2026 GMC Sierra 1500 Problems

2026 GMC Sierra SLT with 3.0 Duramax diesel engine. While driving down the road with the cruise set to 55 MPH on 8/29/26, the engine started to run rough. I slowed down, but this did not seem to help; I sped up, and the problem persisted no matter what I did. Service traction control and service ESC displayed on the dash. I drove to the dealership; their service department was closed because it was Saturday. I took my salesman for a ride so he could witness the issue firsthand. He confirmed something was not right, and they put me into a loaner vehicle. The truck has 848 miles on it. Service diagnosed it as a fuel issue in cylinder 2, replaced the injector, but the issue did not go away. GM TAC team advised replacing the motor; that is what I am currently waiting on. The dealer has the motor and is awaiting the install.

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.

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.

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 at a stop light, the engine shut off to save fuel, but after releasing the brake pedal, the engine failed to restart. The contact shifted to park, and the engine restarted. The contact stated that the failure had occurred on several occasions after the fuel saving feature was deactivated. Additionally, the contact stated that the failure had occurred while slowing down and driving over a railroad track and hauling a trailer. The vehicle was taken to the local dealer on several occasions, but the failure was not duplicated. The manufacturer was notified of the failure. The failure mileage was 4,300.

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.

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)

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.

Fuel Filter and High pressure Rail System The truck started shuddering and began to go into limp mode also shifted into neutral byitself No It was inspected by the dealership shop and now insurance Check engine light came on and code P1089

The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle hesitated to maintain automotive power and was a potential safety risk for his wife and children. The message "Shift to Park and Restart Vehicle” was displayed. The vehicle was shifted into park(P) and back into drive(D) as a temporary fix. The vehicle was taken to a local dealer on several occasions to be diagnosed; however, the cause of the failure was unknown. The failure mileage was approximately 700.

In early June 2026 I discovered a sheared pin on the front control arm of my 2026 GMC Sierra 1500 AT4X (VIN [XXX]), sold to me new by Parks GMC, Kernersville NC, with a dealer-installed Performance Package modifying the factory suspension. I delivered the truck to Parks GMC for warranty repair. The dealer represented it as a 1-2 day job. The truck was out of service approximately 2 weeks. The dealer sub-contracted the work to a third-party shop (CCV). At pickup, the dealer provided written documentation stating the repair was NOT PERFORMED. Neither the dealer nor I has been able to obtain any documentation from CCV describing what, if anything, was actually done to the vehicle. THREE UNRESOLVED SAFETY CONDITIONS: SHEARED FRONT CONTROL ARM PIN — original failure, status of repair unknown and undocumented. TIRE-TO-BODYWORK CONTACT — front tires intermittently rub the inside of the wheel wells during normal driving and steering, causing visible damage to the plastic mud guards. Tire-to-bodywork contact creates risk of sidewall failure, sudden air loss, and loss of vehicle control. FRONT RIGHT SUSPENSION CREAK — loud, persistent creak from the front right suspension during low-speed driving and steering inputs. Present at service drop-off, never addressed. Consistent with a worn, loose, or improperly installed suspension component. I escalated to Parks GMC management and GMC Customer Assistance. Parks has not provided a written repair plan, no decision-maker has contacted me, and the only response has been "looking into it." GMC Customer Assistance declined to assign a District Service Manager. I am filing to document these suspension and tire safety conditions in the federal database against this VIN and to request NHTSA evaluation of whether further action is warranted. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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

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.

I was out one day for lunch and my brakes stopped working on my truck. I had the truck towed after I limped home in it. The master cylinder failed at 4,200 miles causing the brakes to fail. It was replaced by the dealership.

My 2026 GMC Sierra has an oil-canned roof from a touchless car wash because the sheet metal lacks structural rigidity. This caused the roof to buckle and caused a permanent fold in the roof of the truck. There is already documented issues for this exact problem on the newer GMC Canyons and Chevrolet Colorado mid-sized trucks. Bulletin for reference NHTSA Official TSB #23-NA-209 PDF. I leased the vehicle on 6/19/2026 and this happened on approximately 7/7/2026. The vehicle only has 1,480 miles on it as of this date.

