Table 1 shows one common power train related problems of the 2026 GMC Sierra 1500.
| Problem Category | Number of Problems |
|---|---|
| Power Train problems |
While driving the truck it randomly shuts down, message on dash says shift to park to restart. No check engine light comes on or any other message. When it does this, the truck goes into park. It has been to the dealership 3 times and has not been fixed!.
On 10/15/2026 I was making a slow right-hand turn up a slight incline into a parking lot when the vehicle braked very hard and the transmission made a grinding noise. I looked at the dashboard, and it was showing that the truck shifted into park while I was driving. The electronic brake engaged as well. I tried putting the truck back into drive, but it would not go into drive. On the dash there was a service transmission warning. The push to start engine button still had the green led on as if the vehicle was running. I pushed the start engine button and the engine started (I didn't realize until now that the engine had shut off). At this point the truck would shift into drive. Another point of note is that I had turned off the auto stop feature. I do this every time I start my trip. The truck will be looked at on 10/16/2026 by the dealership. I did report the problem to the service department of the dealership. This incident was the first time it ever happened and there was no warning.
While driving on a public road, the 6. 2l l87 v8 stalled without warning. There was heavy smoke and an oil trail of about 300 yards behind the truck. The engine would not restart, and the transmission would not shift into neutral. The truck was moved a short distance off the road and towed the next day to the selling GMC dealer. Odometer was 4,663 miles. Oil life remaining was 38 percent. The truck was stock, with no modifications, and was operated on premium fuel. No warning lamp was noticed before the stall. The failed engine is at the dealer and currently under inspection. The dealer inspection is not finished, and no written cause has been provided. This is a sudden loss of propulsion. Please associate this report with engineering analysis ea26005 concerning connecting-rod and crankshaft failures in the gm 6. 2l l87 engine.
While turning right and at a slight incline the truck engine turned off, the transmission made a grinding noise, the truck went into neutral and the dash stayed “press start button”. This is the second time this has happened within 5000 miles of the struck being purchased. Several others have reported the exact same issue on facebook forums.
Engine stall on the highway.
Very similar to NHTSA complaints 11752469; ?11762072?; 11761966?; 11761844; ?11755200 while turning left into my 6 degree inclined drive at a slow rate of speed under 5 mph, my 2026 GMC sierra slt x31 with 1500 miles suddenly slams into park and shuts down. "press start" shows on display and am able to start the truck. Twice the "service transmission" light has displayed. I took it to the dealer after two incidents and they could not replicate. Since getting it back from the dealer, I've had six more incidents and am taking back to the dealer with more information for them. The last incident, I was prepared for it and felt the truck begin to shut down and slammed on the brake before it shut down.
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.
Vehicle: 2026 GMC Sierra 1500 at4 (3. 0l lz0 duramax diesel) current mileage: ~16,500 miles check engine light status: no check engine light active description of incident & symptoms: •interstate incident: while driving at highway speeds, a severe drivetrain vibration occurred (felt like a rear wheel weight flew off). •dashboard warnings: within 5 minutes, intermittent "traction control" and "forward collision warning" alerts appeared on the dash, accompanied by a sudden drop in engine power. •engine noise & idle: once safely pulled over, the engine exhibited a loud mechanical knock and a very rough, unstable idle. •extended crank: after shutting the engine off and waiting a few minutes, restarting the truck took roughly twice as long as normal (long crank/delayed start).
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.
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.
The contact owns a 2026 GMC Sierra 1500. The contact stated that while hauling a trailer and making a left turn at 5 mph, at a busy intersection, the message "shift to park" displayed, and the vehicle lost motive power. The vehicle was restarted. The contact stated that the failure was persistent. The local dealer was notified of the failure by phone. The vehicle was taken to the dealer, where it was diagnosed that the telematics module had failed and needed to be replaced. The vehicle was repaired. The failure mileage was approximately 3,900.
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.
The contact owned a 2026 GMC Sierra 1500. The contact stated that while slowly driving up a slightly inclined driveway and making a left turn, the engine shut off. The contact stated that either the parking brake activated, or the vehicle suddenly decelerated. The contact stated that the failure had occurred several times, with three 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 vehicle was not repaired. The vehicle was later traded in for an identical vehicle. The manufacturer was notified of the failure.
