What catalytic converter should I be changing?

Question

I have '04 Mazda 6 that is showing a code of P-0431 Bank 2 Below Threshold. People have told me that the code refers to the back Catalytic but I am not sure?

Answer 1

P0431 Warm up catalyst below threshold (LH)

This is for the left hand warm up catalyst which is the front before the main catalytic convertor