Do i tap the wire into the O2 sensors? and which one is it.. there are two white, one gray, and one black.
thanks

 

black is ground - so that's not it. I don't know about the white wires, but i feel the gray is the one - but i'm not 100% sure.

also, is this a wideband O2 sensor? because the stock O2 sensors are not "accurate" enough to give you the correct stoichiometry reading - therefore rendering the A/F gauge just a pretty light-show.

 

on civics, there are 2 green, one white and one black. I connected mine to the white. That makes it the odd man out. Gray should be right.