GMC Complaints

Vehicle ran out of fuel and became disabled in an active roadway/exit ramp. The vehicle retained 12-volt electrical power and the dashboard and electronic controls remained operational. With the brake pedal depressed and the ignition/electrical system on, I attempted to shift the transmission from Park to Neutral so the vehicle could be pushed out of traffic. The vehicle repeatedly displayed “Conditions Not Correct for Shift” and remained locked in Park because the engine was not running. There appears to be no driver-accessible mechanical/manual override that allows the transmission to be placed in Neutral when the engine cannot run. As a result, a disabled vehicle with functioning electrical power can remain physically immobilized in a live traffic lane, creating a collision hazard and preventing occupants or bystanders from moving it to a safer location. This condition could occur not only from running out of fuel but potentially from any engine failure that prevents the engine from running. I believe the inability to place a disabled vehicle into Neutral under these circumstances presents a safety hazard.

2020 GMC Sierra 1500 AT4, 3.0L LM2 Duramax. In service 08/13/2020. Five glow plug failures on five different cylinders in under 19,000 miles, all at one GM dealer, all part 24000504: Cyl 1, 10/21/2024, 38,650 mi, P0671, RO 13714, warranty. Cyl 6, 11/05/2024, 38,793 mi, P1330, RO 26665, warranty. Cyl 4, 11/29/2024, 39,683 mi, P133B, RO 57498, warranty. Cyl 3, 01/22/2026, 52,959 mi, P0673/P06C7/P133A, RO 100951, I paid $713.38. Cyl 2, 08/26/2026, 57,466 mi, P06C6/P0672/P1339, RO 115953, GM under N232430460. The first three came within 39 days and 1,033 miles. Every RO documents the same finding: high internal resistance in the plug, circuit tests good. The failure is internal to the plug. Glow plug failure on a diesel causes hard starting, extended cranking, no-start in cold weather, and startup misfire - risk of being stranded or unable to start. GM has documented this defect three times: PIP5762 (12/2020), TSB 22-NA-027 (2/2022), Special Coverage N232430460 (1/2024). All name an inadequate camshaft housing cover baffle plate weld, and all limit the remedy to cylinder 2. On the recorded walkaround for RO 115953 the tech stated my engine serial falls inside the affected population and my earlier failures were probably the same condition. GM replaced only the glow plug. The camshaft cover GM identifies as the cause is still installed; GM quoted me $5,100 to replace it at my expense. Four of five failures were on cylinders 1, 3, 4 and 6, outside that scope. If the bad weld passes oil into the PCV and intake path rather than only the cylinder 2 glow plug well, ingested oil would reach other cylinders. No RO shows anyone inspected the intake tract, charge piping, cooler, PCV separator, a removed plug, or a glow plug well. I ask ODI to examine whether the cylinder-2-only scope of N232430460 is under-inclusive, whether replacing the plug while leaving the cause installed is an adequate remedy, and whether repeated internal failure of part 24000504 warrants a recall.

I purchased a 2024 GMC Sierra 1500 Denali Ultimate equipped with the 6.2L V8 engine on XXX. The vehicle currently has approximately 25,000 miles. On XXX, the vehicle underwent the GM recall repair related to the 6.2L engine at Don Mealey Chevrolet. On XXX, approximately nine months after the recall repair, my family and I were traveling on the [XXX] with my two children inside the vehicle when the engine suddenly experienced a major failure. The vehicle became inoperable while we were traveling on the highway and had to be stopped and subsequently transported to Schumacher Buick GMC in [XXX]. The failure occurred unexpectedly while the vehicle was being operated normally. Having an engine failure while traveling on a major highway with my two children in the vehicle created a significant safety concern because of the potential for loss of power and the danger associated with becoming disabled in active highway traffic. GM has subsequently authorized replacement of the engine under warranty. The vehicle remains at the dealership awaiting completion of the engine replacement. I am reporting this failure because the vehicle had previously received the GM recall remedy for the 6.2L engine issue and subsequently experienced a major engine failure at only approximately 25,000 miles. The failure occurred approximately nine months after the recall repair. I am concerned that the previous recall remedy may not have adequately addressed the underlying condition associated with these 6.2L L87 engines. I am requesting that NHTSA document this failure as part of its investigation into 6.2L L87 engine failures and evaluate whether the existing recall remedy adequately addresses the safety-related engine failure condition. Vehicle information: * [XXX] GMC [XXX] 1500 Denali Ultimate * 6.2L V8 engine INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

