Any specific codes making you say that? I too have emissions related codes that I have tired some amount of trouble shooting but eventually just assumed it to be cats (216k on original cats)

Have been getting these codes the last few months. Although, using Cataclean the chrck engine light went away and I was able to get the car to pass smog.

P0430
Catalyst System Efficiency Below Threshold
P0420
Catalyst System Efficiency Below Threshold

Cats have a life expectancy, of course, but they are very durable. Poor mixture control can cause early issues. Related codes absent of other issues can be caused by vacuum leaks, exhaust leaks, bad or failing O2 sensors, and a multitude of other things.

225,000 miles 35i gas.