Oldblue

Well this trip, let it rip , for 100 miles, then turn around and drive back, not 50 miles then turn around!
No need to ask how I know!

SheckyB

Hey, Blue How are you doing? I have been here Before Pecking at My Engine Light I was Getting All Kinds Of Codes every time I fix something Boom the light Goes right back on I finally got it down to 1 Code PO420. I Did not put a factory Catalytic Converter Back in Now its saying That could be the reason for the Code or 02 sensors are bad I just put in 2 new ACDelco 02 sensors I Checked temperature through the Exhaust and it varied a lot Is this a problem To drive around With Being I know everything was Changed or do I need to throw away a new Cat because it is not Factory Or Live with the light? What Do Ya Think??

Oldblue

What cat did you purchase?
Did you check the connectors to the O2 sensors?
have you tried a battery lobotomy?
check for exhaust leaks prior to the cat perhaps the gasket blew out!

https://www.obd-codes.com/p0420

SheckyB

I purchased an aftermarket Catalytic Converter 2 new ACDelco 02 sensors it started with PO171 Checked for leaks None. Changed Fuel rail fuel injectors plugs and coils gas Cap and anything else I was told to and Always another code Now PO420 I'm pretty sure the Cat is not clogged It's New! And that's all Dam light just wants to stay on...Lol

RJ_RS_SS_350

Since the P0420 occurred after you replaced parts, that's where you should be looking. Start by testing the o2 sensors and connections.

SheckyB

When I unplugged the o2 sensor there was oil by the connection stuck some Qtip in there to try and dry it got what I could out I had a hard time getting in there Could that Effect it?

Oldblue

Yes, take that connector apart and spray it with contact cleaner, Ensure there are no bent pins, then apply some dielectric grease and reconnect it