You need to replace the converter 99% of the time the cat is bad. The code po430 does not say anything about o2 sensor. The correct code definition is catalyst efficiency below threshold bank 2. How many miles are on the truck. The converters are covered under the federal emissions warranty 8 years or 80,000 miles. It is mandated by the federal government the dealer can not refuse unless you have modified the exhaust or the engine.
ASE Master Tech, L1 Advance Engine Performance certified
I will not answer repair questions by PM, if you would like my input you can PM me and ask me to reply to your public thread.