2023 GMC SIERRA 1500 Complaints

[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)

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.

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.

While driving down the highway at night my front grill deflector broke off hitting my windshield and flying into the road. Thankfully there was no one behind me but it scared me quite a bit and could have caused me or someone else to crash

It was the Chrome Grille Deflector and is available for inspection. I was driving down a long road at roughly 50 mph when all of a sudden the grille deflector detaches from my bumper and hits my windshield causing me to swerve thinking I had hit something. I was almost in an accident. I believe there is a recall for this exact thing but only for 2022 models not 2023. No it has not been inspected I tried to call GM to get guidance and see if it could possibly be covered seeing as it is a manufacture error but was denied. One small piece that has been recalled on other vehicles but mine is causing me to almost pay $900 dollars. I have yet to replace the part

As I was driving down the highway the hood front molding flew off and took a chunck of paint off my GMC 2023 AT4, hitting a elderly ladies windshield we pulled over there was no damage to her car thankfully, she was very shakin and gave me an ear full. I have reached out to GMC even took it in and left it overnight and they say it is not under the recall and it will cost $1200.00 to fix. We currently own 3 GMC's, this one is mine (a woman) and she is my baby. I do not think it is fair that my truck matches the exactly damage you see on the trucks on the recall list, a service man also told me that they replaced one of them that was recalled and shortly after it to broke and flew off. If there is anything someone can do help, I know I am not the only one this is happening too. Thank you J

The plastic upper rail glass guide frame on the rear sliding window assembly of my 2023 GMC Sierra developed structural micro-cracks during normal vehicle operation. This manufacturing defect is a known issue tracked internally by the manufacturer under Technical Service Bulletin (TSB) #18-NA-383.This structural failure allows severe water intrusion into the passenger cabin. The leaking water runs straight down the inside back wall of the cab, completely flooding and corroding sensitive, factory-installed electronic safety modules mounted directly beneath the leak path.This continuous water intrusion caused the catastrophic electrical failure and corrosion of the video processing control module located behind the rear seat. The sudden failure of this module completely disabled the rearview digital mirror camera and the 360-degree perimeter driver assistance cameras, creating immediate blind spots and an active driving safety hazard while operating the vehicle.The vehicle was inspected and repaired by an authorized dealership, confirming the rear window leak as the direct cause of the electronic destruction. The out-of-pocket cost to replace the water-damaged safety components was $2,747.00. Because the manufacturer refused to cover the replacement of the defective rear glass assembly, the structural leak remains unresolved. This active water intrusion continues to flood the cabin, creating a health hazard via mold growth and guaranteeing that the newly replaced safety cameras will inevitably short-circuit and fail again.

the vehicle is actively presenting severe mechanical symptoms that make it entirely unsafe to operate on public roads. Specifically, it exhibits a violent shuddering and vibration through the cabin when coasting or cruising at highway speeds. Furthermore, it undergoes aggressive jerking, harsh engagement, and dangerous hesitation the moment I press the gas pedal to accelerate or merge.

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.

The transmission control module failed. The dealer said a I a high voltage alarm signal code. This was the diagnostic inform received from the dealership service department. Primary]: MDIAG : MISC. VEHICLE DIAGNOSIS. CHECK ENGINE LIGHT ILLUMINATED AND GETTING MESSAGE FOR SERVICE TRANSMISSION, UNABLE TO SHIFT. PLEASE CHECK AND ADVISE * Repair items per diagnosis: FOUND P07B4 STORED IN SYSTEM. VERIFIED WIRING OK TO GEAR SHIFT CONTROL MODULE. SI STATES IF WIRING GOOD TO REPLACE GEAR SHIFT CONTROL MODULE AND IF CODE RESETS TO REPLACE ECM. RECOMMEND STARTING BY REPLACING GEAR SHIFT CONTROL MODULE The truck would not shift or go into gear at all. This was concerning because the transmission could have stopped shifting while I was driving myself and my children around. This warning light came on while I was driving on the highway. My vehicle has about 58,000 miles on it and is still under powertrain warranty. But the dealership is saying this repair isn’t included.