check engine light came on and code was catalitic converter.

Hello, if your catalytic converter is not doing it's job to reduce exhaust gases properly, but the vehicle is otherwise running normally -- you could technically wait to replace it until you have to pass a state emissions test. You'll be doing damage to the environment by waiting, though, which is a moral concern. If engine performance is suffering as a result of catalytic converter restriction or flow issue, then it'll need to be replaced right away. Testing should be done to ensure the catalyst itself is at fault, not software nor the air / fuel sensors before and after each catalytic converter. www.repairpal.com/repair-shops