general problems of the 2023 GMC Sierra 1500 - part 1

I am reporting a serious safety concern involving a 2023 GMC Sierra 1500 denali, 6. 2l l87 v8, VIN [xxx]. This vehicle has now experienced two catastrophic powertrain failures at very low mileage. The first catastrophic engine failure occurred at approximately 23,696 miles. The vehicle was taken to a GMC dealer, where the repair documentation states that the engine had suffered significant internal damage, including damage to the #3 connecting rod, a missing connecting-rod bearing, bearing material throughout the engine, and a scored crankshaft. The dealer determined that the engine was seized and required replacement. Gm replaced the engine under warranty with gm engine assembly part number 12740076. The vehicle has now experienced a second catastrophic failure. On [xxx], while traveling approximately 40 mph, experienced grinding, lurching, and knocking, followed by a complete loss of propulsion. The truck would no longer move and had to be towed to a GMC dealer. At the time of the incident, no warning lights or warning messages were observed. The transmission is also suspected to have failed, although the exact cause and extent of the transmission failure have not yet been determined by the dealer. I understand that NHTSA is currently investigating failures involving gm 6. 2l l87 engines, including failures occurring after previous recall remedies and engine replacements. I am therefore requesting that this incident be included in NHTSA’s investigation and considered when evaluating the effectiveness of the existing recall remedy and the safety of replacement l87 engines. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

My wife and I were driving on the highway going slightly uphill. I pushed the pedal a bit because the power wasn't keeping speed. It continues to not maintain so pushed throttle further and the truck stalled. We traversed 3 lanes to get to the shoulder. When I stoped I tried to restart but the car wouldn't turn over but all electrical were working. We were on the shoulder for over and hour on a main highway. We had aaa tow it to the dealership where they confirmed the engine was seized and will be ordering parts. The car is still available upon request. Our safety was at risk from loosing power on the interstate and sitting on the shoulder is very dangerous. I didn't receive any warning lights prior to this occuring. The truck did undergo the peko test and passed and added new oil viscosity. It had roughly 55k miles on it. Always changed the oil before it hit 0% oil life as told by dealerships.

Sudden loss of propulsion while driving on I-75 with cruise control engaged. Vehicle began to decelerate. Pulled off onto emergency lane. Engine was idle-ing roughly. Would not increase rev when gas pedal pressed. Shut down. Tried one restart. Unsuccessful.

Driving on I-75 with cruise control engages. Vehicle began decelerating. Pulled over onto emergency lane. Engine idled roughly. Shut down. Attempted one restart unsuccessfully.

The engine made a noise and it seems to me that this engine will loose power and leave me in a situation that could cause an accident or breakdown in the middle of a bad situation. I don't trust this truck and its engine and I refuse to drive it now.

During a family camping trip, our engine seized without warning — a failure directly tied to an active GMC recall. Despite this being a manufacturer defect, GMC roadside assistance refused to provide full support and informed us that we were responsible for towing our trailer home. This placed an unreasonable financial and logistical burden on us during an already distressing situation. To make situation worse when we brought the vehicle to o’meara GMC for the recall repair four months prior. They kept our truck for an entire week, only to inform us that their “solution” was to put heavier-weight oil in the engine. This is not a recall repair. It is not a fix. It is a temporary workaround that demonstrates clear incompetence and an inability or unwillingness to replace the motor as required under the recall. O’meara GMC failed to perform the recall repair, failed to replace the engine, and failed to provide any meaningful resolution. Their actions have left us with a vehicle that is unsafe, unreliable, and not repaired according to GMC’s own recall standards.

The 6. 2 engine in my truck failed while driving and it has been determine that I need a new motor. This motor was on the recall list. I brought it in for the pico recall test in October we 2025 and it passed. They then changed the oil for a much more expensive 0w40. The engine failed in August leaving me stranded on side of the highway. It has been at the dealership since August 7th. There is no eta on when the new motor and parts will be available because I’m being told that some parts are on back order. I have looked into trading it in and the value of this truck due to the 6. 2 engine recall is significantly lower that it should be. It’s half of what I paid for it 3 years ago. I incurred towing fees and uber fees. I am no without a truck to tow with.

13 unresolved problem codes relating to hard engine starting,rough engine running,vehicle initiating safe mode operation, upon a highway trip. P0016 engine code detected and onstar messaged for immediate service. No resolution at dealership , after resetting codes an additional 9 are active / pending at 2nd dealership visit. Abnormal engine operation since , dealership advises a hard failure has to occur before a resolution can be instituted. Similar advice from GMC direct phone call in help line.

