The ole' P0420 code...

I installed some TRD headers and a Magnaflow Catback exhaust about a month ago and drove from Dallas to Louisiana for work. No issues, the truck sat for three weeks and I just drove it today and my Scan Gauge alarmed the P0420 code. Not long after that my check engine light came on. So far this is what I'm thinking...

1) I had used some red RTV (non o2 sensor safe) on the Catback exhaust flanges but being that there are no sensors after the cats I've ruled that out.

2) I had to cut my cat so that it would line up with the y-pipe to the headers and possibly some of the metal shavings are causing the code but being that I drove 8 hours without an issue I've pretty much ruled that out. Also, we had to weld a two bolt flange onto the piping so that I could bolt it to the y-pipe so possibly some slag got into the cat? (Not sure about this because it was a shop that did the welding)

3) the o2 sensor that was on the cat pipe was cut off along with the piping but the y-pipe that came with the headers had a similar location and even though it was a tight fit we got the o2 sensor in there with a very little bit of play in the wire. It wasn't super tight but I wish the wire had a bit more play than it had.
This may be an issue and haven't got under the truck as of yet to see if the wire is possibly the culprit.

4) or my cats are 14 years old and need replacing?

What's the best method to troubleshoot this?

I'm still in Louisiana and crew change is in 10 days. Would I be ok to drive home eight hours or should I bring it to a shop?

 

You're fine to drive it, you're just polluting more. I'm banking on option 2 or 4. You could have messed the cat up or it could just be old. If you're going to keep modding your engine, just get the URD simulator. At ~$100 it's cheaper than new cats

 

I have an easy fix. Buy an aftermarket spun high flow cat and trash both the old ones. I cut the pipe right at the collector collar at the base of headers and welded on a 3" pipe into a single cat then to a series 40 flowmaster for some real sound! Make sure the rear o2 sensor bung is exactly the same distance as the factory set up from the back of the cat.

 

Can you shoot me a sound clip whenever you get the chance? I like how it sounds now but would like a little more of a rumble to it.

 

https://youtu.be/mSqMcKw9Gt4

 

Thanks, In a perfect world I'd like to just buy two MF cats and call it a day but that's like $800+. I just put a little over $1k in the headers and Catback exhaust. Trying to save for a house the URD simulator makes a lot more sense to my wallet

 

That's sounds sweet dude!