general problems of the 2023 GMC Sierra 1500 - part 1

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.

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.

Engine sudden loss of power. Wheels locked up and I skidded off the road.

Based on the critical recall and safety concerns for this known issue for the 6. 2 l87 engine failure I am highly concerned that it takes over 171 days to just get an appointment to look at this issue. This is further compounded by the fact I put approx 800-1000 miles a week on my truck and now am worried about having an accident or blowing my truck up.

Motor locked up on highway with heavy traffic trying to exit highway.

Our truck had just passed 60,000 miles when the engine seized. The recall procedure was completed in January, and the engine passed the test at that time. We were also using the recommended 0w?40 oil. Despite following all guidelines, the engine still failed. This shows that the procedure gm has outlined is not sufficient to determine whether an engine is actually in good condition.

My 2023 GMC sierra has 60,571 miles for a while now while driving the transmission slips and slams into gears. Recently driving with my kids in the car on highway going 70mph the back brakes locked up multiple times, so scary and dangerous while driving. I now currently have a code p-0747 in the system.

While driving home from phoenix on hwy 95, 30 miles out of tonopah on the way to reno engine propulsion and the complete engine failure occurred while driving at 75 mph. No warning at all. No cell service, had to use onstar to be our savior. Thank god they sent a tow truck, although my wife and I with 2 dogs had to wait 4 hours for the tow truck, while semi’s rolled by us going 80 mph. Dealer performed diagnostics on my truck and has to replace the engine due to engine failure. I had the recall completed in September with the new approved oil and cap. I know this is an ongoing problem with gm’s 6. 2 engine. Complete engine failure while driving at 75 mph. No engine warning sign. Screen went blank. I will no longer trust this truck or have any confidence in the truck once I get it back. I sure hope gm pays for this. This has caused me endless anxiety.

My vehicle is a GMC Sierra 1500 duramax diesel. The vehicle experienced a failure of the def (diesel exhaust fluid) system, which was diagnosed by the dealership as a failure of the def tank heater. The heater is integrated into the tank assembly, requiring full replacement of the def tank. As a result of this failure, the vehicle became unusable and has been out of service since March 3, 2026. The dealership confirmed that the required part is on national backorder with no confirmed availability date. This condition creates a significant reliability and potential safety concern. When the def system fails, the vehicle can enter a reduced power or speed-limited mode, which may occur during normal driving and could create unsafe conditions in traffic. Additionally, there appears to be a broader pattern of similar failures affecting other vehicles of the same type, combined with extended delays in obtaining replacement parts. The lack of parts availability results in extended periods where the vehicle cannot be safely or reliably operated.

Driving along a main road at 40-45 mph and coasting toward a traffic light, the engine stalled out. Traffic light turned green and the vehicle would not accelerate. There were no warnings, check engine lights, or sounds. I could not pull to the shoulder due to traffic and had to pull into a left hand turn lane. The truck would not restart. Electrical systems seemed fine. Engine would turn over but not start on multiple attempts. One attempt finally got it to start but it immediately stalled. I was stuck in a dangerous situation at a busy intersection and no way to move the vehicle. It has been towed to the dealership.

Engine with leas than 40,000 miles is consuming one (1) quat of oil every 2,000 miles. Gm dealership showed me the internal gm service update stating the accepted rate of oil consumption for engines uses in the vehicles referenced is 1qt per 2,000 miles. That may seem acceptable because gm put it in a notice to dealerships but I assure you the end consumer would never buy this engine if this was explained prior to purchasing. There is a reason new cars to not consume oil (at least not at a level you need to add oil between oil change intervals) at this rate. Long term wear and tear on the engine - note gm offered a warrantee covering 100,000 miles, which is nice but the problems will become more severe over time and miles. I consider this borderline criminal as it will surely cause engines to lock up.

Vehicle exhibited a sudden loss of power, dash screen stated a restart of the vehicle was needed. I was able to coast into a neighborhood upon attempting to restart the vehicle nothing would happen and it would not even attempt to turn over, proceeded to contact onstar for roadside assistance, vehicle taken to nearest GMC dealership where it was determined to have engine failure and a new engine under warranty will be installed.

Motor seized while driving.