I, [xxx], am currently getting my engine replaced for the 1st time because of an engine failure. Engine completely shut down in the mountains while I had my 3 young kids ([xxx], [xxx] & [xxx] old) on our way to our vacation. 102 degrees outside no ac, no water for 4 hours until a tow truck finally came. The kids were scared for their life due to being on the side on the road, hungry with nothing to do but wait. Literally had just enough clearance to get on the side of road where vehicles drive-55-65 mph. Avenal, CA to be exact. What’s the best way to get my money back? I do not want to continue to deal with these problems on the road with my little ones. The dealership is currently looking to replace my engine and waiting on parts. There has not been an official date I will get my vehicle back. Thank you in advance. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Driving down the interstate at 70 miles per hour, started losing power, engine light came on. Engine started making a loud banging noise as I pulled onto an exit.

I own a 2023 GMC Sierra 1500 denali ultimate equipped with the 6. 2l l87 v8 engine. The vehicle previously experienced an engine failure that resulted in the complete replacement of the 6. 2l engine by an authorized GMC dealership. The replacement engine was installed at approximately 76,316 miles. After approximately 1,000 miles of driving with the replacement engine, at approximately 77,354 miles, the vehicle displayed a check-engine/service warning and experienced abnormal transmission shifting. I returned the vehicle to the GMC dealership for diagnosis. The dealer documented dtc p0747, identified as “transmission control solenoid valve 1 stuck on,” and recommended replacement of the transmission control valve body at a quoted cost of $2,665. 85 plus tax. The dealership has stated that this transmission condition is unrelated to the recent engine replacement. However, because the condition appeared only approximately 1,000 miles after a complete engine replacement, I have asked general motors to investigate whether the current failure could be associated with the previous engine failure, the engine replacement procedure, or other related vehicle systems. I have opened a case with general motors customer assistance and have deferred the customer-paid valve-body repair while gm reviews the matter. I am submitting this complaint so NHTSA/odi has a record that this vehicle experienced a major 6. 2l l87 engine failure requiring complete engine replacement and then, approximately 1,000 miles after that replacement, developed a check-engine warning, abnormal transmission operation, dtc p0747, and a condition requiring replacement of the transmission control valve body. I can provide the engine-replacement repair order, current diagnostic documentation, mileage records, dealer repair estimate, and gm case information upon request.

While driving, my 2023 GMC sierra with the l87 6. 2l engine experienced a sudden, complete, catastrophic loss of engine power. There were no warning lights or messages prior to the failure. This was a one-time event, but it left the truck inoperable and I have been without the vehicle since it happened. The vehicle had recently passed applicable recall checks and had a routine oil change performed, so it was properly maintained leading up to the failure. A sudden loss of engine power while driving poses a serious safety risk, including the possibility of a collision if it happens in traffic or at highway speed. It is unknown whether a dealer has confirmed the root cause, as the vehicle has been out of service since the incident.

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving approximately 40 mph, the check engine warning light illuminated, and an oil message was displayed. The vehicle stalled and was unable to be restarted. The vehicle was towed to a dealer where it was diagnosed and determined that the engine needed to be replaced. The vehicle was repaired, but the failure reoccurred approximately two weeks later. The vehicle was taken to a different dealer but was not yet diagnosed. The manufacturer was notified of the failure. The failure mileage was 29,000.

Complete engine failure while driving on a highway. While cruise was set, the truck emitted a sound and sensation like we had run over something on the highway. Within a few minutes the engine started ticking. The cruise was disengaged which thru the truck into neutral. No dashboard sensors were illuminated. We were able to get off the highway but the truck would not restart. Truck was towed to nearest dealer who has confirmed engine failure.

Complete engine failure. Safety is was put at risk one engine lost propulsion on a bridge with no median. Truck towed to a gm dealer that inspected it and replace the engine. Check engine light and low oil pressure light came on approximately 30 seconds before the engine died.

Engine knocking. Engine being replaced under warranty due to premature bearing failure. Picotest was performed prior to my purchase with 12800 miles. 0w40 oil being used at the time of failure. At the dealer now getting the engine replaced.

