So I threw a P0420 code today. I think it has to do with my gutted cat. I have a new front o2 sensor also. I gutted the cat 2 months ago and it just threw the code. I thought that was kinda weird. Any advice? Thanks

clear it and get an O2 sim.

www.thefastman.com

O2 sim or replace the cat.
I'm very surprised more people don't have this code with the converter removed.

I had mine gutted out a couple weeks ago until I could get a Magnaflow hi-flo to go on my truck and I still have no check engine light.

+1, I am surprised as well.

i gutted mine like a year ago, and havent had any codes, i also passed ct emissions testing.

It's obvious that the Ram PCM programing isn't very sensitive to converter efficiency.
It's strange they (Chrysler)can get away with it on these models.
It's great for you guys that cut out the converter but the system isn't working the way it is supposed to.
I know guys with Jeeps of the same years and the MIL light comes on within minutes if the cat is removed.

Goldpro, do they actually test up the tailpipe in your state? Or is it just avisual / scanner test?

tail pipe, they put it on like a dyno and run it up to speed and crap.

Interesting....

Oh wait, your trucks are 3/4 tons. The specs are way lower (practically non existent) in most states for 3/4 and heavier trucks

The cat just burns excess gas correct?

if you're engine's running tip top, you shouldn't have a whole lot of excess gas. You add a few engine mods to these thing and they start running a tad lean anyways.