Dx header/420 code

[ManTyme]

i think the catalytic converter in those civics are part of the exhaust manifold. since you put the aftermarket header in you eliminated the cat. just put your original exhaust manifold back in and clear the codes and drive the car a few days before taking it to emissions.

x2 dx cats are in the header mani

[Chillmatic]

i dont have the stock one thats y im trying u get this to work i no it works u cant tell me peolpe dont put headers on this cars all the time

[H22SteakSauce]

Yea I do. Then I get an ex cat and weld it in and it has the o2 hole

[shooktd]

so what youre going to have to do is this. http://www.aptuned.com/mr-02fix

also helps with steal wool in side of that peice

[Drag0n97]

I did after market header in my cat I just put the o2s where they went and no probs

[Chillmatic]

Moved the sensor to behind the cat and it throw the 420 code again catalyst system efficiency below threshold bank 1

[Chillmatic]

I did weld the first o2 into 2 and 3 cylinders it is only suppose to be in cylinder one ?