05-22-2007, 01:36 PM
i have been replacing all gaskets in engine bay, i had a really bad leak causing coolant and oil to mix, so i tore apart eh engine and have been replacing all gaskets and also replace both cylinder heads(this was the problem). once i put eveything back together it started up great and drives alot better. went to get emissions done and they said i had to drive it around for awhile before they could pass me since i disconnected the battery. so while driving it around my check engine light came on, went back to my dads shop and got a po420 code, which talk about the catalytic conv. i know the check engine light was not on so i am leaning towards other related issues that would cause this code. the only thing i can really figure is the ehaust wasnt attached to the manifold to ensure no leaks, i didnt tighten them down at the same time, so i think it might be offset. before i start tearing things apart again i was wanting to see if anyone else could shed some light on this for me.again, the check engine light was not on when i began to work on the car, and the only thing i did was changed all gaskets in engine.