While driving on the highway, the steering became much more stiff, and then I heard metallic clanging sounds for a few seconds. The dashboard said press start to start vehicle. I pressed start while going 30 miles an hour and all lights and instrument clusters went black. I pulled into the grass median where the truck would not start or shift gears. Truck was towed to a GMC dealership.
5/08/2026: I stopped outside my garage. I then placed the truck in park and exited the vehicle while running. I went inside my garage and several minutes later, heard a crash. The truck had driven forward while unattended, and crashed into the corner of my garage, causing damage to both the building and the truck. Truck indicated it was still in park upon reentry. 5/11/2026 in a separate incident 3 days later, while driving at approximately 50mph, truck engaged in an automatic braking event with no discernible cause. Simply applied what felt like 100% braking for a split second, then released. 5/12/2026: truck taken to GMC for investigation. No codes in any modules detected. 9/20/2026: vehicle reports transmission fault, states it should not be driven. 9/21/2026: towed to GMC dealer. Found codes p17a8 and p189d and diagnostic code 6906361, internal fault within gearshift control module. Requested GMC pay for damage resulting from collision, as clearly the unattended driving appeared related to gearshift control, but was refused. GMC stated that unattended driving was not possible and did not result from the detected failures.
Bought the vehicle brand new at the end of April. 2 weeks later and at 557 miles, the engine had a lifter failure and needed to be replaced. One day after picking it up after the engine replacement, a fuel injector went bad and needed to be replaced. About 2 days ago, the check engine light lit up, and the GMC app said it was a code for the transmission system (popped on after attempting to remote start the vehicle, although the light did shut off on its own the next day after a software update on the vehicle).
I bought the vehicle brand new in April 2026. On may 3rd, approximately 2 weeks after I bought it, I experienced a lifter failure that caused metal to get into the oil pan/engine and the engine needed to be replaced. About a month later after repairs were complete, I picked up my vehicle on a Friday night, and the very next morning, had issues again. Took it back to the dealer and a fuel injector went bad and needed to be replaced. I recently attempted to use the remote start feature and as soon as it fired up, the engine cut out. I went to start it again and the check engine light came on. My GMC app said the code was transmission related, although it cleared on its on the next morning after a software update.
Truck was sold to me and the dealership said the truck did not have the defect and the oil was changed to a thicker oil as a precaution. 4,000 miles later the engine failed, was diagnosed as catastrophic engine failure due to the known recall, and was replaced, new engine is now making the same rod knocking noise.
The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission independently shifted to park or neutral. The contact stated that the failure had occurred while driving at slow speeds. The contact stated that during one failure, the brakes independently activated, and the vehicle shut off. The contact stated that while attempting to restart the vehicle, the vehicle started. The contact stated that the failure was persistent. The dealer was made aware of the failure by phone. The vehicle was taken to the dealer; however, the diagnostic result was not provided. The failure mileage was approximately 500.
I bought the truck brand new from gregg young in atlantic, IA. While an hour into the drive home, the truck began shuttering as if the transmission was having problems finding the gear. I immediately made an appt with their parent dealership of gregg young in plattsmouth, ne. They had the truck for a week and couldn’t duplicate the transmission issues after I reported several occurrences and symptoms, they also didn’t provide a service invoice of the work performed while I found was unusual. As I was driving the truck home from repairs it started hesitating and having difficulty finding gears. I didn’t think much of it since the dealer claimed there was nothing wrong. This past weekend while going 65 mph down the freeway the transmission started shuttering as well as the truck and the tires began to lock up to the point of almost losing control, there was also metal on metal noises. I had to pull over and luckily driving real slow I made it home. The gregg young dealership were I bought it will take no responsibility and provided falsification since no service was provided nor upon checking app gps there was no indications it left the dealership while in there possession for a week, will contact GMC in the am since this has now become a safety issue and there was metal on metal contact noises and the serious risk of a crash.
