Hey guys and girls!New on this site so bear with me ok!Well my newly accquired 2003 mustang convertible has been lighting up the check engine light regularly even when i clear it out.Reads code that catalyst effeincy not working properely,i believe it is code 410?Replaced o2 units but still pops back up.anyone can help mewould really appreciate itoh also its bank 1 side/Who the heck knows!!!!

 

Sounds like you have a converter going bad

 

I had a similar problem I tightened my gas cap really tight so no air could get into it and that seemed to work for me

 

cat efficiency code means you needs some new cats... or rear 02 delete harnesses lol..