420 code...again

Hi Y'all,

I've got a problem. I used some waste fuel that had some diesel mixed in it. Now I'm getting a 420 code that will never go away. Got a 2004 limited V6.

We drain/flushed, replaced both O2 sensors, right side manifold and cat, and muffler.

I can drive anywhere from 8 miles to 100...and got up to 200 during one trip. Any thoughts? My mechanic is stumped.

I hate to goto the stealer-ship....but maybe it's time. I love this truck!

Any help would be great!!!
 
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I don't think they will ever get rid of p0420 since it's the right side that they changed lol. Ironically that's the wrong side, get it? :)
 
When you look at an engine bay from the front of the vehicle the right side would be the drivers side.

OP you should clarify if you mean the drivers side or passengers side cat.
 
I have the URD y-pipe threw a cpl of 0420 replaced both rear sensors haven't had a problem since (insert hand of god here) bam !
 
I have been fighting the dreaded po420 code for along time. First time it came on was when I noticed power loss and visually saw crack in manifold on driver side. Hope that helps on which side. At any rate I decided to remove both manifolds and buy the pacesetters and installed full stainless custom exhaust and replaced all 4 exhaust sensors. A week later after installing pacesetters code flew back in and 3 days later I had a cracked manifold. "Brand new" and cracked 10 days later. Me and my friend removed pacesetter manifold on passenger side this time and noticed extreme blueing on metal which is "high heat". Installed new pacesetter "second" time. Did some ciphering and didn't drive it for a while. So I decided to look at other things that would make the system throw more fuel burning richer. The air flow meter! Replaced the air flow meter and uninstalled my cone filter system in fender well and put stock box back on. No more code for 3 months now. I've put it under heavy pulls with a loaded trailer and all. No more code! Hope this helps someone.
 
I have been fighting the dreaded po420 code for along time. First time it came on was when I noticed power loss and visually saw crack in manifold on driver side. Hope that helps on which side. At any rate I decided to remove both manifolds and buy the pacesetters and installed full stainless custom exhaust and replaced all 4 exhaust sensors. A week later after installing pacesetters code flew back in and 3 days later I had a cracked manifold. "Brand new" and cracked 10 days later. Me and my friend removed pacesetter manifold on passenger side this time and noticed extreme blueing on metal which is "high heat". Installed new pacesetter "second" time. Did some ciphering and didn't drive it for a while. So I decided to look at other things that would make the system throw more fuel burning richer. The air flow meter! Replaced the air flow meter and uninstalled my cone filter system in fender well and put stock box back on. No more code for 3 months now. I've put it under heavy pulls with a loaded trailer and all. No more code! Hope this helps someone.

You mean MAF sensor?
 
Older toys used an air flow meter im guilty of calling the maf that too but to the op make sure the correct side was changed p0420 is bank 1 or the side with cyl 1 in it the easiest way to tell which is which without looking it up is to see which spark plug is farther forward (toward radiator) that is bank 1. The MAF sensor is known to cause cat efficiency codes if its dirty or malfunctioning. Try pulling it out and cleaning it with brake clean or carb clean there is a tiny wire heating element that gets dirty and will produce an improper signal back to the pcm
 
Ok, but who refers to it like that? Usually it's orientation from drivers seat right

I got mine for $160 each well it ended up being $0.60 per tire from rebates! They are the BEST tires in the world, will climb Everest mounted inside out, spinning on the wheel the whole way up! They also will flip out and fly with the Mr. Fusion I installed from back to the future! BFG KO's are so bad the vehicle rips the tires off by itself, bare wheels are better in mud and snow!!!!!
 
Wong thread buddy! But I get it lol. Thanks for making me laugh so hard I woke my wife up and now she pissed at me cause she gots to be up at 5am hahaha
 
Wong thread buddy! But I get it lol. Thanks for making me laugh so hard I woke my wife up and now she pissed at me cause she gots to be up at 5am hahaha

Wrong thread was intentional!! Made the laugh better, I'm sure some were like WTF! Anyway, tell her to get some AT3's and life will be better!
 
Lol, oh she is getting more and more pissed. I am laughing and grinning and she's doing the blanket pulling tussle right now with a huuumpfff sigh to back it up. Dude is always right and bragging about his 100 tires.
 
Crap!!!

thanks guys. I thought so but apparently the repair manual says the V6 and V8 versions contradict each other. Thus the problem.

Again, thanks for your help!!! I guess I'll go out and get driver's side cats.
 
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and just to clarify the banks on a 4.0 v6 1grfe bank 1 is the passenger side or right side on the 4.7l v8 2uzfe bank 1 is the drivers side or left side at least in the usa
 

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