Will the ecm affect my smog test?

I think my ecm is bad in my 96 Honda civic ex 5speed. Can I change the ecm? Do I need to find the exact matching ecm or can I use a different year ecm? Will it affect my smog test. I don't wanna buy a brand new one so I'm thinking of buying a used one from people parting cars or a parts shop. It's hard to find exact match that's why I want to know if it matters also I gotta smog test pretty soon.

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