I have searched and keep coming up with different answers. Rear o2's, front o2's, precats, main cats. I'm leaning more towards o2 on passenger side but my question is, which one is that code for? The rear o2 makes since if it has to do with cats but I also don't want to replace a bunch of stuff that I don't need to. I know if the o2 doesn't fix it that I need to look into my cats but would it be precat or main?