general problems of the 2021 GMC Sierra 1500 - part 2

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 45 mph, the transmission inadvertently shifted from drive (d) to first gear. The check engine warning light was illuminated. The vehicle was pulled over to the side of the road and then towed to the dealer, where it was diagnosed, and it was determined that the valve body needed to be replaced. The vehicle was not repaired because parts were not available. The manufacturer was notified of the failure. The failure mileage was approximately 103,000.

Loss of power code p0016 now truck won't start.

At 22,000 miles I experienced issues while driving on a 150 mile trip. We frequently take this particular drive. We choose to driver later in the evening to miss commuter traffic. This even we pull over for a late dinner and hear a loud ticking noise while the the truck seems to lose power. I turn the vehicle off and start it again and its worse, it barely idols and shuts down. I'm in a parking lot and drive down the block to a gas station where serves only gas and no mechanics onsite. I turn off the car and wait 5 mins and restart, same results but this time all the warning lights come on. We end up finding a hotel and in the morning I find a Chevrolet dealership down the block, I ask if I can take it in, there the advisor connects to my obd port and says there are many issues and needs to see a mechanic. I manage to get it towed 80's to the original dealership. Advisor says the engine is bad and replaces it. Now my vehicle has 38,000 miles and I run into the same issue, loud ticking sounds and low power. Immediately I drive it home and the next day have it towed to the dealership to have it looked at. The advisor said during their analysis they saw metal in the air filter so another engine has to ordered and installed.

On the afternoon of 01/20/26, I was merging onto the highway in my 2021 GMC Sierra 1500 when a loud bang was heard from the engine compartment at approximately 60 mph. Immediately after the ban was heard, several indicator lights on the dashboard were illuminated, including the esc, check engine light, and parking brake light. A power loss was felt when attempting to accelerate and the banging noise worsened anytime the accelerator was depressed. I was able to drive the vehicle to the nearest gm dealership that coincidentally was at the closest exit off of the highway I was traveling on. The dealership performed diagnostic and determined that the damage was caused due to the ongoing gm recall associated with safety recall n252494000. My vehicle had previously been inspected as part of the recall and was found to have passed. Vehicle had been driven approximately 4,000 miles after recall was performed.

The engine has a knocking sound. I took it into the dealer and they replaced the exhaust system thinking that was the problem. However, the knocking still happens intermittently. I have video documentation of the noise.

Had a p1098 code. The truck was diagnosed by a certified technician. Found to have a failing coolant control valve. Gm has issued special coverage for this known failure. Special coverage is not including the VIN for this truck although it falls in the criteria for model, year, and engine model.

See attached document for complaint. Information, details, comments, dates, and numbers on recall 20211500 denali recall vehicle information: all models of gm's with 6. 2l gas engine (my personal truck I owned} • recall date: April 23, 2025 650,000 + gm vehicles with 6. 2l gas engine, years 2019-2023 • manufacturer recall number: n2524944000 (letter issued by state of washington dept. Of licensing, po box 9020 olympia, wa. 98507-9020 • NHTSA recall number: 25v274 • 2021 GMC 1500 sierra denali, x-tended cab, 4wh dr, 6. 2 l gas engine • VIN #: with 6,400 miles on my truck may 15, 2025 • went to local dealer, becker Buick-GMC in spokane, wa. , to verify there was a recall on my truck and VIN. #. Confirmed with there service department and sales person jon stone. • I was informed that the dealership, service dept. , and salesman jon stone, and sales mgr. Cameron could only say the following: "GMC does not have the tools made yet to verify if the engine will need to be replaced and would add me too the list and keep me posted. " • I was informed at this time that t he issues with the engine were: engine could stop and start again at random; the engine start to smoke and stop; the engine could catch fi re whether it was running or not, or the engine could do all three things. • I was told to just keep driving the truck but watch for any of these issues. May 28, 2025 • stopped in local dealer, becker Buick-GMC, again to see if any updates. • told GMC still had done nothing to develop the necessary tools to evaluate the engine and had no date to report or share with me on when they CO uld. • again, I was told to keep driving the truck and if I had a problem, becker Buick would come and tow me. • salespeople did ask if I wanted to just buy a new truck several times. They were impressed my truck only had 6400 miles on it and in such excellent shape. This was to be my retirement truck. June 5, 6, 7, 2025 • I visited several car dealers in the spokane, wa. Area. Ford, chevy, Dodge and Toyota. While looking at new/different vehic.

