Okay so I just...looked up o2 sensor in search and read the topics that I thought pertained to me. So I understand that you have to replace your o2 sensor and the wiring...I got that. There is one o2 sensor before the cat and one after...but what is the "primary o2 sensor"...so are there three o2 sensors total? The "primary sensor" is located on your headers...huh??

Sorry for the dumb question...couldn't find anything much

 

primary is the 1st one, secondary is 2nd. on all 94+ integras except the 94-99 gsr the primary is in the header, secondary in the cat. on the 94-99 gsr they're both in the cat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vladd &raquo;</TD></TR><TR><TD CLASS="quote">primary is the 1st one, secondary is 2nd. on all 94+ integras except the 94-99 gsr the primary is in the header, secondary in the cat. on the 94-99 gsr they're both in the cat.</TD></TR></TABLE>

So mine would be on my header...and my second one would be on my cat...any one have pics of these so I know where to look? Or can anyone else explain please =]
Much thanks

 

they're pretty obvious. they're the only sensors you'll see in the header and cat. just get underneath the car a little behind the front wheels. 4 wires come out of each one.

 

https://www.acuraoemparts.com/...2.gif
see if this helps to give you and idea.
25 is the primary 26 the secondary,