Okay so after quite a bit of troubleshooting, it turns out that my exhaust manifold is cracked (whether or not this caused the o2 sensor to go bad, i don't know).

So my first question is: can/should it be welded? If not, does anyone know where i can get a california acceptable manifold? i haven't been able to find an aftermarket one, only from honda...

any help is appreciated :)

rachael

Take the car to a good muffler shop. Of course it depends on the location of the crack, but sometime they can weld the cast iron manifold without a problem. The other option is to go to s junkyard and pick one up. Like you say aftermarket manufacturers make headers, not exhaust manifolds. Anyways, good luck.

I had the exact same problem as you. Don't know about welding it but I had mine replaced (the Cat). around $800 - my o2 sensors were fine. I actually drove with it like that for a few months and didn't have any problems - I only had it fixed because it was time for my emissions test. Good luck getting yours fixed.

i had this exact problem as well..
I actually drove my car for about a year with the manifold cracked.. hah!
stock manifolds are expensive... so I did this:
bought a header with an o2 bung..
and installed a straight "racing" cat for the secondary o2.
works like a charm. =)

As for welding it... not such a good idea.. My best friend is a welder.. he welded my manifold.. and it only lasted for about 2 weeks...

Oh.. by the way.. the crack gets worse if you do nothing about it..
I was probably down to about 85 horsepower.. haha.. oh ya.. it was NICE..
Annd.. yes.. the manifold being cracked will effect your o2.. I replaced it twice in that year..
damn Im lazy..

You can have the manifold welded with a powder tourch welder with 100 percent success I have been welding cast iron exhaust manifolds for the last 15 years every thing from cars to boat and tractor manifolds with no problems.