The diagnostic trouble code only points to where the issue is
You have to test. Low efficiency of the cat could mean the O2 sensors are not working correctly
Or wiring is suspect. Sometimes, using "Cataclean" will help??
But, if you've got the money to change it???

 

Can you help us out a little here?
Have there been any other problems, like misfire, at any time , engine running rough?
This is important because that history may point to why the code is now coming up Any unusual performance problems ?

 

 

 

I never recommend changing parts without testing
Usually this require a higher level scanner

Anyway, let us know how it goes