Codes: PO305 PO411 PO430

[Jon Klein]

I have a 96 SHO and I got codes... PO305 PO411 and PO430. misfire on cyl #5, Secondary injection air flow incorrect, and bank 2 catalyst efficiancy below normal. any ideas? cleared codes and only PO430 came back. any ideas? miss at idle comes and goes... better when cold more noticable when hot.

 

[rubydist]

The pcm looks at the o2 sensors before and after the cats, and expects to see certain behavior to confirm that the cats are working properly. When it doesn't see that, it flags the cat as being 'below normal' in performance. It could be that the cat is going bad, or it could be that one of the o2 sensors is going bad.

The most likely cause of the misfire code is a bad coil - I would replace that since its easy to get to.

If the secondary injection airflow code shows up again, I would clean the passages in the secondary injection airflow path because they are likely mostly filled with crud so there is not enough air moving.