2018 GMC Sierra 1500 transmission problems

POWER TRAIN

Vehicle Details: 2018 GMC Sierra 1500 Z72 4x4, 5.3L V8 EcoTec3 engine, VIN: [XXX] Mileage at time of incident: 220,000 miles Location: [e.g., Little Rock, Arkansas area or specific road/highway – please provide if desired] What happened: The 5.3L V8 engine’s hydraulic roller lifters failed. One or more lifters collapsed, stuck, or lost proper oil pressure/operation. This led to improper valvetrain function, causing loud ticking/knocking noises, cylinder misfires, significant loss of engine power and performance, and internal engine damage (such as camshaft lobe wear or related components). Component or system that failed or malfunctioned: Hydraulic valve lifters (camshaft followers) in the engine valvetrain, associated with the Active Fuel Management (AFM) system. The failed lifter(s) and related components are available for inspection upon request. How safety was put at risk: The engine malfunction resulted in sudden or progressive power loss and misfiring while driving. This reduced the vehicle’s ability to accelerate or maintain speed, especially in traffic or on highways, creating a hazardous situation that put my safety and the safety of other road users at risk of collision or breakdown. No accident or injuries occurred , or other symptoms prior to the failure with details recall, e.g., ticking noise timeline, misfires Has the problem been reproduced or confirmed by a dealer or independent service center? “Yes, confirmed by shop inspection” Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? [Yes] Additional notes: Repair estimate is approximately $20,000 (likely due to extent of internal damage requiring major engine work or replacement). This failure aligns with a well-documented issue in GM 5.3L engines equipped with AFM. Vehicle status parked INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11743611 — an unverified report by a vehicle owner.

POWER TRAIN

The transmission has always been rough. It has now gone out at 75,000 miles. This transmission issue really seemed to get worse about 50,000 miles. But when I called the dealer, they said they were backed up and couldn't get to it for 9-12 weeks (Covid excuses at that point). Then, it really had an issue going down a large grade into [XXX] . But the issues seemed fairly intermittent. I had an independent shop who said it was hard to tell if it was intermittent. They didn't find metal shavings at the time. ADDITIONALLY, it has also always been a little rough driving. A mechanic looking at it today told me there are no sway bar links at all. This truck has not been modified. This had to have come off the line faulty. Among all the other things. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11738210 — an unverified report by a vehicle owner.

POWER TRAIN

I’ve gone through two transmissions on my 2018 gmc sierra 1500 both times the same issue. The gears are shot, hard shifting. Vehicle is well maintained. Both transmissions one original equipment and second bought at the dealership the truck was bought both only lasted over 80000 miles. Driving the truck loss of power or torque is noticed, then a hard shifting. Checked fluid all was good not seeing metallic shavings. Then the overheating of the transmission, faulty valve replaced with aftermarket bypass and did transmission flush. But each occasion there was an incident I would’ve driving on the interstate and vehicle would lose power and almost hard stop and cause a crash. Then vehicle would only go in reverse both times the transmission gave out. The only warning light that ever came on was a transmission overheating and nothing else. I’m currently in the process of having to get another transmission because of the same issue again. Vehicle was seen by a technician and deemed the transmission was shot again.

NHTSA complaint #11721211 — an unverified report by a vehicle owner.

POWER TRAIN

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.

NHTSA complaint #11719391 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at various speeds, there was an abnormal vibration in the steering wheel. There was no warning light illuminated. The contact stated that the tires were replaced, and the wheels and bearings were inspected by an independent mechanic, but no failure was found. The independent mechanic related the failure to an undisclosed transmission recall; however, the dealer informed the contact that the VIN was not under recall. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 28,000.

NHTSA complaint #11718452 — an unverified report by a vehicle owner.

POWER TRAIN

I OWN A 2018 GMC SIERRA DENALI ULTIMATE, The truck has the 6.2 engine which had the lifter issue as stated with the current situation. At the time, the truck had 37,000 miles when the issues started. I purchased the truck from Andy Mohr with 8806 miles on it in November of 2019. I worked overseas for the DOD so that’s why the miles are low. After I got it fixed, ($4500 dollars at Hare Chevrolet) I experienced the transmission shake while driving home from work with my children in it. The transmission was shaking so bad the whole cab was rocking.That repair was $3,300. Now, the truck has piston slap and rod issues and currently at Hare Chevrolet for service. I was told I need a full rebuild ($12,000 dollars or a new engine $14000 dollars). As a retired Air Force veteran, I didn’t expect issues like this, especially when I baby the truck and it currently has 40,530 miles. I had regular oil changes and service, yet now stuck with a high class truck that has serious issues that seem to be ignored by GM and Andy Mohr GMC. Andy Mohr sold me an extended warranty at time of purchase but I paid for a year and a half that wasn’t usable. If I had that warranty I would be covered now.But besides that, it’s a Denali, I shouldn’t be having a new engine at 40,530 miles. I am happy that there is an investigation but it needs to be widened because my truck was right before the new model rollout but I am having the same issues. If needed, I have all my receipts and information and will provide the service rep at Hare. The reason why its at Hare vs Andy Mohr is due to me catching them not fully servicing my truck and joy riding my Camaro ZL1 after an oil change before I went home for a funeral.

