CEL P0431 code but passed smog emissions in CA - does this mean CAT is not issue

Code was P0431 but I passed my emissions but failed visual and functional due to the light. So I'm wondering if the CAT was bad, I wouldn't have passed emissions, correct? I need to get he CEL off to pass my smog, so I want to know the steps to take to check all emission related parts. Thanks!

go to a AAA approved smog shop and gety an diag and est. just because the code points a special parts does not mean repl part it could be the circuit is bad or other related system

Thanks for your input. Would I just ask the smog shop to perform an intrusive test on my cat to see if it's good? or do I have to go through the whole test again for them to get a diagnostic?