While traveling at highway speed during rush hour commute, the vehicle lost engine power and stalled. While coasting, I tried to restart the engine several times without success. Before coming to a stop, I attempted to get to the shoulder safely. Unfortunately, a portion of the vehicle was left partially in the lane and on the shoulder. Once I was completely stopped, I tried to put the electronic shift control into neutral so I could push the vehicle safely to the shoulder. The shifter would not allow me to shift into neutral and other override methods researched failed to work. I continued to try and restart the vehicle without success. I was in an unsafe position during rush hour commute for about 50 minutes until roadside assistance arrived and loaded and towed the vehicle. There was no warning of the issue prior to the incident. A code (p129f-fuel pump driver control module speed signal incorrect) was produced after the stall occurred via my GMC app. My vehicle was towed to my local dealership for service, but have not received the vehicle back at the time of reporting.

1. The l87 engine loss of propulsion failed and is available for inspection at the service department at power swain Chevrolet dealership, fayetteville, nc. 2. I, other vehicles, cyclists, and pedestrians were at risk. That vehicle could have come down on the highway, causing a vehicle pileup, which could have caused mass casualties. 3. The problem is known; the service advisor informed me the vehicle's engine needed to be replaced. 4. There were absolutely zero warning lamps or my GMC app alerts to announce vehicle issues. I have attached the last two maintenance records I have on hand. I suspect the dealership will try to deny responsibility for repairs. An extended warranty most nearly means we expect it to break down and your safety is not our concern.

Oct 2025 I took my truck into my local GMC dealer for 6. 2 recall. I was told it passed the testing. 6/12/26 driving about 70mph on highway and lost all acceleration. Warning stating engine oil hot,/ pull over and idle engine. Already using 0w40 oil for approx 8momnths. Oil changed approx 3 wks before this incident. I was able to pull to the shoulder w/in 1/4 mile. While the truck was still moving about 3 mph it went into park and shut off. The vehicle would not turn back on. Oil level was full. For about $300 I was able to have the truck towed to a local dealer (about 2hrs from my home) and have my trailer towed off the highway. 6/15/26 I was notified by a local dealer that the engine was seized and that this was probably the recall issue. I contacted my local dealer who had my truck towed to their location. On 6/19/26 I was told by local dealer rep that they had ordered an engine for my truck and that I was third in line. On 6/26/26 I was informed by the dealer that he engine is on an indefinite backorder nationwide. On 6/30/26 I received a call from gm giving me a case number and getting contact info for my local dealer. I was advised that someone would contact me within 48 business hours. 7/3/26 I was contacted by my case advisor from gm. Still no idea when replacement engines might be available. I inquired about a buyback since I need a truck for work/personal life. I advised her that I had already cancelled one vacation (towing an RV. . . My loaner Buick encore won't work) and would probably have to cancel another. I tried to explain that farming doesn't work well with the loaner either. I was told that another advisor would look into a buyback situation. On 7/8/26 I received a call from gm advising that my engine had shipped on 7/6/26 and to expect a call the following week with an update on completion.

The contact owns a 2023 GMC Sierra 1500. The contact stated that while operating the vehicle, there was an engine knock at start-up, and the engine intermittently hesitated and skipped. The vehicle was taken to the local dealer, who performed a pico test on the engine, and the engine passed. Later, while hauling a trailer, there was a rattling sound coming from the engine. The vehicle was taken back to the dealer, who diagnosed the vehicle and determined that the engine needed to be replaced. The engine, radiator, and oil cooler were replaced, and the vehicle was repaired. The manufacturer was notified of the failure. The failure mileage was 17,000.

Model: sierra denali ultimate engine: 6. 2l v8 VIN: [xxx] mileage at most recent incident: approximately 52,000 miles safety complaint summary I am submitting this complaint to report a recurring loss-of-propulsion and engine power event involving my 2023 GMC sierra denali ultimate equipped with the 6. 2l v8 engine. This vehicle has experienced two separate incidents in which it suddenly lost power while being operated at highway speeds. During both events, the vehicle unexpectedly lost propulsion without warning and without any apparent driver input or mechanical indication beforehand. No warning lights, check-engine lights, reduced-engine-power messages, service transmission messages, or other warning indicators were displayed prior to the failure. The vehicle simply lost power while traveling in traffic. During both occurrences, I was forced to safely maneuver the vehicle to the shoulder of the roadway while rapidly losing speed among surrounding traffic. Once stopped, the vehicle would not resume normal operation until it was restarted. After restarting, the vehicle appeared to operate normally; however, the fact that this condition has now occurred twice raises significant concerns regarding the reliability and safety of the vehicle. Safety risk this condition presents a significant and immediate safety risk because sudden loss of propulsion during highway operation can leave the driver unable to maintain speed, safely merge, maneuver, or avoid surrounding traffic. The unexpected reduction in speed creates the potential for rear-end collisions, loss of vehicle control, or other traffic accidents, particularly when operating on high-speed roadways. Because the vehicle provided no warning before losing power, there is little opportunity for a driver to take preventive action. Additional information • vehicle: 2023 GMC sierra denali ultimate • engine: 6. 2l v8 • VIN: [xxx] • approximate mileage: 52,000 miles • number of incident information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 55.

