Anyone else ran into these Check engine code problems on 22 gmc sierra at4

IDK what those codes are, but I had continual "service emissions system" error codes on my 2020 AT4 3.0. Forced me to trade it off as the dealership could never figure it out or fix it. I am guessing those are similar codes in your post to what my AT4 diesel was throwing.

Now I have a nicer 2023 AT4X... but miss the 20+ MPG the baby diesel got. 6.2 is thirsty. But costs about the same, probably less, in the pocketbook per mile driven as gas is that much cheaper than diesel. Just a lot shorter range on the 24 gallon tank on the 6.2, it needs at least a 28 gallon tank. 500+ mile range on the 3.0 on the hwy easy on the 24 gallon tank... at times pushing 600 mile range. would be really pushing it towards E to get 375 mile range on my 6.2 AT4X.
 

I totally agree, the small tank sux! Go on a long trip, better add sometime to get there cause of extra gas stop.
 

My check engine light went away and so I called the dealership and they said it's an update didnt know these sierras did that.
 

My check engine light on a 2022 3.0 duramax came on at about 3000k miles , stayed for a week then left. I never had it read .
 

2022 AT4 3.0 -Not sure of my code number- Had issues the first 5000 miles. 3 times into 2 Dealerships could not figure it out. GMC sent engineers out and started taking the emissions apart piece by piece smoke testing Cat forward and intake back Found back pressure valve leaking at the flanges. Replaced the entire assembly. No problems next 7000 miles later.
 

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2022 AT4 3.0 -Not sure of my code number- Had issues the first 5000 miles. 3 times into 2 Dealerships could not figure it out. GMC sent engineers out and started taking the emissions apart piece by piece smoke testing Cat forward and intake back Found back pressure valve leaking at the flanges. Replaced the entire assembly. No problems next 7000 miles later.
Check engine came on 2500miles in. Came on a week ago, went away on its own. This week, boom light back on. This time the app states emission system. I took it to the dealer they believe the Cat is shot. “Testing” tomorrow. Been told it’s no big deal to drive on, yet other day while in traffic my truck out shuts off then didn’t turn back on lol. Hit both pedals. Nothing. Turned truck off then back on. Hadn’t happened again.
 

Sorry to read about these continual baby diesel problems. I loved my 2020 AT4 3.0, but when it was unfixed after a month in the dealership, stranding me for an extra month (was already gone for 4 weeks already as I was working out of state) with no fix in sight, I had to trade it.

GM needs to figure this crap out. I considered a 2023 AT4 HD diesel, but was reading about the similar issues with those also. Could have bought a 23 AT4 HD for almost the same price (probably a bit more expensive) than my 2023 AT4X, but I think I am done with GM diesels. Would love the have that 6.7 ltr AT4 diesel, its torque, power and yes, improved fuel mileage over my 6.2 AT4X (I do love the 6.2 but it is thirsty), but just don't need the headache of more possible issues with a more complicated fuel/emissions system that these diesels require. Hope those here with AT4 diesels are able to get GM to figure this crap out. It seems to happen to frequently, and often the same or similar issues people are having.
 

Those are definitely emission issue codes. I finally traded in my 3.0 diesel after having in the shop in and off for over a year. I’m that time they changed 3 sensors, every glow plug and finally a transmission component. The transmission problem was caused by the rough running, caused by the emission issues. Get it to the dealership while under warranty and ask them to check everything while they have it.
I loved the 3.0 for gas mileage and how quiet it was , but could not offers to be without a truck. Stepped up to the AT4 with the 6.2 diesel. It is a beast, but is “thirsty” as described in a earlier response.
 

Just picked up a GAP tool to see what i can see prior to dropping it off at the dealer this afternoon. The dealer has been less than helpful as I await a new back up camera due to lack of functionality while in use as well as parking sensor retrofit.
 

Dealerships were not very helpful until I got GMC customer service involved. My call was to start a log with then to be able to return the truck. After that the dealership had a better response. Also want to note that the first replacement pressure valve was defected as well. Multiply Service Reps from the different dealership were very pessimistic about the truck leading me to believe it was related to the burn-off part of the process and I should drive the truck down the freeway for 40 miles per tank when the truck was going thru it’s process. WTF..Thats when I got customer service involved. They called BS on it and flew their engineers out to diagnose the truck. Very happy with GMC Customer Service. Love this truck. Hope the problem is solved.
 

Dealerships were not very helpful until I got GMC customer service involved. My call was to start a log with then to be able to return the truck. After that the dealership had a better response. Also want to note that the first replacement pressure valve was defected as well. Multiply Service Reps from the different dealership were very pessimistic about the truck leading me to believe it was related to the burn-off part of the process and I should drive the truck down the freeway for 40 miles per tank when the truck was going thru it’s process. WTF..Thats when I got customer service involved. They called BS on it and flew their engineers out to diagnose the truck. Very happy with GMC Customer Service. Love this truck. Hope the problem is solved.
How did you get a hold of customer service? I have a 23 AT4 with a reoccurring NOx sensor issue (P22FE). Dealer replaced a sensor first, then a wiring harness but CEL just came back on. We called what I think is GM customer service and they basically said they can just schedule us an appointment with the dealer to look at it again.
 

How did you get a hold of customer service? I have a 23 AT4 with a reoccurring NOx sensor issue (P22FE). Dealer replaced a sensor first, then a wiring harness but CEL just came back on. We called what I think is GM customer service and they basically said they can just schedule us an appointment with the dealer to look at it again.
866.790-5600
 

2022 AT4 3.0 -Not sure of my code number- Had issues the first 5000 miles. 3 times into 2 Dealerships could not figure it out. GMC sent engineers out and started taking the emissions apart piece by piece smoke testing Cat forward and intake back Found back pressure valve leaking at the flanges. Replaced the entire assembly. No problems next 7000 miles later.
Jinxed myself. Lights on, will be getting in touch with GMC tomorrow.
 

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