SoDakAT4X
New member
I am contemplating giving up on my AT4X order after 12 months of waiting for it to arrive. I am now considering an AT4 Diesel. I know about it’s fuel economy but how is the power, towing and reliability?
Duramax LZO how does everyone like this engine?
- Thread starter SoDakAT4X
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casshed
New member
I got the 2023 AT4 diesel, love the MPG, definitely comes with a few extra things to maintain but overall I like it. Put over 3k miles on it and haven’t had any starting issues, even in below 0 temps. With that said, it’s currently at the dealer for a repeated check engine light… App said to check emissions system, dealer code reader says it’s a NOx sensor performance error, always the same one. Dealer is working with GM to see if it’s the computer or sensor… the fun begins, hopefully it doesn’t end like the 22 tundra I got rid of. I haven’t read of others having this issue fortunately.
Cocoabean
Well-known member
@casshed I have the LM2 motor and mine had to go to the dealer for 2 check engine lights for emissions. One was a loose intake clamp and the second was a NOx sensor not being seared correctly. They had to get GM engineering involved to track down the NOx sensor being unseated. Once corrected I haven’t had anymore issues.
Hopefully yours is just as simple.
Hopefully yours is just as simple.
I just traded off my 2020 AT4 with the 3.0 diesel. I loved the truck and engine, but about a month ago the "service emissions system" warning popped up. First fix they replaced a cylinder head sensor, which cost $600 to replace a $30 sensor. Drove the truck about 200 miles and the same warning popped up on my dash again. This of course puts the truck in limp mode, which is unacceptable. Had the truck at the dealer for over a week on the 2nd go around, they said it was 3 sensors for the emissions system and said it would be at least a grand to fix this time. Some BS in my opinion for 3 sensors.
I have been working out of state much of this past year, and with no driveable truck to get me home on the 1000 mile trip from Nebraska to Montana, and the dealer not being able to fix the problem, I decided to trade the truck for a new 2023 AT4X with the 6.2 the dealer just got off the semi. Love the new truck, the gas mileage sucks on the 6.2 (averaged about 15 mpg on the trip back to Montana), but with the difference in price between gas and diesel I may still come out ahead in the pocket book with the 6.2 for fuel costs. Seems this same warning code has been popping up for people regularly with the 3.0 diesel and I can't afford to be stranded with no driveable truck. It is a great little engine with lots of torque, but likely to be finicky long term possibly. I had never had a problem with it up to this point (39 K miles) and even 20+ below temps in the winter in Montana it started up fine. But it had to go as I had lost confidence GM could actually get the problem figured out.
I have been working out of state much of this past year, and with no driveable truck to get me home on the 1000 mile trip from Nebraska to Montana, and the dealer not being able to fix the problem, I decided to trade the truck for a new 2023 AT4X with the 6.2 the dealer just got off the semi. Love the new truck, the gas mileage sucks on the 6.2 (averaged about 15 mpg on the trip back to Montana), but with the difference in price between gas and diesel I may still come out ahead in the pocket book with the 6.2 for fuel costs. Seems this same warning code has been popping up for people regularly with the 3.0 diesel and I can't afford to be stranded with no driveable truck. It is a great little engine with lots of torque, but likely to be finicky long term possibly. I had never had a problem with it up to this point (39 K miles) and even 20+ below temps in the winter in Montana it started up fine. But it had to go as I had lost confidence GM could actually get the problem figured out.
Wickstick7
New member
That’s funny you say that. I just picked up my 2023 3.0 two weeks ago today. Drove it from Michigan down to Florida so it now has 1700 miles… check engine light came on to service engine/transmission within 7 days….the next day it says service DEF system and in 90 miles my speed will be reduced to 65mph… wtf.
Called a couple dealers and they have nothing available. One even suggested I don’t drive it because the motor would blow, and to tow it. Brand new vehicle! Never had a check engine light in my life with Ford or Ram. I just hope I am not going back and forth 1000x with no fix.
