Cold air intake, Vacuum Tube?

Installed a cold air intake on my 02 2.7. There's a vacuum hose that went into the airbox across the radiator shroud into a little piece on the driver fender. I just unhooked it from airbox and left hose open and dangling by windshield washer jug. Now I'm getting a check engine light. What does it do and how can I fix?

 

Go figure.*



*I recognize this was a pointless, narcissistic post but the internet provides me with a few certain inalienable rights.

 

I'll get ya a pic when I get off work in the AM. But it's pretty hard to miss. It finds from driver fender across the top of the radiator shroud into the stock air box. It's the only tube that plumbs into the airbox. Can't see it doing nothing major. But it was major enough to throw a code just by unhooking it. My thing is what do all the guys do with it that have intakes? Just T it off into another vacuum line?