I have change the 02 sensor and still get that code. What else could it be?

Jim, check this out.

https://www.askmehelpdesk.com/cars-trucks/when-asking-about-your-vehicle-303903.html

It is telling you the cat converters are not doing there job... they need to be replaced. What year of car,truck? May be coverd under emission warranty 6year 60k. 8y 80 k..?