Intercooler pipe/hose failure

How many miles on the truck?

The Regen timing seems normal. My most recent Regen was at 403. Period to that I've been hovering at around 350.

If you haven't already, replace your MAF sensors. And this may be the result of not monitoring your Regens and likely turning your truck off mid Regen, not allowing it to fully Regen, etc. Over a period of many thousands of miles.

You won't even need an extended warranty for emission stuff, I think emission stuff warranty is 8 years or something like 120k miles.
Just under 30k on the miles. My point was if I delete it, warranty won't cover anything to do with the engine, and the emissions components would be gone. If you Google the code P0421 it says nothing about the MAF sensor, it's all exhaust related components.
 

Just under 30k on the miles. My point was if I delete it, warranty won't cover anything to do with the engine, and the emissions components would be gone. If you Google the code P0421 it says nothing about the MAF sensor, it's all exhaust related components.
It's all connected in one form or another, those sensors trigger all sorts of issues and become very dirty very fast if you never replace or clean them especially at 30k miles.

Try adding something like the Risole DPF clean to your dpf tank and see if that helps but then again you're under warranty so let the dealer handle... And now that you have emissions under monitor never turn off your truck mid Regen, use diesel from reputable gas stations and also use good additives / change your fuel filter regularly

Edit:
Since yours is a 2023, you could also try to force Regen it. Dealer will probably do that first before anything else
 

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It's all connected in one form or another, those sensors trigger all sorts of issues and become very dirty very fast if you never replace or clean them especially at 30k miles.

Try adding something like the Risole DPF clean to your dpf tank and see if that helps but then again you're under warranty so let the dealer handle... And now that you have emissions under monitor never turn off your truck mid Regen, use diesel from reputable gas stations and also use good additives / change your fuel filter regularly

Edit:
Since yours is a 2023, you could also try to force Regen it. Dealer will probably do that first before anything else
I was going to do a manual regen for the last one, but after reading warning page after warning page on the monitor screen I said to hell with it and just went for a 35 mile drive. The warning said you may need to change your oil after a manual regen. Screw that! Does it actually add so much diesel that it bypasses your rings and gets into the crankcase? 🤷‍♂️
 

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I was going to do a manual regen for the last one, but after reading warning page after warning page on the monitor screen I said to help with it and just went for a 35 mile drive. The warning said you may need to change your oil after a manual regen. Screw that! Does it actually add so much diesel that it bypasses your rings and gets into the crankcase? 🤷‍♂️
I can't say I know the answer to that. And my understanding is at least with the banks system is that you can only force Regen at 90% or more.

Maybe if you're forcing a Regen in idle I could see that needing fresh oil afterwards.

When was the last time you did your fuel filter? Do you add additives when you fill up?
 

I can't say I know the answer to that. And my understanding is at least with the banks system is that you can only force Regen at 90% or more.

Maybe if you're forcing a Regen in idle I could see that needing fresh oil afterwards.

When was the last time you did your fuel filter? Do you add additives when you fill up?
I changed the fuel filter on 6-11-24 @ 18,490 miles and I'm at 30k now. The filter wasn't very dirty at all. I have a 2-post hoist in my shop, so my ex son in law always does his service here and his fuel filters get changed at 15k and are always so dirty they're black! He has a 2019 Duramax. He has 175k on it and has only had a NOX sensor failure, no other emissions issues. I just started using Archoil 6400D last time I filled up 10 miles before the last regen started and I kept driving until it finished. That took about 33 miles to complete but did throw that code about half way through it.
 

How many miles on the truck?

The Regen timing seems normal. My most recent Regen was at 403. Period to that I've been hovering at around 350.

If you haven't already, replace your MAF sensors. And this may be the result of not monitoring your Regens and likely turning your truck off mid Regen, not allowing it to fully Regen, etc. Over a period of many thousands of miles.

You won't even need an extended warranty for emission stuff, I think emission stuff warranty is 8 years or something like 120k miles.
Is the 350/400 miles for regen's, you are seeing on a refresh?

My two pre-re's are always over 800 miles!

20241224_090233.webp
 

Is the 350/400 miles for regen's, you are seeing on a refresh?

My two pre-re's are always over 800 miles!

View attachment 23656
Yes I Regen anywhere between 300-400 miles. I don't tow or go on super extended road trips, if I did I think that interval would be majorly extended. Most of my trips are short around town so I try to use my gas alternative and when I have longer highway trips I use the at4.
 

Is the 350/400 miles for regen's, you are seeing on a refresh?

My two pre-re's are always over 800 miles!

View attachment 23656
What year is your AT4? Are you using fuel additives? Archoil claims that I should double my mileage between regens. We will see but I see no difference so far. I'm at about 150 miles and over 70% soot load.
 

What year is your AT4? Are you using fuel additives? Archoil claims that I should double my mileage between regens. We will see but I see no difference so far. I'm at about 150 miles and over 70% soot load.

2023.

I use a bottle of optilube xpd every fill-up, year round and have 50/50 #1 & #2 mix delivered every November.

I also idle a bunch on high idle.
 

Well the saga continues! My truck has has four regens, 3 passive regens in approximately 1200 miles and threw a P0421 code every time. The 3rd regen was a manual regen and no code.....weird! Back to the shop it goes! Researching this it looks like it's either a plugged or defective catalytic converter or a bad sensor. An exhaust leak is another possibility but I have a hoist in my shop at home and I know there are no exhaust leaks.
 

So they finally got my catalytic converter changed, and two seals and one gasket. They said they did another forced regen and took a short drive and no codes thrown. We will see how it goes from here. Since this oil has three forced regens on it, I changed the oil because it was just over the high mark. Not taking any chances. You would think they would have done that. 🤷‍♂️
 

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