I asked this in another thread and it wasn't answered in enough detail for me to get the idea of where, but where does the o2 bung go on a 2000 Civic EX? Would be AWESOME if someone happened to have a picture of where it goes so I can tell the muffler shop where to weld it. I was just told that one goes before and one goes after....but where after the cat? Does it matter? A picture is worth a thousand words as they say, that way I know exactly where it goes. Also, how can I get to it. I saw that it went up through a hole in the bottom of the car but couldn't see it through the engine bay. Help would be much appreciated.

 

i wish i could help i know on my 94 if i pop the hood and right near the back of the engine bay near the winshield if i look straight down... there is an o2 sensor... and i think the second one goes like maybe a half foot from the cat but im not 100% positive

 

See if this PHOTO is detailed enough for you.... FYI, #28 and #41 are the O2 sensors and #4 is the cat. You can see #41 goes in at the end of the stock A-pipe and #28 goes into the back side of the cat.

Yes it DOES matter. The OBDII ECU requires a O2 sensor before and after the cat to measure catylist efficiency. You'll get the dreaded P0420 if you don't put them in the right place.

 

Looks to me, as you said, it goes in the piping right past the cat. Would that be correct?

 

dude I told you in your last thread......primary goes before the cat....secondary goes after....how hard is that to understand? :thinking:

put the primary just ahead of the cat and secondary just after. like within a few inches. no big deal.....the primary will get the readings it needs anywhere before teh cat....and all the secondary o2 sensor does is tell you that your cat is ok.

 

if you would have said it like that the first time i wouldn't of had to ask again....just saying it goes after the cat tells me i could put it down by the muffler and it would be ok, know what I'm saying? thanks though, my question is answered