Fault code P0420 Common Fix- replace oxygen sensor

What is your question?

Fault code P0420 is common in Audi's. And it refers to an inefficient catalytic converter. However, I have found that the fix for this fault code is seldom the catalyst itself but rather replacing the oxygen sensor. I was hoping that someone could expand a bit on what they have read or seen in their experiences with Audi's? Thank you all and have a great day.