So, everyone knows on the 2001 tibby theres a cat on the stock exhaust manifold, If I put on my header than that cats gone, but I still have a cat on my exhaust. My header does have a place for the fist o2 sensor will my car throw a cel if I install my header? Thanks for the quick replies guys, I know I ask alot on here lol.Also I know there's been other posts about this, but my 2nd o2 sensor is actually in front of my 2nd cat and I have no cel. So I'm a little confused about this.

 

https://www.hyundaiaftermarket.org/f..._1#entry664189



if the CEL isnt on now...it will be soon

 

If you mess with the primary cat and/or first O2 sensor, you'll likely get a CEL. Removing the primary cat will throw a CEL, just put the cat back on a week before if you have to go in for emissions testing.

 

I never got a check engine light with both of my 02 sensors before the cat, though every now and then (like once a month) I would get a CEL for being rich at idle, I assume its because of this reason. Hopefully this weekend I'll have the second O2 after the cat and the problem will be fixed.

 

both O2 sensors before the cat?

 

both o2 sensors before the 2nd cat, its been like that since the guy before us had the exhaust put on.

 

I was talking to hemmylane. Both O2 sensors should always be before the 2nd cat.

 

. . . with a cat between them to avoid throwing a CEL. Right.

 

I only have one cat in my exhaust, its not the stock exhaust. So i was saying that i have two O2's before my one and only cat