On Board diagnostics code P0430

[Hucky]

Hey men

I had an engine light come on the dash yesterday, All gauge functions, such as temps, etc.. are normal, but the engine check light is on.

Today I stopped by Autozone and plugged in the OBDll into the inlet on my Rig, I got 2 codes, 2 of the same codes P0430, I then printed out a definition of the codes on paper. After unplugging the tester from the inlet on my rig, the code went away?

catalyst efficiency low-bank2
explanation

The oxygen Sensors monitor the catalytic converters ability to store oxygen.

Probable Causes-

1-Catalytic Converter defective (failure possibly due to #2, #3, #4)

2- Engine misfire or running condition

3- Large vacum leak

4-Engine oil leakage into exhaust-valve guide seals, piston rings.

I have 30,000 miles on my 2004 H2, Street miles and well taken care of.
I have crawled under the rig and checked all nuts and bolts for tightness on the exhaust sytem, so no leaks there. I am hearing a rattling sound under the vehicle near the cat when I take off from a stop, or when I power break but then as the rpms climb it goes away, only under a first start load.

What would you do first?

I know I can take it to the dealer and have no worries, my only concern is that these guys always try sticking it in without any lube and it always hurts.
They have no consideration for a mans time.

OEM oxygen sensors are 129.00 dollars each, (2) needed
After market sensors are 59.00 dollars each, (2) needed
Money is not one of my problems so Im not trying to penny pinch but I hate paying top dollar for the exact same part, just a different bag, so what would you do?

Thanks men

Hucky