GMC Sierra Complaints (2026)

171 consumer complaints on file.

#11757030August 14, 2026
ENGINE
The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving 70 MPH and depressing the accelerator pedal, the vehicle started decelerating unintendedly. The message “Engine Power Reduced” was displayed. A dealer was contacted. The vehicle was taken to a dealer where it was diagnosed and determined that the engine needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure and opened a case. The approximate failure mileage was 6,028.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756457August 12, 2026
ENGINE
The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving 45 MPH and depressing the accelerator pedal, the vehicle slowed down unexpectedly. The vehicle then lost power while stopped at a traffic light. No warning light was illuminated. The vehicle was turned off and restarted, and the vehicle operated as intended. The vehicle was taken to the dealer, where it was diagnosed and determined that there were metal shavings inside the oil pan and the engine needed to be replaced. The engine was replaced twice. The manufacturer was not notified of the failure. The approximate failure mileage was 3,202.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755698August 9, 2026
ENGINE
Driving on the highway near Rockport, WA, when vehicle suddenly loss propulsion, engine light appeared, and vehicle went into transport mode enabled. Without causing an accident, I was able to pull to the side of the road. Once I put vehicle in park, it shut off and displayed, “Tranport Mode On. Vehicle would not start and was towed home. My son-in-law was able to disable transport mode, but vehicle still will not start. Will notify dealership on Monday.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755699August 9, 2026
ENGINE
Driving on the highway near Rockport, WA, when vehicle suddenly loss propulsion, engine light appeared, and vehicle went into transport mode enabled. Without causing an accident, I was able to pull to the side of the road. Once I put vehicle in park, it shut off and displayed, “Tranport Mode On. Vehicle would not start and was towed home. My son-in-law was able to disable transport mode, but vehicle still will not start. Will notify dealership on Monday.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755712August 9, 2026
ENGINE
2026 Denali, 6.2, failed after getting off express way while on my way for a fishing get away and pulling my boat. NO warning lights, noises, nothing. Came to a stop sign and at the last second slammed into park. Dash went black, 10 seconds later would come back on and try to start, then the dash goes black. Sheriff pulled up 20 or so minutes later and told my wife to get back into the vehicle as she was directing semis and other cars to go around. Towed to a chevy dealership 13 miles away. After Running tests on the truck, came up blown engine. 7600 miles. 5 hours later we left with a loaner and able to continue on with our plans. I do thank the dealership for their help and loaner. 23 business days later they delivered my truck to my house and returned in the loaner. After all my investigating on these engines, I will not be buying another one. Time for GM to invest some of their profits into finding the problem!
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755572August 7, 2026
ENGINE
I have a 2026 GMC Sierra 1500 with the 6.2L engine. I purchased it on [XXX]. On [XXX] with 13,000 miles on the truck the engine started making a bad noise from the lower end of the motor. I immediately took it to the dealer Randy Wise Buick GMC in Fenton Michigan. They diagnosed it as a spun bearing and had to replace the engine. I just got it back today August 7th 2026 INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755200August 6, 2026
POWER TRAIN
The contact owns a 2026 GMC Sierra 1500. The contact stated that while her husband was driving approximately 10 MPH, the vehicle unexpectedly shut off and independently shifted into park(P). The contact stated that previously, while the vehicle was idling in a parking lot, with air conditioner activated, the Auto START/STOP feature engaged, and the vehicle shut off. The message “Service Transmission” was displayed. The vehicle was taken to a local dealer and was diagnosed with transmission failure. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 2,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755350August 6, 2026
STEERING, SUSPENSION, SERVICE BRAKES
Ongoing issues with Steering pull to right, and brake pull to hard right when applying brakes, which also turns steering wheel to right upon application. Have to keep steering wheel towards left with constant pressure to go in straight line and when braking. Driver has to be aware of changing road conditions that could affect that. Multiple inspections at multiple dealers have found no obvious issues, and multiple alignments performed, with tires also being replaced have had no success in correcting issue. Front suspension starting to feel loose due, and rear suspension squeak when going over bumps. Also recently found rear axle is shifted slightly to right. Suspect all are related. No parts replaced to date other than the tires. Happens daily. No accidents to date. Daily driver with long trips at times. Steering pull Issue has present since new but everything else has occurred since about 1800 miles and has progressively become worse. Conditions becomes worse at highway/freeway speeds of 65 to 80, but occurs as low as 10mph. Going back to 3rd dealer to look at it again. Truck is 2026 with 10,583 miles.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755053August 5, 2026
