Idle

For awhile i though one of my 02 sensors was messed up because my check engine light would keep coming on and i had to extend the secondary 02 sensor wire my self. I always thought I wired it worng so when the check engine light would come on i thought it was because of my poor wiring. Today i went to honda and they did a quick system diagnostic and to my suprise it wasn't the 02 sensor but it was the IDLE CONTROL VALVE, I have never heard of it.. It's located right around the throttle body and intake manifold. Can anyone shine some light on this for me before i go out and blow 300 to fix it.