What is P0430 code and how do you fix it on Chevy Silverado 4.8?

Trouble code P0430 means: Catalyst System Low Efficiency (Bank 2)

I have a 5.7L V8 in my Silverado, but the code meaning is the same. There are

oxygen sensors before and after the catalytic converter. By measuring the oxygen in

the exhaust gasses before and after the cat, the computer assessed whether or not

the cat is doing its job.

In this case, it's telling you that it's not. BUT it may not be a bad catalytic converter. It could

also be caused by either or both of those two oxygen sensors going bad, or by exhaust

leaks. Those things will also cause O2 readings to the computer that are bogus and make it

think the cat isn't working right.

There are two catalytic converters. I think bank 2 is the one on the right (as you sit in the car looking forward).

I have the same problem on my 2000 Chevy silverado 1500. I changed the 2 sensor on the right pipe but problem is still the same.