Yep, from my online research when my 2020 AT4 with the 3.0 started having these problems a little over a month ago, I had the same issues. Problem is, there is a parts shortage, so most dealers need to call other dealers to see who might have the sensors in stock, then order/ship the sensor from the other dealer. But on mine, replacing a sensor did not fix the problem as the same warning code came up on the dash 200 miles later.
2nd time around, they said it was 3 different sensors they were going to replace this time. But they were having a hard time finding the sensors. I simply lost faith this problem wasn't going to be a continuous one ongoing, and once a comparable truck arrived at the dealer mine was at for this issue, I decided to trade it off. I got really good $ in trade for mine and a deep discount on the new truck, plus I didn't have to pay for the pending repair bills on my truck I was trading.
GM needs to get this figured out. The 3.0 diesel is a really nice engine, but issues like this common warning code popping up putting the truck into limp mode, and the difficulty in being able to diagnose and actually fix the problem, is not acceptable. I simply could wait no longer for the truck to be fixed of this issue. I am hoping this new AT4X and the 6.2 does not have similar problems. The diesel is a more complicated engine and with the DEF and emissions system I believe it is likely to have more of these types of issues.
I do so far like the 6.2 engine. It has great power and is fun to drive. I only wish they had put in a 28 gallon tank as the range on the 6.2 gas is maybe 400 miles tops if you are driving it with a light foot. On my 1000 mile trip back and forth from Montana (where I have lived these past 22 years) and Nebraska (where I am from and go to visit family and sometimes do jobs), I was able to at times only stop once for a fill up at the halfway point with the 3.0 diesel (really depended on the road conditions and if a prevailing head wind was cutting into fuel mileage). On the 6.2 AT4X I had to stop 3 times for a fill up, although I didn't start with a full tank (maybe at 3/4) and I ended with about a half tank left on the trip. It simply needs a bigger gas tank getting 14 to 15 mpg on the interstate heading west into prevailing head winds.
Andystoy AT4
Active member
Not much info on the LZO as per your initial post, I have a 2022 refreshed AT4 LM2 which was delivered in early June, very good fuel mileage, tows light loads well (5000 lbs) and 5000 miles on the truck. I traded from a 2016 6.0 gas; I have no reason to look back and no problems so far.
Have a 2022 AT4 Diesel, best truck I have ever owned. It jumps out of the hole, fuel economy is good. I have not towed anything heavy yet. Great truck engine/tranny combo
Cocoabean
Well-known member
@Mazie Dog said it well. I really enjoy the power and mpg of the LM2. I had minor CEL issue for emissions, but other than that I love this truck. Obviously this set up has a different purpose than the AT4X with a 6.2, so only you can decide which set up makes more sense for you.
Wickstick7
New member
So I took my truck to the dealer the day after my check engine light (Wednesday) …. 2hrs in they said it possibly could be the DEF control module and they would have to order a nationally backordered part. So I get put in a rental…. Fast forward to today (Saturday), they said they got the part in and was going to replace it. The mechanic said he hopes this fixes the problem because the DEF is not communicating with the truck. So now I am waiting until Monday or Tuesday to hear back from the dealer to see if the problem is fixed.
I just hope it’s not all these sensors they have to diagnose through like you did. This really lowers my confidence in the truck when going on longer trips with the family. I can’t afford the truck just a shut down hundreds of miles away from home.
Roger Helzer
New member
I own a 2020 AT4 Diesel w 36K miles. No issues, great mileage, and plenty of power.
TB_Rider
Member
2022 Refresh LM2. 5.5K and no issues so far. Awesome mileage. Tows much better than my 5.3 even though it is less HP.
Man, sorry to hear you are having these issues! And sounds familiar, as I actually traded mine away so that I had something not in the shop for a month. And who knows if spending all this money even fixes the problem. Kind of a mess, and GM should be on top of this better IMO. I had lost all confidence that the truck would be fixed and not go into limp mode 200 miles from home stranding me. Seeing as I needed to make a 1000 mile trip between NE and MT, did not want to get stranded in that area of the country in the winter.
I hope your situation gets fixed right, quickly!