The lifters on my 2023 GMC sierra failed and damaged my engine. The truck has approx 78,000 miles. I do have an extended warranty to 100,000 miles. I got the truck to my GMC dealer who confirmed the problem was lifter failure. There might be camshaft damage but will have to tear the engine down. It seems like GMC is dragging there feet. It is known the lifters are a problem on this engine but GMC continues to sell them. There was no warning that the lifters would fail. The lifters could have failed while driving at high speeds and the driver could loss control.

I was driving my family on the highway and my truck completely shut down. The screen flashed a warning and it slowly started decelerating. Thankfully I was able to make it to the shoulder of the road safely. Engine failure was a known safety issue with my model of truck, but I completed the l87 engine loss of propulsion safety recall testing on 9/18/2025 and was assured my engine passed the testing and was not at risk for engine failure.

Truck starting bottom end knocking noise at 57,700 miles. Engine had the recall done to it for pico test and passed. Dealership states now it will need a new engine.

This vehicle has experienced repeated catastrophic engine and drivability failures since purchase and has now undergone four engine replacements under warranty. Despite these major repairs, the vehicle continues to experience dangerous shutdown/stalling conditions. The primary safety issue occurs while braking or coming to a stop. The engine will suddenly shut off unexpectedly, creating a serious traffic hazard and leaving the vehicle unable or difficult to restart. This has occurred multiple times and creates a dangerous situation in traffic and at intersections. The vehicle remains under manufacturer warranty, however the defect has not been successfully repaired despite extensive service attempts and multiple complete engine replacements. The condition substantially impairs the safety, reliability, and use of the vehicle. This vehicle was acquired through a fleet/lease arrangement for company use and was not purchased for resale. It is a light-duty 1500-series pickup with approximately 7,100–7,200 gvwr used as a company vehicle. Complete repair history, diagnostic records, warranty repairs, and engine replacement documentation can be obtained from: stevens GMC bristol, connecticut the vehicle has been repeatedly presented for repair and the defect remains unresolved. This appears to be a serious ongoing safety-related defect involving engine shutdown/stalling while braking or stopping.

[xxx] [xxx] phone: [xxx] vehicle information: year: 2023 make: GMC model: sierra denali ultimate engine: 6. 2l v8 VIN: [xxx]: mileage: approximately 52,000 miles background: I previously had the engine serviced under a gm recall campaign related to known 6. 2l v8 engine concerns. Despite that repair, the vehicle has since experienced two separate highway-speed loss-of-propulsion events. Complaint the vehicle suddenly lost power while being driven at highway speed. No warning lights, check-engine lights, reduced-engine-power messages, or transmission warnings appeared. In both incidents, I was forced to coast to the shoulder of the roadway. The vehicle would not resume normal operation until it was stopped and restarted. This condition has now occurred twice. Safety concern the sudden loss of propulsion during highway operation creates an immediate safety hazard and increases the risk of collision due to the inability to maintain speed with surrounding traffic. Requested NHTSA action 1. Record this complaint as a repeat loss-of-propulsion event. 2. Evaluate whether similar complaints exist involving 2023 GMC sierra denali ultimate vehicles equipped with the 6. 2l v8. 3. Consider this complaint in any current or future investigations involving loss of propulsion, stalling, engine failure, or powertrain concerns. 4. Review whether vehicles previously repaired under gm recall campaigns continue to experience similar failures. [xxx]: update – vehicle disabled and awaiting engine replacement since filing my initial concerns regarding repeated loss-of-propulsion events, the condition of my vehicle has significantly worsened. During the dealership's inspection and test drive, the engine reportedly failed and locked up. The vehicle could not be restarted and required further diagnostics. On June 20, 2026, I received a text message from the dealership that the required engine parts remain on backorder information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

After driving my vehicle for a short period of time I stopped to go shopping. When I returned to my vehicle I started it as usual and the check engine light illuminated. I began driving and within 0. 25 miles I received an info enter message that stated my vehicle would have reduced acceleration and to please drive safely. My engine fans became noticeably louder and ran the entire trip home (about 15 minutes). After pulling into my driveway I sat in the vehicle and listen to the fans continue to operate. Additionally, my onstar system, wifi, and navigation systems quit working. A p1098 code was returned when using a diagnostic code device. Disconnecting the battery would cause the check engine light to extinguish and for the truck to operate without reduced acceleration; however, onstar, navigation and wifi would not work. After shutting off the engine and then restarting the check engine light would once again illuminate and the reduced acceleration message reappeared.