The tailgate intermittently opens while driving or parked

In early June 2026 I discovered a sheared pin on the front control arm of my 2026 GMC Sierra 1500 AT4X (VIN [XXX]), sold to me new by Parks GMC, Kernersville NC, with a dealer-installed Performance Package modifying the factory suspension. I delivered the truck to Parks GMC for warranty repair. The dealer represented it as a 1-2 day job. The truck was out of service approximately 2 weeks. The dealer sub-contracted the work to a third-party shop (CCV). At pickup, the dealer provided written documentation stating the repair was NOT PERFORMED. Neither the dealer nor I has been able to obtain any documentation from CCV describing what, if anything, was actually done to the vehicle. THREE UNRESOLVED SAFETY CONDITIONS: SHEARED FRONT CONTROL ARM PIN — original failure, status of repair unknown and undocumented. TIRE-TO-BODYWORK CONTACT — front tires intermittently rub the inside of the wheel wells during normal driving and steering, causing visible damage to the plastic mud guards. Tire-to-bodywork contact creates risk of sidewall failure, sudden air loss, and loss of vehicle control. FRONT RIGHT SUSPENSION CREAK — loud, persistent creak from the front right suspension during low-speed driving and steering inputs. Present at service drop-off, never addressed. Consistent with a worn, loose, or improperly installed suspension component. I escalated to Parks GMC management and GMC Customer Assistance. Parks has not provided a written repair plan, no decision-maker has contacted me, and the only response has been "looking into it." GMC Customer Assistance declined to assign a District Service Manager. I am filing to document these suspension and tire safety conditions in the federal database against this VIN and to request NHTSA evaluation of whether further action is warranted. 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 after purchasing the vehicle, there was no Owner’s Manual in the vehicle. The contact inquired about the Owner’s Manual and was informed by the dealer that an Owner’s Manual was no longer printed. The contact checked online and became aware of FMVSS 225, which was related to the Owner’s Manuals for similar vehicles. The contact researched NHTSA Campaign Number: 25V815000 (Equipment), addressing the lack of an Owner’s Manual for 2026 Chevrolet Silverado 1500, 2500, and 3500 vehicles. The manufacturer was not notified of the issue.

In early June 2026 I discovered a sheared pin on the front control arm of my 2026 GMC Sierra 1500 AT4X (VIN [XXX]), sold to me new by Parks GMC, Kernersville NC, with a dealer-installed Performance Package modifying the factory suspension. I delivered the truck to Parks GMC for warranty repair. The dealer represented it as a 1-2 day job. The truck was out of service approximately 2 weeks. The dealer sub-contracted the work to a third-party shop (CCV). At pickup, the dealer provided written documentation stating the repair was NOT PERFORMED. Neither the dealer nor I has been able to obtain any documentation from CCV describing what, if anything, was actually done to the vehicle. THREE UNRESOLVED SAFETY CONDITIONS: SHEARED FRONT CONTROL ARM PIN — original failure, status of repair unknown and undocumented. TIRE-TO-BODYWORK CONTACT — front tires intermittently rub the inside of the wheel wells during normal driving and steering, causing visible damage to the plastic mud guards. Tire-to-bodywork contact creates risk of sidewall failure, sudden air loss, and loss of vehicle control. FRONT RIGHT SUSPENSION CREAK — loud, persistent creak from the front right suspension during low-speed driving and steering inputs. Present at service drop-off, never addressed. Consistent with a worn, loose, or improperly installed suspension component. I escalated to Parks GMC management and GMC Customer Assistance. Parks has not provided a written repair plan, no decision-maker has contacted me, and the only response has been "looking into it." GMC Customer Assistance declined to assign a District Service Manager. I am filing to document these suspension and tire safety conditions in the federal database against this VIN and to request NHTSA evaluation of whether further action is warranted. 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 equipped with Bridgestone Tires, Tire Line: Dueler A/T, Tire Size: 275/60/R20, DOT Number: 17XW09K63. The contact stated that the sidewall around the bead of the four tires were cracked. The tires were dry rotted. The tires were the original equipment. The dealer was notified of the failure in person. The failure mileage was approximately 13,300.

Ac not working properly. Ac blows air to defrost vents foging front windshield and side windows causing bad visibility