How do I know if my catalytic converter is defected?

The only way you know your catalytic converter is not functioning properly is by measuring the exhaust gas oxygen before and after the catalytic converter, via the pre and post converter heated oxygens sensors. I would say unless you had some kind of sustained fuel system trauma, such as raw fuel going into a catalytic converter frequently and sustained that your catalytic converter is probably working as intended. Hands on testing is needed. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops