EngineNoO9

I have a 2022 suburban Premier with the LM2 diesel. VIN: 1GNSKFKT0NR331751 Current Mileage: 82000 Right out of the gate we had some initial problems with it as it drank 5+ quarts of oil in the first 2-3000 miles off of the showroom floor. Didn't discover it until we accelerated and it threw a low oil pressure code. Dealer was great and worked with us and finally figured out that somehow despite our valve cover having the correct part number based on a TSB, it was the old part that was having excessive oil consumption (likely vacuum). So they replaced that and one glow plug that went out and that specific issue has been fine ever since. Only throwing this issue in there as it's how we started out with this vehicle and it resulted in the dealer giving us a 120000 mile extended warranty. Absolutely love it though. So we don't tow often with this vehicle and before 50,000 miles the only thing we towed is our pontoon boat which is maybe 2500 lbs. So nothing.... Around 50,000 miles we suffered our first transmission issue. We were driving home towing the pontoon on a flat road going a steady speed of 55 mph and suddenly the vehicle shook really hard like I ran over a really hard transition in the road but it kind've felt like the boat was pulling me back really hard. And then it did it again about 5 seconds later. I pulled over thinking I had a problem with my trailer and couldn't find anything wrong. Drove home without issue and shortly after this got the transmission flushed. After this event we bought a travel trailer and never once had an issue while towing it. At around 60,000 miles we were driving up a mountain going a steady speed of 35mph with all of my kids in the car and the vehicle did the same thing as before. Shook violently 2 times in a row. Pulled over, got real nervous as we had a long ways to go to continue going up the mountain so we turned around. Took it to a Chevy dealer that was local to where we were on vacation and they couldn't find anything wrong. Suburban finished the trip without issue. Maybe 6 months later it did it again but it was while towing a lightweight utility trailer with a single sportbike (total weight of maybe 1500 lbs) on it going steady speed of 50mph. Difference was it did it just once. Shook violently. Then it did it 2-3 more times in a 5 - 10 minute span before I was able to safely pull off of the highway. I cycle power and it seemed to go away after that as I had another 2 hrs to drive home. Around this time I contacted a local dealership and explained the problem and they started working with me to help troubleshoot since it couldn't be replicated. They updated the TCM software and said if it happened again I'd likely be looking at a new valve body. This was last fall in 2025. Right around Christmas the vehicle did the violent shifts again 4-5 times at different speeds and we drove straight to the dealer since we were in town. Dealer confirmed they'd be ordering a valve body and we'd have to wait for it to show up. About a week or two later before the valve body showed up I was driving my kids to town and it did it again. But this time the vehicle was struggling to find a gear and was lurching real bad. I thought the vehicle was actually gonna die on me. It eventually threw a couple codes and limited my speed. Code was: P0336. Limped it to the dealer about a week before the valve body showed up and left it there. Got the valve body replaced at 77,000 miles and only noted issues were during the learn period it shifted rough but I assumed it was 100% related to the learning (mechanic told me don't be alarmed by this). After about a month of a good mix of driving at city and highway speeds we never had an issue. 5000 miles later now at 82000 miles and about 4 months, its started shifting hard randomly. Kids will ask did we hit something or did someone rear end the car. It's happened in 2 different scenarios where once it was accelerating lightly away from a light and the other with cruise control on going 50 mph. Currently have an appt to drop it off on Monday but not expecting much other than we'll keep an eye on it. Not once has the vehicle actually thrown a TCM code, and it's been a-typical to what I've found online. The P0336 issue for instance, the best we can assume is because the valve body was searching for a gear that the engine in turn threw a code because the transmission was basically making it run super rough. I know this is long winded but I'm at the point that I'm losing confidence in this vehicle being my wife's vehicle to take the kids around in. I could care less if it breaks while I'm in it but I don't want her getting stuck in it with all of my kids. I did ask the dealer about a full trans replacement and it seems that they're hesitant to do that unless they find metal or that the fluid looks bad. So not holding my breath.... Also wondering if we're chasing the wrong thing entirely and need to look more at the crankshaft position sensor (P0336) and see if there's a chafed wire or bad connection, etc. Any help is appreciated. ~Joe

I agree but all we’ve gotten so far is them taking it for a test drive and nothing. I’m gonna push the service dept for something more.

I assume so but it’s not the same year as they have in the existing TSB. They can’t at March 2022 build date but mine is June 2022. Though I explained to GM that my camshaft cover had an updated part number but was the original design that caused major oil consumption issues. Dealer had to work direct with GM engineers to determine that and correct. So clearly there’s some overlap on parts.