Transmission cooler line blew out.
The motor on my 2026 GMC sierra stalled 2 weeks ago with a p0016(crankshaft position sensor issue). Was able to clear code and limp home. Vehicle did stall on a busy road and stop abruptly. Scheduled service and was advised to drive it in. Was experiencing irregular idle when warmed up, and a slight hesitation in the pedal. Service advisor started the vehicle and claimed no codes, and everything appear ok. Later in the afternoon the service advisor called to inform me that the vehicle had a siezed engine and had siezed during a test drive on the highway. Currently waiting on warranty information, and engine replacement information but I've been informed it will require a whole new engine. This is the same 6. 2l l87 v8 that has been in near constant recalls from GMC over the last 6 years.
Engine lock up with 5018 miles on, it is a the 6. 2 motor rod and crank bad.
The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving 5 mph, the vehicle independently shifted into park(p). The check transmission warning light was briefly illuminated. The failure was a recurring failure. The dealer was contacted. The manufacturer was contacted by phone and made aware of the failure. The failure mileage was approximately 2,000.
While driving at approximately 60 mph on an open road with no obstacles present and no braking input, the rear wheels spontaneously locked up without warning. No brake pedal input. No warning light prior to the event. No obstruction in the road. The vehicle has been subject to an active manufacturer recall for rear wheel lockup due to transmission control valve failure. The dealer's own diagnostic system generated a report showing six active fault codes in the following days including lost communication with the brake system control module and transmission control module. These codes were not addressed on the repair order. The dealer attributed the lockup to an automatic emergency braking activation without diagnostic confirmation and performed no repair. The manufacturer's own internal bulletin dated January 22, 2026 acknowledges the exact fault codes present on this vehicle as a known defect. The dealer cited this bulletin to dismiss the concern while stating no problems exist. A persistent brake noise has been confirmed by two separate authorized dealers across three visits with no repair performed at any visit. The vehicle has required five dealer visits in 77 days of ownership with 1,729 miles. The defect remains unresolved and poses serious risk of loss of vehicle control at highway speed.
My engine seized up on me on the highway. I was stranded and couldn’t start the vehicle and it was freezing outside.
Vehicle stalled in busy intersection in mckinney texas , unable to start are shift into a neutral position on transmission to remove from extreme dangerous intersection, sheriff advised that road side assistance that was contacted is not going to be in time (90min)to keep from causing an ongoing traffic backup , sheriff dispatched their own towing service to resolve the situation from getting extremely dangerous . Vehicle and my wife was towed to mckinney Buick GMC dealership.
My 2026 GMC at4 3. 0l duramax had a catastrophic engine failure on Sunday, February 8, 2026. It went into reduced acceleration and also fault code po6dd. Thankfully I was not on a highway. The truck would not run over 45 mph on flat ground, and then by the time I got it to a safe location 5 miles away it would not run over about 30mph. This obviously resulted in the truck being towed to a dealership. I have been told the entire engine will be replaced. Upon further reading, I suspect this is a thrust bearing failure that is a well-known issue in this lz0 duramax engine. What I have read, this issue is occurring mostly on trucks built from may-sept 2025, and my truck has a 7/2025 build date. This could have been major safety hazard if the engine had failed in a major freeway/highway.
I am submitting this complaint regarding a recurring transmission issue in my vehicle. The transmission consistently jerks and shifts erratically, particularly in the morning during initial operation when at cruising speeds of about 50-75 mph. This behavior occurs when the transmission temperature is below approximately 100°f and happens on a daily basis. The gear changes feel harsh and abrupt, kind of like it doesn’t know what gear to be in its raising concerns about both drivability and long-term transmission reliability. I brought the vehicle to an authorized dealership for inspection. After evaluating the issue, the dealer informed me that the behavior was due to the vehicle being in “sport mode. ” however, this explanation does not resolve the concern, as the severity and consistency of the jerking appear abnormal and occur regularly under the same temperature conditions. Given the persistent nature of this problem and its potential safety implications — especially during acceleration and low-speed driving — I am requesting that this issue be formally documented and investigated. Thank you for your attention to this matter.
