What is the yellow sensor on the thermostat housing?
If anybody can help that would be straight.....

 

I believe it is your Cooling Fan temp. sensor.

 

will i throw a code if that's not plugged in?

 

Yes it will.

 

there's that plug^ and then theres the plug on the left side of the head, they are both two prong it's confusin the hell out of me.... because when i first started to do my swap i was using a wire changes write up, that told you what with what from civic harness to prelude, and later on down the road i found out i had an itegra harness I think i'm gonna go through my wiring all over again....

 

Yeah, there is the 1 prong under the dist which is the coolant sending unit (to your gauge cluster), then the ECT (engine coolant temp) which is what you are referring to on the side of the head, then the fan switch on the thermostat housing.

 

appreciatte the help man!