On a 99-00 Si, I know the 2ndary O2 sensor is connected to the dash harness by going through a hole behind the cupholer carpet. Are EX models the same.... or do they connect to the engine harness? Do 96+ EX models even have an O2 sensor in the cat?

 

one in the exhaust manifold, and one behind the cat

si and ex harness for o2 should be pretty similiar but i'm not sure. i'm @ school with my Helms 25 miles away

 

Cool. I'm missing the o2-to-dash harnes wires for my hatch. I have a test pipe and a high flow cat, each with an O2 sensor. For track days I want an easy unbolt and plug setup.

 

the 99 and the 96 harnesses are completely different, but, the 99 si and the ex both have the secondary catalyst O2 under the car and have the wires coming up through the carpet. the dx's are different. 96-00 are the same on the dx's with the exception of the differences in the harness. meaning they are part of the engine harness ONLY.

 

Thanks. That's what I figured. It has been a while since I worked on an EX. 10 mins at a junkyard and I got the part with the first car I tried.