I know this post is a bit old so not sure if you already fixed the CEL issue, but I had the same P0430 code a few months ago. It turned out to be the driver side pre and post cat o2 sensor that was causing the problem. My X still had factory ones and once I replaced them, the problem was fixed. Catalytic converters hardly go bad and they are expensive to replace.

The system is giving the error because the old o2 sensor was probably fouled up and giving the wrong voltages. The computer thinks the cat is not doing its job and throws the P0430 error. The knock sensor error also went away after I replaced the o2 sensors.

Car runs good now and fuel burns clean. Hope that helps.