2023 GMC Sierra 1500: complete transmission failure

Filed Sep 2, 2026 · Engine, Transmission · PA

I am reporting a serious safety concern involving a 2023 GMC Sierra 1500 Denali, 6.2L L87 V8, VIN [XXX]. This vehicle has now experienced two catastrophic powertrain failures at very low mileage. The first catastrophic engine failure occurred at approximately 23,696 miles. The vehicle was taken to a GMC dealer, where the repair documentation states that the engine had suffered significant internal damage, including damage to the #3 connecting rod, a missing connecting-rod bearing, bearing material throughout the engine, and a scored crankshaft. The dealer determined that the engine was seized and required replacement. GM replaced the engine under warranty with GM engine assembly part number 12740076. The vehicle has now experienced a second catastrophic failure. On [XXX], while traveling approximately 40 mph, experienced grinding, lurching, and knocking, followed by a complete loss of propulsion. The truck would no longer move and had to be towed to a GMC dealer. At the time of the incident, no warning lights or warning messages were observed. The transmission is also suspected to have failed, although the exact cause and extent of the transmission failure have not yet been determined by the dealer. I understand that the federal safety agency is currently investigating failures involving GM 6.2L L87 engines, including failures occurring after previous recall remedies and engine replacements. I am therefore requesting that this incident be included in the federal safety agency’s investigation and considered when evaluating the effectiveness of the existing recall remedy and the safety of replacement L87 engines. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 19, 2026 · Brakes, Transmission · OH

My 2023 GMC Sierra 1500 SLT 4WD currently at 67659 miles was taken in to the dealer because of excessive jerk when accelerating or trying to reverse, diagnostic scan failed for check engine and ABS trouble codes. The scan return code PO747 indicating transmission pressure control solenoid “A” was stuck on for a predetermined period of time. The recommended repair is replacement of automatic transmission, solenoid control valve body. I’m aware that GM has issued a TSB 25–NA-255 and special coverage N24245441–02 addressing this exact failure on the GM 10 speed and that GM previously issued a related recall N242454440 addressing this exact failure on the GM 10 speed transmissions, and that GM previously issued a related recall for this citing rear wheel lock up risk associated with transmission valve condition. My vehicle scan showed an ABS failure at the same time as a transmission. code, consistent with the safety risk. GM has already acknowledged and its own recall documentation however I was told to contact the federal safety agency to document the safety risk and request investigation of the scope of this defect across affected models years and vehicles as mine seems to have fallen short. I previously owned a 2021GMC vehicle same model that experience the identical transmission valve body failure that vehicle could not be repaired in a reasonable time and I ultimately experience financial loss and had to replace a vehicle now I’m experiencing the same defect on the vehicle purchased (this one) with significantly fewer miles than would be expected for a major transmission failure, indicating that this may be a reoccurring manufacturing design defect rather than an isolated incident. Thank you for your time and I hope this issue can be resolved as I do love the truck otherwise however safety first. Thank you

Filed Mar 10, 2026 · Brakes, Driver assistance · SC

This complaint involves a sudden failure of my vehicle’s Anti-Lock Braking System (ABS) and Forward Collision Warning system, both of which are critical safety systems. While driving my [XXX] son to school, multiple warning lights suddenly appeared on the dashboard without any prior indication of a problem. The vehicle displayed a warning message instructing me not to exceed 36 miles per hour, and several system alerts activated simultaneously, my ABS brake system failed and a transmission failure warning. These issues appeared suddenly while the vehicle was in normal operation. Prior to this incident, the vehicle had been functioning perfectly. The evening before, I had driven the vehicle to pick up my son from wrestling practice with no issues. The following morning, during a routine trip to school, these critical safety warnings appeared without warning. Because the warnings involved the braking system, I immediately took the vehicle to Beach Buick GMC for inspection. The dealership diagnosed the issue as a software failure affecting the braking system and informed me that the vehicle required a software update and system download in order to restore proper operation of the brakes and related safety systems. I was required to pay over $300 for this repair because my vehicle is approximately 3,000 miles outside of the warranty period. However, I believe a failure involving the braking system and safety warnings should not occur suddenly in a properly functioning vehicle and should not be treated as a normal maintenance expense. I contacted **General Motors customer service to ask why a failure involving a critical safety system would not be covered or investigated further. The only explanation provided was that the vehicle was outside of the warranty period. I requested a written explanation of their decision for my records, but I was told that providing written explanations is against company policy. I have more to say but I am out of characters... INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMA

