I was afraid of this. I am putting a new header and catback system in (98 civic ex). Here is my problem: My header has 2 bungs for O2 sensors, but there is not one on the back side of my new cat, what do I do? Should I put the O2 senor that is supposed to go behind the cat on the 2nd header sensor spot? (wouldn't that just send a singal to the computer and try to lean it out more?) If I don’t use the O2 sensors at all will that mess things up? (I have plugs for the header) This needs to go back together today, so expedience is a necessity. Thank you

 

You need to pick up and o2 simulator... that all i know about it. Call your auto stores to see if they got em.

 

I feel like an idiot, catBACK. I can rebuild hotrods all day long, in fact my first car was a 67’ Camaro I rebuilt from a box of parts and a rolling chassis, but you get me underneath a newer car and I turn into an idget. This is the first time I have ever wrenched on an import. I will use the original cat, it just never occurred to me. I didnt even buy a new cat, hince the name catBACK I am sure I will have many more ridiculous questions in the near future!!

 

Alright, I have finished, but, I have an exhaust leak. I know where it is coming from, but am not sure how to fix it. I am having a problem getting the cat to mate to the header. I think it is a compression seal (instead of a gasket), if that makes sense, because it did not have a gasket when I took it off, and the new gasket I have has no effect on it. Do you know what I am talking about or does this make no sense? Does anyone make an adapter to connect to aftermarket headers on one end, and on the other end something to mate to the cat?
Thanks
Matt

 

use some super high temp rtv and fill it up

 

I forgot the doughnut gasket that goes on the header![&:]
Thanks!