I've had my check engine light scanned twice with the same problem of the catalytic converters missing. I had them clear it and it came back. I'm not too sure how to check and if they are missing how can I go about preventing the light from being on? I've ran gumout through my fuel tank in the last week and it hasn't done anything for me yet. Not sure what the problem is, or how to solve it. Any advice PLEASE HELP!!!