For the second time since I have owned the vehicle that was purchased brand new. The engine seized during driving on the highway and began making loud noises that was knocking and jerking the vehicle. The issue occurred initially around 15,000 miles and was diagnosed as lifter failure, was repaired and returned in July 2022. At 64,000 miles on January 15, 2026, while on an interstate the engine did the same thing and the vehicle went into limp mode. It has been diagnosed as lifter failure this second time and is awaiting appropriate repairs. Both incidents put myself in passengers at danger due to the nature in which the vehicle entered limp mode on the highway.

Driving down the road and engine shut off and would not start back. Had it towed to dealer and it needed a motor replacement. Waited over a month for the shop to finish it. New motor has 3k miles on it and is making noise, transmission is stuttering hard and the air conditioning quit working all around the same time. Had to take the truck back to the dealer after the replacement motor was installed because of a faulty “new” starter.

There is an active recall for the 6. 2 l engines, which is what I have and it’s an issue with burning oil and catastrophic engine failure due to rods and bearings. And I just got this vehicle in November and I have already went through 15 quarts of oil in two months so I’m waiting for my engine to blow up going down the road to cause a wreck like has happened to multiple vehicles already and I also have a rod knock now due to this issue so it could be any time now that my engine fails and I end up getting hurt or my family I took it to the chevy dealership and I have called gm to do an oil consumption test and to put in a claim so that way if it does fail, then it has paperwork to follow, but it is a major safety concern but something needs to be done considering there’s already 600,000 recalls on this issue already there needs to be more for the rest of the people that are having this issue like myself and I’m spending $50,000 on this truck for the engines to fail and me end up dying before something‘s done. And it’s also very distracting as you’re driving down the road and your vehicle tells you that you’re low on all so you have to try to find a way to get off the highway to have someone bring you all so you can continue to drive and it’s not just a cordial. It is up to 5 quarts of all at a time.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 50-65 mph on an incline, the contact believed that the transmission was slipping or there was a misfire coming from the engine. The contact stated that the vehicle failed to restart automatically after the engine auto start/stop system was engaged after a complete stop. Additionally, the contact stated that after driving for a while, the vehicle went into limp mode. The check engine warning light and other warning lights were illuminated. The vehicle was taken to the dealer to be diagnosed. The contact related the failure to gm campaign number: n252515590 (corroded ground strap); however, the dealer had informed the contact that the vehicle was not covered because the VIN was not included and there was no warranty coverage on the vehicle. The vehicle was not yet diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA hotline for assistance. The failure mileage was approximately 75,000.

Complete engine power loss.

Engine failure without any warning. Car maintenance was kept up-to-date.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the engine seized. The contact was unaware of a warning light being illuminated. The contact stated that while attempting to start the vehicle, the vehicle failed to start. The vehicle was towed to the dealer, where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact referenced an unknown engine recall; however, the VIN was not under recall. The manufacturer was made aware of the failure, and a case was filed. The contact was advised to report the failure to the NHTSA hotline. In addition, the contact was informed that the VIN for the vehicle was a canadian VIN, and the mileage was displayed in kilometers. The failure mileage was approximately 120,000.

Had a "trans hot warning" light. Dealership said it was internal valve body failure. They said there is recall on this for other engine types even though this is same issue. I think GMC needs to expand their recall.

The engine is knocking and running rough. I took it to christian brothers automotive in newnan GA and the advised engine replacement.

The contact owns a 2021 GMC Sierra 1500. The contact received the recall letter for NHTSA campaign number: 25v274000 (engine and engine cooling). The contact called the local dealer, who confirmed there was no information from the manufacturer to move forward. The vehicle was not diagnosed or repaired. The manufacturer was not contacted. The contact had not experienced a failure.

The contact's grandson owns a 2021 GMC Sierra 1500. The contact stated that after the vehicle was purchased from a private seller and driven 258 miles, while his grandson was merging off the exit ramp, the engine seized. The low oil pressure warning light was illuminated. The contact stated that the check engine warning light was illuminated prior to the failure. The vehicle was towed to the contact's residence. The contact scanned the vehicle and retrieved dtcs: p0011, p0016, p006dd, and p0521, stored dtcs: p06dd p0011, and permanent dtcs: p0011 and p0016. The engine was replaced by the contact. The local dealer was contacted for parts. No further information was available. The manufacturer was not contacted. The failure mileage was approximately 100,148.

I just surpassed my extended warranty (5 year/100,000 miles) by a couple of thousand miles and my coolant control valve has gone out. The problem is so common that the part is on back order for months at a time. Gm says that they issued special coverage for 2020-2022 models, but my dealer is telling me that my VIN is not covered. They want to charge me $2,400 to replace it. This is insane. It’s a very common problem that they know about and it’s going to almost break me. We need help!.

