OBD code P0430

I'm getting OBD2 code P0430 (Catalyst Efficiency below threshhold. bank 2.)
I am thinking that this has to do with O2 sensor. Do you think I am correct on this?

I am also wondering where this 02 sensor is located. Acccording OBD2 manual, this is a engine bank 2 O2 sensor. But there are two O2 sensors on a cat on that bank; one in the front of the cat and one in the behind. Which O2 sensor do you think I should change?

it sounds like you have a bad catalyst. if it was the 02 sensor it will tell you bank 1 or 2 and upstream or downstream. so id look at the catalytic converter

According to the factory service manual, the following are the potential causes of a P0430

Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination ù Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
-Rod