spare the original one is ok they both have the same numbers on them dose it have to be coded or should it just go in and start i havent paid for it yet i dont know if i am doing something wrong please help thank you al

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW DME Motronic ECU Swap / Repair

[Wayne 962]

I'm pretty sure that with the 1997 7-Series, you need to have the immobilizer coded to match the DME. So, a simply plug-and-play solution is not going to happen, unless you have all of the codes for your car and have it programmed by someone with the proper software tools.

- Wayne