On Saturday at approximately 5:30 p. M. , while driving on a two-lane city street with vehicles around me, my GMC sierra began malfunctioning. The gauges flickered, warning lights appeared, and a transmission warning activated. As I attempted to safely pull over, the vehicle began stuttering and then completely stalled in the middle of traffic. Cars swerved and honked to avoid hitting me. Fortunately, no collision occurred, but the situation was extremely dangerous and frightening. Aaa towed the vehicle to the GMC dealership. When I informed them of the incident, I received a text asking whether an over-the-air update had been performed prior to the stall. I confirmed the vehicle had received an update within the past three months. I was then told there is a bulletin stating that after an over-the-air update, the vehicle may suddenly lose communication with multiple modules and stall. The foreman indicated this was likely the cause and that they were consulting technical assistance. I asked when it is considered safe to drive a GMC vehicle following an update, as I was never warned that the vehicle could suddenly lose power and stall without notice. I was told they were investigating further. Yesterday, I was informed that engineering directed them to replace the ecm (engine control module) and the fuel pump control module, with the ecm expected to arrive next Wednesday. I have not been given a confirmed timeline for completion. This appears to be a serious and known issue within GMC, yet there has been no recall and no warning provided to consumers. I was unknowingly driving a vehicle susceptible to sudden and complete power loss. This failure placed my life, my family, and the safety of others at significant risk.

Engine lost all power while I was attempting to make a left turn at a very busy intersection. Dash kept saying “check battery”, jump pack did nothing. Engine wouldn’t start.

Incident summary: on 2/2/2026, my vehicle was serviced under safety recall 25v-274 at an authorized GMC dealership. The service technician performed the mandated diagnostic protocol (including the picoscope test) and informed me that the engine had "passed" inspection. No internal components were replaced; the remedy was limited to an oil change to a higher-viscosity oil (0w-40) and a new oil filler cap. The failure: approximately 48 hours after this "successful" recall remedy, the vehicle suffered a catastrophic engine failure while in operation. The engine failed entirely. The vehicle lost all propulsion while in motion, creating an immediate safety hazard for myself and other motorists. Diagnostic and risk: the failure has been confirmed by a GMC dealer, who subsequently performed a full engine and radiator replacement. In the 48-hour prior to failure, there were no warning lamps or symptoms; the vehicle had just been cleared by the manufacturer's own diagnostic tools as safe and free of defects. Systemic concern: this incident demonstrates that the current diagnostic protocol for recall 25v-274 is insufficient to identify terminal manufacturing defects in the connecting rods and crankshaft of the l87 6. 2l v8 engine. The "remedy" of higher-viscosity oil failed to prevent the exact catastrophic loss of propulsion the recall was intended to address. The replaced engine is available for inspection upon request by the NHTSA office of defects investigation.

On or about Tuesday, February 3, 2026 at 12:20 cst, at the Chevrolet dealership in libertyville, IL; I presented my 2023 GMC sierra to “manny” at said dealership due to the vehicle instructing me to do so because of dtc codes displayed indicating a failed def tank. I was told a technician would be able to diagnose the vehicle that afternoon. Makemodelyearvin Gmcsierra2023 [xxx] day 1: came and went with no contact from the service department as promised. Day 2: Wednesday, February 4 came with – again – no follow-up from the dealer. When I called I was told there were “no notes in the service order” and “the tech has gone home. ” day 3: Thursday morning “manny” called to tell me nothing was done and nothing could be done. I was told to “call gm” and complain about my problem. This is how gm treats its customers. This is how gm treats its repeat customers. This is how gm treats its customers who buy their extended warranties. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

P1098 code for coolant control valve malfunction causing a radiator leak. Should be covered under warranty, but wyatt johnson in clarksville tennessee giving me the complete run around trying to get me to pay $3500 for a radiator replacement.

While traveling northbound on I?65 on Saturday, 1/31, the 6. 2l v8 engine in my 2023 GMC sierra at4 experienced a sudden and complete internal failure. My husband was driving and I was in the vehicle with him when the engine lost all power without any warning lights, messages, or prior symptoms. We were only able to coast into a very busy on?ramp merge lane before the truck died completely, leaving us stranded in an active traffic area for over two hours on one of the coldest days of the year, which created a significant safety risk for both of us and for other drivers. My truck was towed to the dealership. They inspected the vehicle, confirmed it was a full engine failure, and replaced the engine under warranty. The failed engine only had just over 37,000 miles on it at the time of the incident. Gm was notified through the dealer’s warranty process. No other agencies have inspected the vehicle.