Took the vehicle to the dealer because of an engine noise. It had issues with the valves knocking when it had around 1000 miles. I took it in and now the truck has around 67,000 miles and I’m being told it needs a new engine because of a bent rod in the engine. I was told that I need a new engine. Previously I had a lot of other issues with the front wheel hubs clicking. But, this truck didn’t even make it to 5 years and now it needs an engine.

My wife was driving at highway speeds with all are kids when the trucks motor suddenly loss all power all check engine lights illuminated and what I'm assuming had major engine failure causing rod knock.

Heard a ticking noise then check engine light started blinking along with service esc and parking brake. Took it to the dealer and I had a bad lifter again. I was previously repair for lifters under warranty a little over 2 years ago.

Following the remedy of the engine recall in 2025, the truck started having intermittent electrical issues (I. E. Warning lights on dash turn on/off: service 4wd, loss traction control, etc) come one while the truck is being driven. If the truck is turned off while the dash warning lights are on, it will not start for about 24 hours. If the warning lights are ignored, eventually they will go off on their own. Additionally, the truck is having "no-start" problems (randomly the truck does not start, then after a few days it starts). A new development, when backing up there is a scraping/squealing sound (possibly universal joint). Truck has been back to the dealership that replaced the engine block for the recall and they have failed to identify any issues as these problems are intermittent. Engine recall replacement invoice (attached).

On 10/21/2025 as I was traveling on the highway in kansas at 60 mph, the vehicle lost power and the engine went into limp mode immediately reducing the speed dramatically. Multiple warning lights flashed on the screen. I was able to get the truck to the side of the highway. The vehicle never started again. I was informed by the dealer that the vehicle would need a new engine.

I own this 21 GMC sierra with a 6. 2l. This VIN is not part of your current recall. But my truck is at a dealership waiting on a replacement engine. I was told that the engine locked up in the bay. Not sure if any lights came on before the engine failed, the dealer did not go into that much of detail. The truck is sitting outside waiting on the engine, not sure if gm made then do any failure analysis or just said its a 6. 2 were sending an engine.

I just took my 2021 GMC sierra 1503. 0 duramax diesel into faulkner Nissan, today 10/18/2025 m, to have that recall fixed. I picked it up from the dealership and drove about 10 miles before it went into limp mode and reduced power mode while I was driving and started to shift very roughly and I’ve never had any issue like this before they supposedly fix this recall, I think the software patch made it worse in my case. Now my vehicle is throwing a bunch of different transmission error codes, that it has never produced , and it is going into reduced power mode,as I’m driving and going into limp mode as I’m driving, which you never has done before and it feels like it’s stuttering in early gears now and the idle was really rough it didn’t idle at a specific spot it went from 800 to 1300 back down to 800 when it should’ve just been idle at 800. I don’t know what to do. It seems like this recall made the problem worse for me and my truck in this case, I don’t know what to do and I don’t know where to go. I hope you guys can help us. Please make GMC take responsibility before somebody gets killed. If they haven’t already this issue is extremely dangerous and I’m sure is destroying the transmission. I don’t feel comfortable driving my family in my vehicle anymore because of this issue it is terrifying….

I was traveling home from work and lost all power to the vehicle while driving. No warning lights, check engine lights came on. I was able to cross traffic and park it in a business place. I had it towed to a chevy dealership for diagnostic. They said that the timing chain came off and I would need a new engine. I had it towed to a auto mechanic shop for a second opinion and they gave the same result. The vehicle is only 4 years old with 92,000 miles on it. When I lost all power to the vehicle, I did not hear any strange noises.

Vehicle showing signs of a failing coolant flow control valve and/orcoolant temperature sensor. - ac takes a long time to cool down - engine fan will stay on after the vehicle is shut off - I often see the notice of “a/c off due to high engine temp” from what I can find, this issue I’m experiencing is a known point of failure in this vehicle make/model/year. On 10/10/2025, I took the vehicle to fountain Buick GMC service in orlando, FL. The service manager recognized the symptoms immediately, and even knew right away that the part to fix it was on back order - further bolstering that it is an issue that gm is aware of and deals with regularly. Per the service manager, gm’s initial response was to issue a “pay to play” software update that is covered under the 3yr/36,000 warranty, but not the 5yr/100k. Out of warranty, this “solution” costs $499. 99, and has a < 10% degree of success. If the update doesn’t fix the issue, then it would be covered. However, the need for the software update was not communicated to consumers. Regardless, since the issue is not yet severe enough to be recognized via code (despite symptoms, pictures, and video), gm will not take any action under warranty towards fixing it at this time. The vehicle’s 5yr/100k warranty expires on 10/15/2025. If the code throws on 10/16/2025, it will not be covered under warranty, but * be covered under dealer assistance. And regardless, the $499. 99 charge will apply, independent of warranty coverage. More important than the money is the safety. The engine’s temperature is not being regulated, the symptoms I’m experiencing are terminal, and this issue will not be fixed on its own.

