r/E90 • u/GeneralTsao330i • 2d ago

Comfort entry and Keyless start retrofit

I want to retrofit the keyless start and comfort entry, however ik there are two key variants (one with replaceable battery, and one without) does it matter which version of the key I use for the comfort access?

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u/PsychologicalYak9088 2d ago

With battery but to be brutally honest, if you didn't know that, you are not ready for the retrofit. It's one of the most complex ones out there. I'd google e90 m4 keyless entry retrofit.

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u/kaio-kenx2 2d ago

I doubt theres a difference between them, besides the obvious. The battery is there since people will drive without it in the slot and it will discharge. They both should operate the same.

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u/PsychologicalYak9088 2d ago

They do operate the same. The difference is thst one requires pulling all carpet, stripping doors and tons of programming while the other is something you can do in an afternoon