my buddie got a used S2000 and the owner replaced his aem intake back to the stock one... now the check engine light came back on.

I had it reset at honda but it popped back on. I'm told the code is about some kind off "intake blower" missing...

does anybody know what this is???

 

This is a common mistake that people make when installing a CAI. Your vacuum lines are crossed or your one way check valve is backwards or one of your vacuum lines are cracked and leaking.
Go the the "Technical" part of Under the Hood and look at the top of that forum. You will see a thread "FAQs ................................ " In there, are listed all kinds of links to "How To's". One of these shows you how to trace the vacuum lines and make sure they are correct (after installing a CAI). Also, another thread in there shows you how to reset the CEL so you don't have to go to the dealer.