I have a 00 civic d16y7 engine and as we all know the stock manifold are shitty asfuck so I got some after market headers. But I was wondering and maybe is a db question but if I relocate the cat and secondary o2 sensor would a CEL? I just want to be sure is gonna work b4 I start changin ****

 

A simple question yes, not a DB question. The "DB" part comes in when you didn't try looking for this information on google first. And when you used texting shorthand. That will tick alot of people off.

Stepping off the soapbox , putting the cat further downstream will slightly reduce its efficacy, but if you wrap the header then you shouldn't see any changes. And as long as the 02 sensor extension is SOLDERED and shrink-tube sealed.

 

So by doing that i should not Get a check engine light?
Thanks for the help man 👌

 

to avoid a CEL replicate the factory layout: engine followed by the primary O2 sensor followed by the cat. followed by the secondary O2 sensor.

like Tachi mentioned, the further from the engine the less efficiently the cat will work (especially at start up) but that won't pop the light on if the cat is in fact working.

the ECU looks at the primary O2 to figure out fuel trim (rich or lean) in open-loop (pretty much anytime you're not at wide open throttle [WOT]). the input from the secondary is compared to the primary so that the ECU can judge the effectiveness of the catalytic converter. it's purpose is purely for emissions.