2017 GMC Sierra 1500 transmission problems

Filed Nov 2, 2026 · Transmission · LA

I am submitting this complaint to bring attention to a potential widespread engine defect involving GM's 6.2L engines, specifically the use of replacement crankshaft Part Number 12732518 in engines that were not originally equipped with the L87 engine. Approximately one year ago, I completed a second engine replacement on my 2017 GMC Sierra equipped with the 6.2L L86 engine. My original rebuilt engine failed after GM supplied a replacement crankshaft that was determined to be out of specification. Following that failure, I had to go through the expense and labor of rebuilding the engine a second time. The concern is that GM discontinued the original L86 crankshaft, Part Number 12623492, and supplied Part Number 12732518 as its replacement. My understanding is that Part Number 12732518 is also used in the L87 6.2L engines that are currently experiencing widespread engine failures and have drawn the federal safety agency's attention. After installing the replacement crankshaft, my L86 engine experienced a failure consistent with the failures being reported in L87-equipped vehicles. This raises a serious concern that the replacement crankshaft may share the same underlying defect or contribute to the same failure mechanism affecting the L87 engines. I am resubmitting this complaint in light of the federal safety agency's recent efforts to obtain additional information from General Motors regarding the 6.2L engine failures. I believe this information is important to the investigation because the potential defect may not be limited to vehicles originally manufactured with the L87 engine. I strongly urge the federal safety agency to investigate whether GM's replacement crankshaft, Part Number 12732518, creates the same engine failure risk when installed in L86 engines. Any investigation, recall, or corrective action should consider not only vehicles originally equipped with the L87 engine but also vehicles that received replacement engines or replacement crankshafts Part Number 12732518.

Filed Sep 18, 2026 · Transmission · 140,000 miles · MS

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving approximately 30 MPH to 50 MPH, the vehicle shuddered and made a shuddering sound while shifting between gears. Additionally, the contact stated that the engine lifters and camshaft were previously replaced. The contact associated the failure with the federal safety agency Campaign Number: 25V274000 (Engine and Engine Cooling); however, the VIN was not included in the recall. The traction control warning light was intermittently illuminated. The manufacturer was notified of the failure by phone and informed the contact that the VIN was not included in the recall. The contact was referred to a dealer to determine whether the failures were associated with a recall for coverage consideration. The contact stated that a coworker's vehicle experienced an identical transmission failure, and a transmission specialist diagnosed that issue as a torque converter failure. The failure mileage was approximately 140,000.

Filed Sep 11, 2026 · Engine, Transmission · OR

The catastrophic power failure with no warning on my 2017 GMC Sierra, at 87450 miles completely contaminated the engine oil cooling lines with metallic debris and fractured structural mounts. The servicing dealership replaced the transmission but is refusing to remediate the engine line contamination without out-of pocket payment. The vehicle cannot be safely operated without causing terminal engine failure on the highway, creating a imminent mechanical and traffic safety hazard.

Filed Feb 4, 2026 · Engine, Transmission · VT

check engine light and traction control light on. vehicle undriveable. took to dealer code P0304 lifters need to be replaced

Filed Jan 25, 2026 · Transmission · NV

My vehicle has lurched forward upon the first engine start of the day, under no throttle, on several occasions, throughout the life of my vehicle. Shortly after starting my 6.2 engine in my garage, if I shift my 8L90 transmission into Drive as soon as the engine RPMs settle to idle, the vehicle will lurch forward, screeching the tires. Luckily, I had my foot on the brake hard enough such that no one was injured. The harsh transmission shift into drive is dangerous, possible injuring passengers or my garage door. I've learned that if I wait 5 to 10 seconds, allowing the engine to idle (while the transmission oil becomes pressurized ??), then the shift into drive is normal, without any lurch.

Filed Jan 25, 2026 · Transmission · NV

After 38,000 miles and 8 years of normal service (mix of city, highway, and 10% towing), my 8L90 transmission began to shudder occasionally. The problem first became apparent when driving slightly uphill, on cruise control at about 50 mph, or while slightly accelerating on a flat road, with no load in the box, and no trailer. It felt like I was driving across a rough patch of asphalt or rumble strips. Every half mile or so, it would shudder. Slowing down or speeding up stopped the rumble. The problem proved not to be caused by tires, U-joints, or AFM. The problem in fact was caused by defective GM transmission fluid, which was sold as "sealed for life", and rated for 200,000 miles, as factory-installed. That proved to be BS. If not repaired, this problem would lead to transmission lockup and/or lack of propulsion, which could contribute to a vehicle crash. The problem was solved by installing AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid, Product Code: ATLTP-CA. If GM properly cared for their customers, to make up for false advertising at the time of purchase, GM should publish and pay for GM Service Bulletin #20-NA-142, for all 8L90 owners, instructing owners to replace their transmission fluid every 5 years or 40,000 miles, whichever comes first.

Filed Dec 30, 2025 · Engine, Transmission · 80,000 miles · MD

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked and slammed into the intended gear. The check engine warning light illuminated. The contact stated that the failure had persisted, and the vehicle had failed to accelerate as intended while depressing the accelerator pedal. The contact stated that the drive was rough, and there was an abnormal rumbling sound coming from the engine. The contact stated that the engine misfired. The vehicle was taken to several unknown locations for diagnostic tests, and it was confirmed that the transmission and the engine had failed. The contact was informed that metal shavings were found in the transmission fluid. The vehicle was not repaired due to the cost. Â The contact was provided with the manufacturer's TSB Number: 20-NA-138; however, the vehicle was not covered. The manufacturer was notified of the failure; however, the manufacturer was unable to locate the Warranty Administration Service Bulletin. The manufacturer referred the contact to the federal safety agency Hotline for assistance. The failure mileage was approximately 80,000.

Filed Dec 3, 2025 · Transmission · WI

Transmission Hard shifts 1-2 or 2-3 Delayed engagement into Drive/Reverse Shudder at 30–60 mph Slipping under light throttle Clunk when stopping The risk I've described to the dealer is that the hard shifts at stop and go in heavy traffic situations could cause and accident. Yes the issue has been confirmed at the dealer and they replaced the transmission. That did not resolve the issue. It has not been inspected. No warnings.

Filed Oct 29, 2025 · Transmission · 128,177 miles · NC

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. No warning lights were illuminated. Additionally, the RPM increased quickly. The contact stated that the failure occurred while driving on a busy highway. The contact drove the vehicle across a four-lane highway to get the vehicle to the shoulder of the road. The contact stated that the transmission had seized. The vehicle was towed to an independent mechanic, where the vehicle was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was repaired. The manufacturer was made aware of the failure but provided no assistance. The contact referenced an unknown recall with a similar failure description; however, the VIN was not included. The failure mileage was approximately 128,177.

Filed Oct 17, 2025 · Electrical, Steering · IA

Driving in town going 20mph and the truck shut down not allowing for braking or gas and the steering locked up. Placed the vehicle in neutral, shut the truck off and turned it back. Was able to continue driving. Attempted to have the dealership we bought it from run a diagnostic and the battery was replaced but it continues to shut down at random times. Took the truck to a local auto shop after this happened again, another diagnostic was run, I am waiting the report to confirm what was done.