So as the title says i am experiencing this code first hand. Little back story, its my wifes car. Runs completely normal, no bad idle, starts and runs fine. Gas mileage is about normal. may be a couple miles off a bit. i don't drive it so i can only go by her word.

Car has 121,000 miles.
Changed spark plugs and air filter today as well as oil.
Took it to my mechanic, trustworthy guy I have been using for years. He thinks its the catalytic converter.

Im not asking what the codes mean as i have researched it and i know what it means.

I am asking those who have had this problem what exactly did you do to resolve it and what are my best options for fixing this.

It needs to be inspected and live in texas which does require emissions testing.

Thanks, any information would be helpful.

Could be O2 sensor. Catalytic still need to be inspected.