Odd noise from bell housing area at 1200 miles that went with engine rpm. Took the truck in to the dealer and they said they couldn't recreate it but to bring it back in if it returned. Jan 27th at 5200 miles on the truck, I was driving down the highway at 60mph and got a reduced acceleration message on the dash along with a check engine light. Brought it to the dealer and was informed it was a bad thrust bearing and needed and engine and turbo replacement. Still waiting for the truck to be done.
26’ GMC Sierra 1500 at4 3. 0l duramax experiencing harsh shifting occurring sporadically while accelerating and deceleration. More frequent and severe during quick deceleration. Severe clunking/rear wheel lock up while reversing. Very repeatable. Truck was a dealer demo and had 2400 miles on it when I bought it last week. Took it in to the dealer today and they said I need a complete new transmission.
I heard a loud metallic knock that was not consistent with normal engine noise. I noticed the oil pressure was on the lower end of the scale but not abnormal based on how it is displayed. I decided to take the vehicle to the dealer ASAP for an oil change (that was coming due) and discuss with them. I drove roughly 20 miles from start of noise until delivery at the dealer. The truck gave me a "reduced acceleration, drive with caution" message 10 miles prior to the dealership but no associated lights, engine codes, check engine light or associated alerts on the mygmc app. Dealership found oil pressure ranging between 4-8 psi, and a failed oil pressure control solenoid, heavy metal debris in the oil pan including parts of the thrust bearing and oil squirter. Entire engine and turbo replacement was required. Truck had 143 hours on the engine and 6,300 miles. It was produced in August of 2025 with a purchase date of 17 October 2025. Produced: 8/25 purchased: 10/17/25 failed: 12/30/2025 returned with new engine: 1/23/26.
2026 GMC sierra elevation x31 with 3. 0 duramax diesel engine, 132-miles, thrust bearing 1. 53-mm out of tolerance requiring engine and turbo replacement. Engine build date 25219 (07 Aug 2025), vehicle assembly date August 2025, purchased 10 oct 2025, entered service for engine and turbo failure on 11 Nov 2025, returned 10 Jan 2026.
The powertrain/transmission is malfunctioning. The vehicle shutters, vibrates, and surges forward when coming to a stop, as if it wants to take off on its own. These symptoms began within the first couple of days after purchasing the vehicle on xxx. The valve body was replaced, but the issue continues. The vehicle is available for inspection. Gm case number: xxx dealership tac case: xxx this creates a serious safety risk. When stopping, the truck shutters and unexpectedly tries to lunge forward, which could cause a collision with another vehicle or pedestrian. The unpredictable movement makes it dangerous at intersections, stop signs, and in traffic. The dealership has reproduced the issue multiple times and performed diagnostics, but the shuttering and surging continue. The vehicle was last inspected around xxx. On xxx, I called gm to speak with [xxx] for an update on when a gm representative/technician would inspect the truck. I was told the case had been closed even though no resolution or inspection occurred, and [xxx] never called me back. No other agencies have inspected it. There were no warning lamps. Symptoms began within days of purchase and include shuttering, vibration, surging forward when stopping, and inconsistent acceleration. These symptoms occur daily and have worsened over time. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).
My 2026 GMC 1500 is equipped with the 2. 7l l3b & 8l90 transmission. At approximately 1000 miles, I noticed that in 2nd between 2700-3200 rpm, a vibration could be felt throughout the cabin and would occur whether with or without throttle application. I am able to recreate the issue during hard acceleration or placing in manual mode. No matter the vehicle mode selection (sport, normal, snow, tow/haul, etc. ), the issue still persists. I took the vehicle to a local GMC dealer at approximately 6k miles to diagnose. I requested that we test drive another 1500 with the same 2. 7l and transmission. They brought out a 2026 elevation quad cab with the 2. 7l; less than 20 miles on the odometer. The same vibration was present in 2nd gear at same rpm band. I requested that the issue be escalated to a local gm rep. For further investigation. However the response from the dealer was inadequate and basically stated that no warranty work would be considered because it seems to be “normal operation”.