Dtc code p1098 present related to faulty coolant control valve on 3. 0 duramax diesel engiine. This is a known issue with this engine and is supposed to be covered under the 100k mile powertrain warranty. Previously took vehicle into dealership for repair involving replacement of the coolant control valve but was told reprogramming of the ecm was required first step per gm repair bulletin. Reprogramming cost me $195 and was told this was not covered under the 100k powertrain warranty. Now, a few months later, the same issue and dtc code p1098 happened again while driving on freeway at freeway speeds and caused vehicle computer to limit speed of the vehicle which caused hazardous situation in construction zone as was not able to maintain speed of traffic while towing trailer with boat. I also understand that gm has issued special extended warranty related to this coolant control valve in September 2025 which extends the warranty coverage up to 15 years and/or up to 150k miles but I was told at the dealership that my VIN# does not qualify for this extended coverage for some unknown reason?.

While traveling to work at 75mph, a sudden an unexpected malfunction of internal engine components caused a loss of propulsion.

The contact owns a 2021 GMC Sierra 1500. The contact had received notification of NHTSA campaign number: 25v274000 (engine and engine cooling). The vehicle was taken to the dealer where an inspection was performed on the engine. The contact was informed that the vehicle had passed the inspection, and the mechanic added a higher viscosity oil, installed an oil fill cap, replaced the oil filter, and updated the owner's manual. The contact stated that the remedy failed to address or repair the possible defect with the engine. The contact stated that the remedy resulted in a higher cost for oil changes, and fuel economy had decreased from 21 miles per gallon to 18 miles per gallon. The manufacturer was made aware of the issue and the contact was provided a case number. The contact stated that the vehicle had not been repaired. The failure mileage was unknown.

On [xxx], at approximately 15,873 miles and while on the freeway approximately 30 miles from my home, my GMC Sierra 1500 with the l84 engine experienced a failure of the dfm lifter assembly. This required a significant engine disassembly and the replacement of multiple valvetrain components. This repair was performed at gold rush Chevrolet in auburn, CA, as documented in the enclosed service invoice. Gm has issued technical service bulletins and product communications addressing similar lifter failures in gen v small-block v8 engines with dfm/afm, including service update n212353840, pip5776, #19-na-219, and related updates. Industry coverage and owner reports and current class action lawsuits indicate that these failures can recur, even after initial repairs, due to the high cycling frequency of the dfm lifters. Given the nature of the defect and gm’s documented acknowledgement of the issue, I am requesting that gm extend the powertrain warranty coverage for the engine and related valvetrain components for a period of 10 years,100,000 miles as a goodwill policy adjustment. A warranty extension would ensure customer confidence and protect against the significant cost of a repeat failure. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

After having transmission issues which was replaced under warranty, within 300 miles, the engine failed. The vehicle has now been sitting at the dealership since October 7, 2025 waiting for a replacement engine. There is no timeline available for the replacement engine as they are currently backordered. Absolutely ridiculous.

I have a 2021 GMC Sierra 1500 at4 3. 0l diesel pickup truck with 98,500 miles. The coolant control valve failed on my vehicle and for some reason it is not covered under gm's special bulletin that covers this part 15yr/150,000. Ridiculous.

I purchased a 2021 GMC Sierra 1500 denali (VIN: 3gtu9fel5mg467929) from j. C. Lewis Ford in pooler, georgia. The dealership did not disclose an active federal safety recall (NHTSA campaign number: 24v-xxx / gm n252494000) related to engine connecting rod and crankshaft defects that can result in sudden engine failure and loss of propulsion. The blue certified delivery document they had me sign includes a section requiring disclosure of any open recalls, but they left the recall section blank and checked that all recalls were explained to me. No disclosure of any recall occurred during the sale. The vehicle developed engine problems within days and is currently in GMC service. The nondisclosure put me at risk of driving a vehicle with a known safety defect. I am reporting this as a dealer nondisclosure of a federal safety recall.