2023 GMC SIERRA 1500 Complaints

The truck side toy down shift and the accelerator was very high…. When I was going to park the reverse was not shifting…

Upon accelerating on the freeway, rear wheels locked up completely almost causing me to hit multiple vehicles. Was repeatable and was able to record the event. Manufacturer claims unable to reproduce and bring back if it happens again. No lights were set.

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.

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.

Driving down the interstate and the front trim bezel on the hood flew off. The plastic clips broke from underneath. GM had a recall on this same issue in 2022 but not 2023 yet. Could of had an accident with the piece flying off at interstate speeds.

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.

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.

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

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.