2023 GMC Sierra 1500 Engine Problems

- vehicle started misfiring, ECM, valve timing code, throttle system code, data system, gateway, module,. Vehicle is available and currently at the GMC dealership for continued diagnostic. -this happened on the freeway and out of nowhere the vehicle started shaking, rough, losing power and acceleration, I had to cut someone off on the freeway just to get over to the right shoulder and turned off the vehicle called a tow truck and haven’t been able to use the vehicle since. Vehicle is unable to be driven due to safety issues of increased acceleration and loss of power, intense shaking. -the vehicle is at the dealership now, prior there was a diagnostic performed by a different dealer, and it has been confirmed. -the vehicle is at the GMC dealership now. -ECM check engine light came on prior to the vehicle misfiring and other codes coming up.

NHTSA ID

11755389

Incident

Feb 3, 2026

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.

NHTSA ID

11752365

Incident

Jul 4, 2026

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.

NHTSA ID

11751989

Incident

Jul 18, 2026

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.

NHTSA ID

11749583

Incident

Jun 10, 2026

Mileage

17,000 mi

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.

NHTSA ID

11749293

Incident

Jun 12, 2026

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.

NHTSA ID

11748693

Incident

May 24, 2026

While driving vehicle on state highway exit at approximately 55 mph a knocking noise started coming from engine then engine just died and would not restart. Engine was replaced under recall.

NHTSA ID

11748009

Incident

Jun 12, 2026

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.

NHTSA ID

11747281

Incident

May 4, 2026

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.

NHTSA ID

11747167

Incident

Jun 29, 2026

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.

NHTSA ID

11746738

Incident

Jun 25, 2026

[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)

NHTSA ID

11745455

Incident

May 18, 2026

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.

NHTSA ID

11744918

Incident

Jun 12, 2026

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.

NHTSA ID

11744192

Incident

May 22, 2026

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving at 15 MPH, the vehicle stalled. There was no warning light illuminated. The vehicle was towed to the dealer, where it was serviced, but the failure persisted. The vehicle was taken to another dealer, where it was diagnosed with engine failure. No further information was available. The manufacturer was not made aware of the failure. The failure mileage was approximately 103,000.

NHTSA ID

11742795

Incident

Apr 10, 2026

Mileage

103,000 mi

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

NHTSA ID

11741004

Incident

May 29, 2026

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.

NHTSA ID

11740911

Incident

May 26, 2026

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.

NHTSA ID

11740519

Incident

May 16, 2026

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.

NHTSA ID

11739416

Incident

May 13, 2026

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.

NHTSA ID

11739316

Incident

May 20, 2026

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

NHTSA ID

11737731

Incident

May 4, 2026

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.

NHTSA ID

11736021

Incident

Apr 1, 2026

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

NHTSA ID

11735431

Incident

Apr 12, 2026

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

NHTSA ID

11735062

Incident

Mar 30, 2026

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

NHTSA ID

11734753

Incident

Apr 17, 2026

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.

NHTSA ID

11732214

Incident

Apr 19, 2026