99 civic with converter code
 

but the converter is beautiful, replaced both O2 sensors. I was going scrap the whole system for performance but $ is tight. Could it be the muffler? Also I saw where a bad ground could be the issue. Any help appreciated. Also is a header worth it? Still running stock. I'm an old school V8 hot rodder, but it looks as if this may be my new project. I need it to last about 5 more years, and if I'm driving her, she needs more oomph. Thanks.

I have the same issue with my 99 civic, cleared the code to see if the problem is recurring.. its been over an month and 3k miles and the code has yet to pop up again. I'm thinking its a fluke, or my cat is slowly clogging up. Idk about a bad ground bc I haven't really looked to chase it down. Lol

thanks
 

good luck and happy new year:)

Thanks, same to you.