POWER TRAIN
I am submitting this complaint to report what I believe is a serious safety-related defect involving the General Motors 6.2L L87 V8 engine installed in my 2026 GMC Sierra Denali. On July 10, 2026, while driving on a public highway near Bogata, Texas, the engine suddenly began making severe mechanical noises before catastrophically failing without warning. The engine seized completely while the vehicle was in motion. At the time of failure, the truck had only 13,517 miles. The sudden loss of engine power left my wife and me stranded on the roadside. Had this occurred while crossing an intersection, merging into traffic, passing another vehicle, towing a trailer, or traveling in heavier traffic, the consequences could have been far more serious.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11754782August 4, 2026
ENGINE, ELECTRICAL SYSTEM, FUEL/PROPULSION SYSTEM
I was driving on 96 W. in slow traffic on the freeway when the vehicle put itself in neutral and shut off
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753938July 31, 2026
ENGINE
Engine died while driving at higher speed on interstate. Barely able to pull to emergency lane before truck stopped. No warning of any issues with it. Had towed to dealership. Dealership confirmed 6.2 engine was faulty. Engine replaced under warranty. Truck only had 1207 miles on it when engine died.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753455July 29, 2026
ENGINE
While traveling from [XXX] to [XXX] for vacation, I was in [XXX], and when I pulled off the interstate and came to a stop sign the vehicle quit. At first, I was unable to restart the Vehicle, but after sometime I got it started and was able to pull it off the road while the engine was making very loud clattering noise and the vehicle would not stay running. Prior to this there were no warning, lights or indications that the engine was going to quit. I checked the engine oil and it was full. I had the vehicle transported to a GMC dealer in [XXX], where it was diagnosed as requiring a new engine. The vehicle is a 2026 GMC Sierra 1500 Denali purchased in December 2025 and has 8,865 miles on it. A little over 4000 miles I had the vehicle oil changed at Starling GMC Titusville Fl. At the time of my service visit, I asked the service writer, [XXX] to check the engine idle because at times it seemed to run a little rough and it quit while pulling in my driveway one day. [XXX] advised me that there is no idle adjustment on the vehicle, so I said I’ll just keep an eye on it. There were never any indications of an engine problem prior to this or even as of now there are no warnings displayed on the instrument panel. I also subscribe to onstar and it indicates everything in the vehicle is normal with no issues. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753614July 29, 2026
ENGINE
6.2 l just blew up per dealership
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11752991July 27, 2026
TIRES:SIDEWALL, TIRES
No Incident Occurred. Tire Size 275/65R20. Tire Pressure Fluctuating between 59 and 71 PSI. 3 of 4 tires appear to have a defect. Was detailing the vehicle on 7/26/26 and noticed a tear in the Side wall on the Passenger side rear tire. About 3/4" to 1 inch away from the rim along the sidewall. Running parallel with the rim for about 4". Found similar defects and indentation lines on the Passenger side front and Drivers side rear, in varying lengths around the rim. Vehicle has Not Towed, had a Load in the bed or used off road. 1,897 miles all Pavement Mixed HWY and Street use. Vehicle was Purchased 6/25/26. Scheduled for Service 7/28/26. Will have the Dealer look at the tires.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753107July 27, 2026
ELECTRICAL SYSTEM
The telematics module for the OnStar system continues to stop working, I have had this truck in a dealership service center multiple times for them to reset the system (instead of replacing the defective parts). Along with the infotainment system not working properly (cuts in and out, blinks on/off, delay in actions) Doors unlock while driving, front/rear cameras come on when I stopping at an intersection, I have given them documentation of the diagnostic reports from dealerships
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11752669July 24, 2026
ELECTRICAL SYSTEM
The contact called on behalf of an insurer who owns a 2026 GMC Sierra 2500. The contact stated that 15 minutes after the vehicle was parked and turned off, a neighbor informed the owner that the vehicle had caught on fire. The owner and the neighbor extinguished the fire using water hoses. The contact stated that the fire originated under the rear passenger’s side seat and was caused by an overheating amplifier that had short-circuited. No warning light was illuminated. The Fire Department responded to the scene and filed a report. There was no Police report filed. There was no injury or property damage. The vehicle remained parked, and the owner intended to return the vehicle to the dealer. The owner was provided a loaner vehicle. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure, and a case was opened, but no assistance was provided. The failure mileage was approximately 9,000.