So I spent many months trying to aquire a GMC Sierra Denali and with all the issues with the 20 - 24 6.2 engines we were assured by the dealer that all the issues were resolved with the 2025 6.2 models. So we spent big to aquire an 2025. So I bought one new. My truck had 8000 miles on it with 2 oil changes. So we booked a trip to [XXX] at considerably a large expense and loaded up our Harley's on my light aluminum trailer, less than 3.5k pounds and headed that way from [XXX]. We made it to [XXX] and spent the night. Next morning we were heading to [XXX] and the truck blew up on the XXX. We were pulled over on a very busy hi way and had to get truck and trailer towed back to [XXX]. We were stuck there for 3 days while GMC installed a rebuilt motor in my 83k truck and totally missed our entire vacation. On line it said GMC would cover hotel and 40.00 dollars a day food. I am so disgusted after being reassured that GMC had fixed the 6.2 and putting our life in danger blowing up on a major highway, and afterward GMC only gave us 200. For our inconvenience. Our room alone was more not counting the money lost on out trip accommodations. I am so completely disappointed with this truck that we bought new and spent more than we ever had on a vehicle, and am afraid of ever taking another trip in it. How can GM be allowed to do this to people. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2026 GMC Sierra 1500. The contact stated that while slowly driving up a slightly inclined drive port and making a left turn, the vehicle shut off and the parking brake was activated or the vehicle suddenly decelerated. The contact stated that the failure had occurred on several occasions with three separate identical vehicles, including the loaner vehicle provided by the dealer. During the failure, the messages "Press Start" and "Service Transmission" were displayed. The vehicle was taken to the local dealer who was unable to determine the cause of the failure. The manufacturer was notified of the failure. The failure mileage was 29.

Sunday XXX, we were riding in our 2022 Yukon Denali with my wife driving on [XXX] at the speed limit of 75 mph when the vehicle stumbled for a moment then returned to normal operation... a few seconds later the engine just died. No drive information center warning or check engine light, no funny noises or catastrophic banging. It just quit running. There was traffic on the highway but with my wife's quick reaction we were able to get off the highway to the breakdown apron without crashing. We called AAA and had the vehicle towed to the GMC dealer (Oxendale GMC) in Flagstaff. We were at this point about 200 miles from home in [XXX] City. On Wednesday, XXX, the service writer called us and informed us the engine was seized and would have to be replaced. We were aware of the NTHSA recall and had taken our vehicle in on XXX to have the recall (N252494000) and at that time we passed the pico test and the oil was upgraded to the higher viscosity and oil fill cap changed. We were sent on our way with no advisory the recall may not have fixed the underlying problem. GM has agreed to replace the engine. We filed a complaint with GM (GM case #XXX) Since this happened, we have been looking into this situation and discovered ours is not an isolated case. A lawyer told us that here have been more than half a million vehicles recalled and an unknown number of catastrophic engine failures just like our, but NTHSA has received less than 1000 complaints. I wanted to make sure that my experience was conveyed to you. An additional note - we special ordered this vehicle new and began to have recurring electrical problems with it shortly after we took delivery. GM offered us a buy-back or a 100,000-mile warranty to keep the vehicle. Since then have had the vehicle serviced at regular recommended intervals by Brdley Chevrolet in [XXX]. We have repair invoices for every service and Recall repair done. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

L87 recall was completed on 10/22/2025. On August 8th 2026 the engine developed a loud knock. It was taken to the dealership on 8/31/2026 after inspection it was determined that the engine had failed and needed to be replaced. There was no warning lamps that indicated there was an issue with the engine. The vehicle was still driveable when it was taken to the dealership. If the engine had completely failed while on the highway it could have caused a major incident.

2023 Yukon Denali, 6.2 Engine. Owner complied with first GM recall and the engine passed inspection. 8/16/26 Engine started making a knocking sound. 8/17/26 Yukon was taken to the dealership and diagnosed as complete engine failure. There were no warnings indicated on the dash. Yukon is currently still at the Dealership with no repair date issued. Today is 9/3/26. I have contacted GM regarding a possible buy-back. GM said they would email in 24-48 hours. I have not heard from GM and it is now 72 hours since my initial phone call.

1. My vehicle is having transmission issues with shuddering and shifting. M5U RPO code 8L90 transmission. 2. My safety and the safety of others is a concern if the transmission is not working as intended my vehicle could be at risk an accident that could be avoided. 3. The problem has not be reproduced or confirmed by a dealer I work on my own vehicles and I am going to repair this issue myself if able. 4. There are no trouble codes on my vehicle when scanned with an OBD2 scanner.

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving 70 MPH and looking in the driver’s side mirror, the contact became aware that an unknown object had detached from the vehicle. The contact was unaware that the chrome front grille deflector had detached until arriving at the residence. The dealer was contacted, and the vehicle was taken to the dealer to be diagnosed, and the contact was informed that the chrome front grille deflector needed to be replaced. The vehicle was not repaired. The contact associated the failure with NHTSA Campaign Number: 25V060000 (STRUCTURE); however, the VIN was not included in the recall. The failure mileage was 48,210.