Filed Feb 25, 2026 · NY

At approximately 29,000 miles, my 2023 GMC Sierra 1500 experienced a transmission failure. The transmission began slipping, shifting improperly, and operating unpredictably during normal driving conditions. This occurred without warning and well below the expected lifespan of a transmission, indicating a serious defect rather than normal wear or maintenance-related issues. The vehicle became unreliable and unsafe to operate, particularly during acceleration and highway driving, where delayed or improper shifting created a potential safety hazard. I relied on this vehicle for daily transportation and work, and the worsening transmission condition made continued operation unsafe and impractical. I later became aware that transmission failures are a widespread and documented issue affecting this model year GMC Sierra 1500, suggesting a possible manufacturing or design defect. Due to the severity and premature nature of this transmission failure, I was forced to return the vehicle early. General Motors is now charging me a balance of over $10,000 related to the early lease termination, which was directly caused by this defective transmission and not by customer misuse or negligence. My requested resolution is for General Motors to waive the full balance of over $10,000, as this financial obligation resulted solely from a premature transmission failure caused by a defect outside of my control.

Filed Jan 28, 2026 · Engine, Transmission · 57,000 miles · WV

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving uphill, the vehicle unexpectedly lost motive power. There was no warning light illuminated. The vehicle failed to restart and was towed to the dealer, where it was diagnosed, and determined that the engine block had failed and needed to be replaced. The vehicle was repaired. The contact stated that later, while driving at an undisclosed speed, the vehicle failed to shift into gear properly and jerked abnormally. There was no warning light illuminated. The vehicle was returned to the dealer and was diagnosed with transmission failure, requiring the PCM/TCM to be reprogrammed. The vehicle was repaired. The contact stated that while driving at an undisclosed speed, the check engine warning light illuminated, and the vehicle was taken back to the dealer, where it was diagnosed and determined that the fuel injector and coolant pump had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was opened. The approximate failure mileage was 57,000.

Filed Jul 29, 2025 · Transmission · MI

The valve body in the transmission failed at 28,000 miles. My name is attached to an additional same exact vehicle where transmission failed. These transmissions should be recalled due to loss of propulsion. The dealership service lots are full of vehicles with the same failed transmission

Filed Apr 1, 2025 · Transmission · NE

Transmission failure upon acceleration through intersection. Engine high revved went into Low Power Mode. Was lucky to not be rear ended with sudden loss of acceleration. Truck would also not go above 40 safely.

Filed Feb 19, 2025 · Transmission · OH

Transmission Light has been on & off for a month and half. Had it at dealer twice, dealer will not confirm a problem. Truck shifts and bucks between first and second gear. Makes stopping in traffic difficult as truck will surge and jump when down shifting while stopping. Took truck to AAMCO Transmission shop. Confirmed problem, no new transmission units or rebuild parts are available for the GM 8 Speed transmission. AAMCO is replacing unit with a used one. This is a company truck also have a second truck having the same issues with half the miles of this unit. In my opinion GM is aware of the issue in that with both trucks at dealer with same issue, they just send me off with no documentation so as to not have a paper trail. Also no new units available makes me believe that GM can not keep up with warranty replacements.

Filed Jun 12, 2024 · Engine · TX

The transmission failed as I as was turning on to a highway. It seemed like it was rapidly shifting between two gears, but I could not accelerate for several seconds and had to immediately pull over into the ditch to avoid a high speed collision. I took it to the shop the next day. The transmission valve body failed, which appears to be a common issue as I've researched incidents like this online. The part was on backorder. Once it arrived at the dealership, the replacement valve body immediately failed again. Now a 3rd valve body is on backorder with no ETA. I've been without my truck for over a month now with no end in site, and I do not have confidence that a 3rd replacement is going to provide a proper and long lasting fix.

Filed Apr 25, 2024 · Engine, Transmission · 15,000 miles · CA

The contact owns a 2023 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the vehicle started to shake abnormally with the check engine warning light illuminated. The contact stated that after arriving at a parking structure, the transmission warning light illuminated. The vehicle was towed to the local dealer where it was diagnosed with transmission failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 15,000.