Dx header/420 code

[Chillmatic]

I have a 99 dx civic and I put. Cheap header in it I had to weld a bung in for the o2 Sence up by the head and the other one was is down under the car right before the cat but it keeps throwing the 420 code which means a bad cat and I have to go though emmions soon what do u think I should do ?! Thanks

[H22SteakSauce]

You just stated your problem. You welded a bung before that cat. Smh you need the second o2 sensor to be after the cat and u won't have an issue.

[Chillmatic]

O and it's bank 1

[Chillmatic]

It's bank one and no the headers come with both o2 in front of the cat

[H22SteakSauce]

What?

[Chillmatic]

No I looked at all the after market headers and both o2 r before the cat

[daveedd357]

420 code just smoke it. Just kidding. Do you have a cat? Also is the secondary sensor behind it?

[daveedd357]

The sensor needs to be behind the cat.

[daveedd357]

There are devices that limit the amount of exhaust that go to the secondary sensor to trick the ecu into thinking that the cat is still there.

[Chillmatic]

How come on all the headers it's not it's right before the cat so ur saying if I weld a bung in right after the cat the code will go off but what's bank one mean then ? How do I do that make the o2 wires longer?

[Chillmatic]

Bank 1 is the the sensor that goes behind the cat. ?

[Can~i~bus]

420 means burn something

[ct tibby]

simple fix. take the secondary get 2 spark plug non foulers drill one out thread it into the other one put the 02 sensor into the top. then screw the bottom into the exhuast. it limits the amount of exhuast fumes it reads making it think there is a cat on the car when there really isnt

[JayZeeGee]

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.

[H22SteakSauce]

^^ I still got it