So unburned fuel will break down the catalyst inside the converter that is responsible converting harmful emissions to non harmful. This causes it to be "hallow" and not efficient. When oil, coolant, and water go through the converter it actually clogs it up and causes it to be less efficient and set the light. So if you have a code for catalytic converter inefficiency then more than likely it is clogged or restricted.
If you are replacing that, I would just go ahead and put new o2 sensors in it as well. You are there and it is not much more to just renew it all at the same time because what ever went through the converter also past by the sensors and the tips can get clogged as well.
Let me know if you have more questions. Thanks
Saturday, August 3rd, 2019 AT 9:26 AM