GMC Sierra 1500 transmission failure problems

Filed Nov 3, 2026 · Brakes, Electrical · OK

While the truck was under warranty it would go into limp mode. A dealer said they replaced the valve body but it did not look like anything had been done to it. It didn’t go into limp mode and seemed fine for a couple of months then it went into limp mode again and we took it back to the dealership. The hooked a scanner up and cleared the codes and it worked fine for a couple of more months. (This cycle happened repeatedly until it was out of the warranty.) We finally got our own scanner and cleared the codes like they did at the dealer and it would work fine for a while. Then one day driving at 60-65 mph it locked the rear wheels and we slid off into the ditch. It happened 4 more times before we got it home. (We were driving about 15 mph). We called the dealership and they said they couldn’t do anything since it was out of warranty and it could need a new transmission. It was never right from the time we bought it. The locking brakes could be fatal if it had happened on a busy highway. The first problem we had with it was the front grill flew off. We called the same dealer and they told us we pushed too hard on it closing the hood so they weren’t responsible. My husband fixed it and it never came off again but we saw later that it had been recalled for the same problem.

Filed Nov 1, 2026 · Transmission · NH

Loss of power, shuddering, hesitation upon attempt to accelerate. 8-speed automatic transmission failure, known to GMC at the time of purchase (2017). GM Service Bulletin 39370 dated April 2016.

Filed Nov 1, 2026 · Engine, Transmission · FL

At three years old with 37,000 miles on it, the engine started ticking loudly consuming oil when I went to look it up. I saw there was a recall. Nobody had notified me about the recall. The technician said it failed their diagnostic test and I would be getting a new engine. Nine weeks later, I get a new engine. One year later at 51,000 miles the transmission failed.

Filed Oct 18, 2026 · Fuel system, Transmission · TX

This report shows 4 more new attempts to repair the drop in power, bucking, surging, and lurching that my truck has been doing since May 2026, after the L87 Engine replacement. This issue has caused me to come very close to rear ending a few vehicles, including a Deer Park police officer. It has caused me to run through red lights unexpectedly. The vehicle has had a case open with GM Corp. Customer Care, Case(s) 95259917 (OLD), Case # 108994166 current case (Phone, Instagram). The problems are dangerous because the truck can begin shutting down and feel as if its stopping due to being stuck between gears or maybe torque converter. It happens on the highway at different speeds. It happens in city, stop and go traffic. The lunging forward comes into play with no prior warning. No lights, no messages on the instrument cluster. The dealer had me come in and drive the vehicle to show one of the managers what is happening while I am commuting. It has been confirmed EVERYTIME I was told there is no problem. I am attaching the latest work orders related to the issues after the engine replacement. For the past 6 months this truck is in the shop or stuck in my driveway more than it is driven or used. It is medically necessary that I have transportation available 24/7. I am under the care of several specialists since I was diagnosed and treatment for cancer began. Notice there are TWO work orders NUMBERED "63481" They are attached. ONE the third attempt dated (8-28-26) printed when i picked it up my ADAS was replaced and it has AVISRentCar, I paid for. Second "63481" forth attempt dated (9-15-26) printed when i picked it up after a Transmission relearn AGAIN (duplicate W.O. #) This one has Enterprise Rental I paid for. Now a FIFTH attempt to repair the same issue (9/21-9/29) This time they replaced the transmission valve body. Now, the truck is in the shop AGAIN, a Sixth time for the same problem. No issues found. I tested it again to show them. I am also attaching FTC report

Filed Oct 10, 2026 · Engine, Transmission · CA

Transmission was replaced about 13 months or so after purchasing and was already out of warranty.

Filed Oct 9, 2026 · Transmission · WA

My 2018 GMC Sierra 1500 experienced significant transmission problems that began as rough, inconsistent shifting, hesitation, and abnormal transmission behavior before eventually progressing to complete transmission failure. These symptoms were present before the transmission's ultimate failure and while the vehicle was still within its warranty period. Unfortunately, during the COVID-19 pandemic, local dealership service departments faced significant staffing shortages and appointment backlogs, making timely diagnosis and repair extremely difficult. By the time the transmission failed completely, the vehicle had exceeded the warranty's 84-month time limitation but remained substantially below its mileage limitation. Despite the relatively low mileage, the earlier symptoms, and the extraordinary circumstances affecting service availability, General Motors declined to provide warranty or goodwill assistance. I was forced to bear the substantial financial burden of a major transmission failure in a vehicle that had not reached the mileage threshold established under its warranty. I believe this failure warrants investigation because transmission problems involving GM trucks and SUVs from this period have been widely reported by other owners. I am particularly concerned about whether GM was aware of recurring transmission defects, whether affected owners received adequate notification, and whether these failures present a potential safety risk through unexpected loss of propulsion, hesitation, or unpredictable shifting. I request that the federal safety agency review this complaint alongside similar reports involving 2018 GMC Sierra transmissions to determine whether a recurring defect exists and whether further investigation or corrective action is warranted.

Filed Oct 8, 2026 · Transmission · NJ

Transmission failed at about 40 MPH, coasted to the side of the road and wheels locked up. No warning lights even after the failure. GM dealership inspected and confirmed it is the common valve body failure on GM trucks but my truck is not covered on recall. It is sitting at dealer waiting for a decision. No warning, the dealer changed the transmission fluid and filter 4000 miles before.

Filed Sep 28, 2026 · Acceleration, Transmission · MS

The vehicle in questions was purchased with less than 5 miles in year 2020. This vehicle was dropped off at MAC HAIK CHEVOLET MADISON MS on September 25, 2026. I was advised on September 28, 2026, that the vehicle was test driven with the scan tool connected, Graph Torque converter slip, found over 100 RPM slip when torque converter engaged and causing shutter at highway speeds, also felt 1-2 and 2-1 harsh downshift, check fluid condition was black and smelled burnt, replace transmission assembly, flush cooler, program transmission control module and perform clutch fast learn. Estimated cost of $8k

Filed Sep 24, 2026 · Transmission · CA

I own a 2021 GMC Sierra 1500 AT4 with the 3.0L Duramax diesel. The vehicle developed severe transmission problems, including harsh/jerky shifting and a hard clunk when shifting into reverse. The vehicle was subsequently diagnosed with an internal transmission failure. The repair facility informed me that the transmission gears had failed and caused damage to the transmission and stated that the failure appeared to be related to a manufacturing issue. The repair facility also advised me to watch for a future recall because they believed this could be a widespread issue occurring in other vehicles. I am submitting this complaint so the failure can be documented and considered along with other reports of transmission failures involving this vehicle.NOTE FROM AUTOSHOP:TRANSMISSION FAILURE WAS DUE TO A MANUFACTURE DESIGN FLAW, NOT DUE TO THE CUSTOMER'S DRIVING HABITS. THE PUMP ORIGINAL DESIGN IS WITH SLANTED GEARS AND THE GEARS ARE FORCED AWAY FROM EACH OTHER AND PLACING TOO MUCH STRAIN THE BEARINGS ANI THE BEARING FAIL. AN UPDATE PERFORMED TO HAVE STRAIGHT CUT PUMP GEARS TO AVOID BEARING DAMAGE. CDF DRUM AND CENTER SUPPORT CHANGED TO UPDATED PARTS THAT ARE HEATED TREATED TO AVOID DAMAGE

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.