On may 13. 2026 traveling southbound on i15 utah at 75 mph the engine stop and put the tranmisson in n and I move the truck to a stop. Then the truck shut down. I had the truck tow to the nearest GMC and was informed that the engine had sezed. I had recalled done to pervent engine failure.

Catastrophic internal engine failure on my 6. 2l engine. Several times vehicle was to gm gunn Buick GMC regarding power loss knocking noises. Received the run around that vehicle past all their initial inspection and test. They only replaced a valve lifter replacements bank 2 without further assessment of the engine or components. I took my vehicle to another shop to conduct a thorough inspection and they found broken metal from the piston/skirt and likely connecting rod damage inside the crankcase. Broken piston skirt/piston material • cylinder wall damage/scoring • metal debris throughout lower end • possible bent/broken connecting rod • potential crankshaft/journal damage from debris circulation • oil pickup area contaminated with metal lifter failure leading to dropped valve/ piston contact • rod bearing failure • oil starvation • spun bearing • piston failure/detonation advised gm gunn Buick and GMC of the secondary engine inspection by another shop. Manager told me it was my issue now and they wouldn’t replace my engine it wasn’t there problem. I had to pay out of pocket for a new engine replacement due to the negligence of gm and their agency lack of maintenance and customer care and service.

Traveling had an engine light come on. Stopped at a dealer they inspected found multiple errors reset engine light and said continue home. When home bring into my dealer. Got home that night went to start truck, all kinds of errors started popping up on the dash, vehicle would not turn over at all. Had to call wrecker to have brought into shop. First issue could not put the truck into neutral at all, so they had to pull in park to put unto the bed of wrecker (that seems to be a very poor design of the truck). Brought truck into shop received a call two days later that it is fixed and working fine. Went to the shop asked what the problem was, told there is a ground strap under the truck that is like the main part to make sure everything works regarding electronics. The dealer has had to repair many of these ground straps, they are exposed to the elements and come loose I was told. They had two other GMC trucks in the shop with the same issue that day. The ground strap is exposed to the elements do not understand why this would not be covered just like a battery lead to stop from corroding and have to clean it or replace it. Not to mention there is no where in the service manual I can find about any maintenance that needs to be done with it. Appears to be a very bad design from the car manufacture.

After completion of recall repair, changing oil weight from 0w20 to 0w40, I encountered loud squealing and knocking sounds from the engine bay. As catastrophic failure has been reported the vehicle was immediately taken to the closest gm dealership, southern Chevrolet of chesapeake, va.

I took the truck in for a recall they notified me and said it failed the test and there was metal in the oil and said it needed a new engine.

Start engine light came on while driving. The truck did a dead stop in the middle of the road. Tried to restart but nothing. A tow truck was called and the truck was dropped off at the local GMC dealer. The next day the dealer called me and told me I need a new engine. 39,000 miles.

I brought this truck brand new. Had issues the first couple days of purchase that was a quick fix, but as time went on things got worse. Truck always stalling out, engine has been replaced once already due to a recall and months after the first replacement, it stalled out on me again in the middle of the freeway and I just got a call from the dealership that it needs another new engine! how is this right! how is this safe! I could've lost my life on every occasion it has happened.

On April 1, 2026 at approximately 7pm the vehicle had a complete engine failure exiting an interstate. As I was slowing to exit the interstate the truck, without warning, lost power and locked up the rear wheels. I was able to safely exit onto the off ramp, but did partially block the off ramp for 45 minutes waiting on a tow truck. Once I came to a complete stop the dashboard began displaying numerous error codes, included "key missing, restart truck and shift to park, and start failure". The vehicle was part of the gm l87 engine recall but had previously passed the pico test and was deemed ok to drive. I had the vehicle towed to the closest GMC dealership where it was diagnosed as an engine failure and the engine was locked up. The vehicle has been at the GMC dealership since the night of April 1, 2026 with no date given as to when it will be fixed. The vehicle had displayed no signs of any problems prior to the engine failure on April 1, 2026.