At a loss and frustrated. Our 2022 suburban is great and we love it. However, I’ve had lock up issues now 3 separate times over a year. At first I thought it was an issue with my boat trailer. Then it happened again and I got to reading more. It lines up perfectly to what’s described in the wheel lock up recall. It’s so random that a dealer can’t find anything too. We had the trans flushed at 50,000 miles after the first incident and I was hoping that may cure it. It’s also happened when towing and not towing, and happened at different speeds. Trying to figure out my next play as the recall to add software doesn’t include my vehicle as it’s a 2022 vs a 2021. Now to me, an engineer; it seems silly not to do the recall on all diesel years as it’s only a software patch to detect potential failure. But of course that’s getting me nowhere. I tried calling GM customer satisfaction and that was a waste of time. Likely going to install a dash cam to hopefully catch video when it happens again (vehicle violently shakes with a loud bump noise) but that’s my only play right now. Selling isn’t really an option as the market sucks and getting a model year newer with same options just won’t happen without decent money out of pocket. I guess eventually we may have to look closer at this option if we can’t get it figured out. I am going to chat with a friend of a friend that’s a mechanic at a Cadillac dealer to get his opinion on the issue. But basically kindve stuck. Anyone else actually had this happen? It’s not a hard shift or anything. It has happened when driving steady speed (not towing going up a mountain at 35 mph, towing a boat ~2500 lbs going 60 mph, towing a utility trailer with a motorcycle on it ~1500 lbs at 60 mph). -Frustrated

So I’ve been a life long GM owner and do as much maintenance as I can myself. We currently own my old 2007 Avalanche with 240k on it and a newer 2022 suburban with the 3.0l diesel. Looking to get myself a new to me vehicle and I was originally eyeballing a a 2018-2020 GMC Denali to get the 10 spd but some friends of ours just fried their 2018 Denali’s 10 spd for a rather spicy repair bill. So now I’m kicking around maybe going with a Tahoe or non Denali maybe a little older with the 5.3l and finding a 6 spd and getting the converter preemptively swapped out (we had a 2013 suburban that the converter went out on and fried the trans at like 120k so very familiar with that). Haven’t seen a lot on the 8 spd other than removing the coolant bypass helps…. So for someone using this as a backup family vehicle and commuting to work, what would be the thoughts on which transmission would you recommend? For the record we’ve had a few hiccups on our 2022 10 spd which makes me nervous. Only saving grace there is it’s still under warranty for now. And I don’t care much for gas mileage improvement on a 10 spd if that’s the only upside. I’ll immediately disable AFM/DFM on whatever I get too.

So does anyone know what the software push is actually doing? Just got notice for our suburban. Says we have to go to a dealer for it.

Have a 2022 Suburban Premier with the automatic running boards and we had the software fix put in place a year ago to correct issues where the passenger one wouldn't deploy all the time. Now my wife and kids are on vacation and she told me the passenger side one keeps retracting and deploying while driving. Anyone else seen this? She said she didn't see anything jammed in the linkage and they really aren't even dirty outside of normal driving. Thinking maybe its a sensor that tells when it's fully retracted may be bad? Any thoughts? Won't have a chance to take it to a dealer until later. She even tried disabling automatic deploying and it was still flipping out so they pulled the fuse for now. Getting tired of the running boards being a problem....

Ours has the updated camshaft housing and they replaced it with the same exact one. They’d said they were hoping for a leak as that’s be easier to explain. The glow plug issue was tied to the camshaft housing cover TSB. Glow Plug #2.

we’ve had 3400 trouble miles with multiple CELs but all related to the same issue. Driveability and mileage has been great. Not really following what you’re saying about stories. As an engineer the PCV seems to be the only thing that makes sense but that’s us just bs’ing cause both parties are frustrated. They’ve had to bend over backwards to try and help us out in a vehicle that shouldn’t need any work. They want to avoid a buyback as much as we do but I also draw a line in the sand with a full motor swap on a vehicle this new that I paid that much for. Talking with the Service Director (2nd only to the GM), he’s been very up front to us. The techs had never done this job before and have definitely never engine swapped. Doesn’t make me feel warm and fuzzy. Unfortunately the engineers at GM aren’t saying anything either but it appears that whatever is wrong in our specific motor is definitely a fluke.

My ‘07 avalanche with the 5.3 has 210,000 miles on it and maybe burns a qt every 5000 miles. Mostly if I heavy highway drive. It is what it is. The diesel doesn’t have AFM. They seem to be grasping at straws though the thought is there’s something with the PCV. Maybe…

Bought a brand new 2022 suburban with the 3.0 duramax in July and we’ve had major oil consumption issues. At 1500 miles it was down 4.5 quarts and the low oil pressure code got thrown. Initial assumption was the dealer may have forgotten to check oil at the pre delivery inspection. Did an oil consumption test and at 700 miles we were at 2.5 quarts down. Dealer is working with GM and they replaced the camshaft housing cover even though it already has the “updated” one. It also fried the number 2 glow plug which was replaced. The service director seems doubtful that the “fix” Will correct the issue. From what we’re being told they haven’t seen this on the corrected camshaft housing covers. Our dealer had never even replaced one before. If it fails the next oil consumption test we’re likely looking at buyback. I told them I don’t want a new motor. Not for as much as this cost. I’d rather start over at zero. Anyone else see this level of oil consumption? We love the diesel and will likely get that option again. Just frustrated with this one.

Got my answer. Was told they’d just replace everything out of precaution as they don’t know what the trans May or may not have digested so far. It sounds like it could be salvageable but not worth the fuss when throwing in a reman. $4-5k repair…. Ouch!

So question, if your trans is starting to do the bucking/slipping and fluid is burnt, is the trans salvageable or is it toast at that point? My suburban just started and was gonna take it in. Shop has been in business since 1971 so they know they’re stuff but curious if there’s any hope of not replacing the whole thing.