2018 GMC Sierra 1500: complete transmission failure

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 Sep 6, 2026 · Engine, Transmission · KY

I own a 2018 GMC Sierra 1500 V8 5.3 liter which is at 46, 433 miles. Over the past few weeks I have noticed the transmission having difficulty shifting in first gear and lurching, and making shuddering noises, and as well making a constant ticking noise. After an experienced mechanic had put a diagnostic system onto my truck, his system diagnosed a Transmission Lifter Failure, specifically 2 out of the 8 lifters. A few days later (9-04-26) I took my truck to a certified GMC servicing business (Patriot Chevrolet of Hopkinsville KY 270‑886‑1207) and had a transmission servicing done. I had told the Customer Service representative Amanda Williams about the ticking and that I thought 2 lifters going bad in the transmission were the source of it. 3 hours later the servicing was done which cost $ 474.43. She did not know if the ticking had stopped or not. I started my engine to head home and the ticking was still happening. Nothing had changed. I got home, parked and have not started the engine since to minimize any further damage. I have become aware that this year, make and model has become infamous for the engine/transmission design and parts failure which has been at the center of thousands of class action lawsuits. I have owned this vehicle since inheriting it from my late father for 2 months before he developed dementia and suffered a broken hip. I have religiously had the oil changed every three months regardless of the mileage, and this is a sealed transmission which cannot be worked on by someone but a certified GMC mechanic, which wasn't a worry because the truck's manual says doesn't need to be worked on unless there seem to be problems. Which is what I did on 9-4-26, hoping that a servicing would fix the issue. During the 5 years that I have owned this truck, I never received ANY sort of notice from GMC that might've hinted at possible Transmission Failures, though GMC has been totally aware of. Sudden power loss dangerous and unfairly expensive to drivers.

Filed Feb 20, 2026 · Transmission · 130,000 miles · LA

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked abnormally hard. No warning lights were illuminated. The vehicle was taken to the dealer, where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was repaired; however, the failure reoccurred. The vehicle was taken to the dealer, where it was diagnosed and determined that the transmission was failing. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The contact was informed that the repair was not covered under warranty. The transmission was replaced two years ago. In addition, the contact stated that the original transmission had failed at 130,000 miles. The manufacturer was not made aware of the failure. The failure mileage of the second transmission was approximately 40,000.

Filed Nov 14, 2025 · Transmission · 89,000 miles · AL

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission vibrated. No warning lights were illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed with a failing torque converter. The contact was informed that the torque converter needed to be replaced. The vehicle was not repaired. In addition, the contact was informed of a Manufacturer's warranty. The contact was informed of a Manufacturer's warranty for the 2018 GMC vehicle's transmission failure due to the incorrect oil being used during production of the torque converter. The dealer was made aware of the failure; however, the contact was informed that the manufacturer needed to approve the repair coverage. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the federal safety agency Hotline to report the failure. The failure mileage was approximately 89,000.

Filed Aug 22, 2025 · Transmission · 101,000 miles · GA

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed toward the residence, the accelerator pedal was depressed and traveled to the floorboard, and the vehicle failed to drive forward as intended. The vehicle started rolling backwards and the contact carefully maneuvered the vehicle while attempting to park. There was no warning light illuminated. The vehicle was towed to the dealer and diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 101,000.

Filed Jul 2, 2025 · Engine, Transmission · TN

This 2018 GMC Sierra has 100,000 miles on it and in April 2025 the transmission went out and needed a new one. Now in July 2025 the engine has lifter failure leading to the need of a new engine.

Filed Apr 29, 2025 · Engine, Transmission · CA

I have taken it in due to engine mounts 4 different times, transmission replaced and in October 2024 I took it in for issues I was experiencing like I had before my transmission went out. I did not get my truck back until almost Dec 2024 and that was due to there employee backing into the front end of my truck. So after all that my warranty was up Dec 24 2024 and then on April 16th 2025 I was driving my 2018 GMC Sierra 6.2l 1500 Denali 129,600 miles at approx 30 mph it was late so the streets were empty and we started to hear a knocking or what I thought at the time was a very bad exhaust leak. We parked and then we started to try to make it home very slowly which we did and it was not making to much noise. The next day I called GMC and explained they said bring it in. I towed it there to be safe but it did start and still ran at very slow speed. They called me and said that the lift side rockers/ lifters 1 failed and it was stuck due to a misfire and that the engine would need to be rebuilt and sent me over some very vague break down which looked like a lump sum price. I requested and better break down and got a screen shoot and that when he said that’s the best they can do. There were no engine lights on or warnings nothing at all. It also just got serviced at GMC for an oil change on February 27th 2025 along with some air filters. Today is April 29th and still waiting for the service manage to call and see if they can do anything to help out instead of charging full price. I will Attach pictures of the cost break down if possible. Thank you

