MPX1

Yep. I went with the info I had at the time. It looked like this issue had dragged on for a while and my GM dealer's response didn't give me a ton of hope. I couldn't have a car in the shop for a few weeks and no loaner. Maybe next time, GM. Maybe next time...

Figured I'd wrap this one up - ended up utilizing the insane trade-in values we're experiencing right now and I got out of my AT4 about 6 weeks ago. Sad day. I got a tad more than I paid for it in the trade so that was good, but after I posted about experiencing my first no-start, they started happening multiple times per week. GM said they'd have to keep the truck for a few weeks, had no loaners, were short on techs and parts, etc etc. I can't be down a vehicle while they try to figure this thing out. Hope GM figures out the 3.0L issues because it's a really great truck and that motor is incredible. Just can't have a vehicle that doesn't start randomly.

Def worth posting that. Good stuff

Alright so my "great so far" ended today. 4700 miles and had a no-start crank this morning during a remote start. I posted the details on the main thread on this forum where people seem to be keeping an eye on this issue. I jumped in the truck immediately and saw a message on the DIC that said something to the effect of "service steering column." I only saw it for a split second before it disappeared so that definitely isn't exactly what it said, but that's the best I can recall. It started immediately afterward and has started fine the rest of the day. Add my truck to the list of trucks with this issue apparently....

Hey guys - 2021 Sierra AT4 here purchased in April of 2021. I have 4700 miles on the truck and just had a no-start for the first time this morning, but it was during a remote start. I immediately opened the door and looked at the DIC and saw a message that said something to the effect of "service steering column" before it disappeared. Sorry that I don't have the exact message. I got a half-second glimpse of it before it went away and never came back. Truck turned over instantly afterward when I pressed the start button. I've read all 21 pages of this thread and it looks like this issue is still a ghost. Does that sound about right? Good on all of you for doing God's work here and trying to figure this thing out. Would be better if GM would just do it.

Wanted to update - 3700 miles after a 1200-ish mile road trip last week. I know I'm still very early in the ownership period for this truck, but if I wasn't 100% sold on the 3.0 Duramax before my long trip, I am now. I honestly can't say enough positive things about this powertrain, not to mention the AT4 itself. Truck was loaded up with my wife and daughter and the dog and a bed full of luggage and gear. On the way out to the Carolinas via I-40, I hand-calculated 27 mpg. I usually try to keep between 70-80 on the highway. My best 50 mile run was 38 mpg, with the worst being about 22 and that was during a stint of driving...uh...fast. Haha. Zero issues, diesel is an absolute beast. TONS of passing ability on the highway which surprised me. It won't put you in the back of the seat like maybe the 6.2 would, but it's more than enough. They really found a way to make this engine sing at all speeds. Extremely comfortable, and the camera system was clutch in the mountains. Getting into and out of tight spaces where a wrong move could send a corner of the vehicle over a ledge was made stupid easy with the cameras. Love this truck.

Late reply here, but yeah same - 210. Kind of floats around that. I've noticed during regens that it'll kick a notch higher here and there and then settle back down to 210 when it's done. This thing is going on some long road trips in the next few months so I'll have a lot of mileage to report. Still great though at 1700 miles. No issues.

Since most forum posts consist of folks' negative experiences with anything and everything, I figured I'd post about my positive experience with the 3.0 Duramax up to this point. Granted, I haven't had it long. I've put about 1000 miles on it - most of that has been city driving. Lots of short trips, idling, etc. A few highway drives here and there. I've had zero issues with the truck or the engine up to this point. It seems like a lot of the posts here show issues with the Duramax within the first 1000 miles or so (throwing codes, trips to the dealer for xyz, on and on). It drives incredibly well and has even seemed to smooth out and drive better past the early break-in period. For prospective buyers of the 3.0 - this likely won't go over well with the traditional diesel guys, but don't listen to them. Old-school (and even some "newer" school) diesel rules don't really apply to this engine. If you look at the design, it was built with the daily driver in mind. Being that the exhaust system has always been an issue for diesel trucks built over the last decade or more, it seems that GM went out of their way to make that mostly a non-issue on this truck. The engine is small, so it doesn't take long to get up to temp. Combining the DPF and the SCR into one unit and placing it next to the engine makes it far more efficient and exposes it to more heat more often. In my first thousand miles, I've only noticed one regen (I'm not using a OBD to track...I don't care to get that granular). It's likely had more than one, but I've only "noticed" one. AND...it occurred over multiple short trips around town. It completed on its own with no issues. There was a day where I had to bounce around town and do a bunch of ******, and over the course of a couple hours and probably 6-7 destinations with tons of stop and go, the regen ran through the cycle and completed on its own. No problem. I'm sure plenty of diesel guys will show up here and tell me how wrong I am and how I'm asking for issues, but keep in mind - GM is putting this engine in a bunch of family cars and heavily incentivizing people to move in that direction (no-cost upgrade on the Escalade, $995 on most other vehicles). Being that this is one of the few diesel engines in America that wasn't sourced from a European manufacturer and repurposed for the US (clean sheet design, etc), it seems like GM really put a ton of effort into figuring out the exhaust system issues. Being that warranty repairs cost the manufacturer money, it doesn't make a ton of sense that they'd put these in cars that would idle a ton and be subjected to stop-and-go traffic if it were going to cause a boatload of issues. People freaked out back in the day when gas engines were forced to use catalytic converters and such. Eventually, manufacturers figured it out and now they're a non-issue. I feel like this engine has been a big step in that direction for diesel. I may eat crow and come back here cursing myself for purchasing the diesel down the road, but so far it's been great and I couldn't be happier with this truck. It's an absolute joy to drive on a daily basis. I'll keep this thread updated as my ownership progresses.