Crash:
No
Fire:
Yes
Injuries:
0
Deaths:
0
#11752717July 24, 2026
ELECTRICAL SYSTEM, VEHICLE SPEED CONTROL
6 month old, 9,000 miles 2026 Sierra 1500 with Duramax 3 liter suffered an engine control module failure 4 hours into a 12.5 hour drive home from family vacation. First a transmission service warning flashed, then an emissions system failure with a forced speed reduction warning. This happened with two children and a dog in the vehicle. OnStar did diagnotics and said I had to see a dealer. Fortunately one was nearby and they determined the engine control module needed to be replaced--but i was 8.5 hours' drive from home with kids and dog and would have had to stay for 2-4 days awaiting parts and repair. I traded the truck at the dealer for a new vehicle and drove that home. This was a major safety concern traveling with children and a dog on a nearly 100 degree day. And it was a brand new vehicle.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11752469July 23, 2026
POWER TRAIN
When going up my 5% grade driveway the truck has slammed into “park” while moving two times. The car turns off as it slams into park and a “ service transmission” warning is on the dash. It leaves small skid marks from doing this while moving. It has 1790 miles on it. Dealer has had it a week and says they cannot duplicate the issue. Google search seems to indicate many trucks have had the same issues going up an incline.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11751712July 21, 2026
UNKNOWN OR OTHER, ENGINE
I bought the truck with 2 miles , shut off on me within 1,300 miles wouldn’t turn on , supposedly it was a bad fuse that was burned out , Second time it shut off on me again , all my sensors were going off and on and truck wouldn’t turn back on , they told me they couldn’t figure out the problem evaczue they had disconnected the battery and it erased all the codes 3rd time , they changed my oil and they forgot to torque the screw back correctly and all the oil spilled and cost my engine to lock up and mess up , they replaced the motor with a new one 4th time , supposedly it needs a replacement for a catalytic converter which is being replaced now as we speak or sometime this week
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11750542July 15, 2026
FORWARD COLLISION AVOIDANCE: WARNINGS, FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING, BACK OVER PREVENTION: WARNINGS
I purchased this new full-size heavy-duty pickup, and at purchase the selling dealer installed a 3-inch suspension lift kit with 37-inch tires on 22-inch wheels as a paid dealer upfit. The lift kit manufacturer publishes a maximum tire size of 35 inches on a 20-inch wheel for this kit; the tires and wheels the dealer installed exceed that spec. The lift manufacturer confirmed directly that they would never approve exceeding the 35-inch tire / 20-inch wheel recommendation. The dealer's assistant manager confirmed that NO calibrations of any kind were performed after the lift and 37-inch tires were installed, and said nothing is recalibrated when a lift is done with 37-inch tires. This vehicle is factory-equipped with forward collision alert, automatic emergency braking, front pedestrian braking, lane departure warning, and automatic high-beam control. These crash-avoidance systems rely on forward-facing camera and sensor aim, which depends on ride height and suspension geometry. A 3-inch lift with 37-inch tires materially changes that geometry. With no calibration performed, there is no assurance these safety systems are aimed or functioning to spec. The truck was also never aligned after the lift and the tires are cupping. The headlights were never re-aimed for the higher ride height, and the speedometer was never recalibrated and reads inaccurately. The oversized tires also contact the body. The left front tire has torn into the front fender, the fender well is misaligned, and it is forcing the lower front edge of the driver's door out of alignment. The dealer's only proposed remedy is to keep cutting the fender wells; the trimming already done has exposed electrical wiring behind the wheel well to mud, water, and road debris. I am reporting this because the assistant manager's statement suggests it may be the dealer's standing practice—other customers may be driving lifted trucks with uncalibrated crash-avoidance systems without knowing it.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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