Filed Jun 28, 2024 · Transmission · AR

The contact owns a 2018 GMC Sierra 1500. The contact stated that while stationary at a stop light and attempting to depress the accelerator pedal, the vehicle hesitated while responding. The check engine warning light was illuminated. The vehicle was taken to an independent mechanic where the vehicle was diagnosed with transmission failure. The contact stated that several unknown parts were replaced. The manufacturer was not made aware of the failure. The failure mileage was unknown. The VIN was not available.

Filed Jun 25, 2024 · Transmission · NV

We purchased our 2018 GMC Sierra 1500 z71 brand new at Fairway Buick GMC in Las Vegas, NV. Pretty much off the lot we noticed some hard shifting, but over the last year/around 60,000 miles it has become progressively worse. Come to find out GM is aware of a known defect in the transmission used in this make/model and several others by GM which causes hard shifting and jerking while upshifting and down shifting primarily between 1st and 2nd gear. This malfunction has caused the vehicle to activate "limp mode" which doesn't allow the vehicle to move out of 1st gear, while driving on the road, putting the safety of the occupants and others on the road at risk. This first happened in January 2024 while we were moving and towing a 6' U-Haul trailer. Luckily we were within a few miles of our destination and made it there safely. Upon taking it to Autonation Buick GMC, we were told they had seen this issue before and the only solution would be to replace the transmission and would cost roughly $6,000-$8,000, and that's with the generous 20% discount they were willing to offer. We opted to have the transmission flushed instead and it seemed to fix the problem temporarily. Then on [XXX] while decelerating and coming to a stop light it hard shifted from 2nd to 1st then the check engine light came on and limp mode was activated. It was 110 degrees on this day in Las Vegas when my husband was driving home from work, and again by the grace of God, he was only 5 minutes from home and made it there safely. However, what if this had occurred with our two young children in the vehicle and we were no where near home? We would have been stranded in dangerous conditions potentially putting our safety as risk. This KNOWN defect in GM transmissions is 100% a safety risk and this needs to be investigated and recalled immediately. There is an ongoing class action lawsuit against GM regarding this issue and I will be looking to get involved as well. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(

Filed Apr 30, 2024 · Suspension · 93,555 miles · KS

The contact owns a 2018 GMC Sierra 1500. The contact stated that while the vehicle was at an independent mechanic for an oil change, the independent mechanic performed a full inspection of the vehicle. The contact was informed that the CV axles were corroded, and the CV axles needed to be replaced. The vehicle was repaired. The contact was advised to report the failure to the dealer. The contact informed the dealer of the failure. The contact stated that the vehicle had been taken back to the dealer several times for repairs, including the transmission replacement, radiator replacement, and a full suspension replacement. The manufacturer was made aware of the failure. The failure mileage was approximately 93,555.

Filed Apr 25, 2024 · Transmission · MO

My 2018 gmc 1500 transmission making noise grinding. It only has 75799 Miles on it. I just was told by Laura gmc that my transmission needs replacing. I think gm should cover that. Dealer charging 7800.00 to replace it. That's not right the truck doesn't have that many miles on it. Please help

Filed Mar 3, 2024 · Transmission · WA

At 66,963 miles my transmission failed while driving. The check engine light came on and the car would not shift out of first gear. The car was towed into Gilchrist GMC in Tacoma WA. and I was informed I needed a transmission replacement, cost of $7552.24. Come to find out there is a class action lawsuit currently filed for GM owners of this transmission, claiming some 800,000 GM products contain a knowingly faulty transmission. A recall should be in place being that nearly a million vehicles are affected by this.