NHTSA complaint #11712288 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle was shaking abnormally. No warning light was illuminated. The vehicle was taken to the dealer to be diagnosed, and it was determined that the engine needed to be replaced. The vehicle was then taken to an independent mechanic, who determined that the torque converter had failed. The torque converter was replaced, but the failure persisted. The vehicle was taken back to the independent mechanic, who replaced the torque converter a second time. The manufacturer was not made aware of the failure. The failure mileage was approximately 140,000.

NHTSA complaint #11711245 — an unverified report by a vehicle owner.

POWER TRAIN

I have 125,000 miles on my truck. I was traveling with my grandkids in the back seat. We were going through a four way stop. My truck started tapping like a lifter issue. The next thing I know is the truck engine light started flashing and car started to shake. Then, my truck lost all power and a big cloud of blue smoke came out of the tail pipe. The truck could not be driven any further. The symptoms: engine tapping, low oil, engine light flashing, shaking, lost all movement, and a cloud of smoke We had to tow my truck to the dealer and they are still accessing the issue. All symptoms are identical to the current recall of the GMC engines.

NHTSA complaint #11705013 — an unverified report by a vehicle owner.

POWER TRAIN

2018 GMC Sierra started having shuddering/jerking/jumping problems at around 60k miles. This problem occurs while driving on straight aways, going uphill and while in drive at a stop sign/light. When the gas is accelerated the truck then hesitates and jerks/jumps. We have taken it to the GMC dealership and paid for the diagnostics and were informed “the problem wasn’t severe enough”. The truck has only been serviced by GMC dealership. So after failed attempts with GMC service department we have taken it to a local small auto shop and they automatically said it was the Drive Train and needed to be taken to a transmission shop. We have been GM owners for decades and are so disappointed in the service received from them.

NHTSA complaint #11700188 — an unverified report by a vehicle owner.

POWER TRAIN:AUTOMATIC TRANSMISSION:TORQUE CONVERTER

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 NHTSA Hotline to report the failure. The failure mileage was approximately 89,000.

NHTSA complaint #11699411 — an unverified report by a vehicle owner.

POWER TRAIN

Repeated transmission issues with the 8 speed transmission due to the malfunctioning valve body. This has caused major safety issues and nearly killed my family with the vehicle locked up and wouldn’t shift on the interstate. The dealership did a warranty repair on the torque converter which made the symptoms slightly better until the vehicle was no longer covered by warranty, at which time all symptoms came back. GM knows their 8 speed transmission has an issue and hasn’t provided a solution. Now, due to the faulty valve body, I have to have my entire transmission replaced for $8000.

NHTSA complaint #11698051 — an unverified report by a vehicle owner.

POWER TRAIN

I purchased a 2018 GMC Sierra 1500 6.2 Denali new. I followed all service requirements including oil changes by GM dealerships. 2025 i noticed my truck power was decreasing. Than I started to hear knocking noses. I took it to a dealership for diagnosis but they couldn't identify anything. Finally it started to skip this is when a dealership diagnose it as being an issue with the active fuel management system. They said my lifters, camshaft, and various other parts was damaged and had to be replaced. Additionally, they said it was a recall on 6.2 engines with the same identical issue but my year wasn't included. The cost to repair approximately 10,000. I really need your attention to this matter! September 10, 2025 my truck placed me and others in danger when it lose engine power. Also my engine light was on for the first time.

NHTSA complaint #11696714 — an unverified report by a vehicle owner.

POWER TRAIN

Transmission shutters when going over 50mph

NHTSA complaint #11683980 — an unverified report by a vehicle owner.

POWER TRAIN

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.

NHTSA complaint #11682446 — an unverified report by a vehicle owner.

POWER TRAIN

Transmission shutting and torque converter came apart destroying the transmission.

NHTSA complaint #11680036 — an unverified report by a vehicle owner.

POWER TRAIN

I have a 6.2 engine that had a number 4 cylinder failure due to a engine defect of the crankshaft. They have recalled the 6.2 motors on the 2021-2024 year models. The 2018 year models with the 6.2 engine should be recalled also bc they are having the same issue. Please help

NHTSA complaint #11676398 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving approximately 70 MPH and attempting the pass another vehicle, the accelerator pedal was depressed; however, the vehicle lost motive power and decelerated unintendedly. The contact pulled over and restarted the vehicle however, the vehicle failed to accelerate above 40 MPH. The vehicle was later taken to the local dealer who diagnosed that the transmission was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was not yet contacted. The failure mileage was 81,000.

NHTSA complaint #11676175 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at 60 MPH, there was an abnormal vibration coming from the steering wheel. No warning light was illuminated. A dealer was contacted. The vehicle was taken to the dealer, where it was diagnosed, and determined that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and transferred the contact to the NHTSA Hotline to report the failure. The approximate failure mileage was 125,326.

NHTSA complaint #11675936 — an unverified report by a vehicle owner.

POWER TRAIN

I own a $35,000 2018 gmc Sierra 1500 6.2l V8 4x4 Denali, which is currently down due to engine failure while I was driving down the road.. never had a check engine light on the dash. Haven't had the truck a year before it quit. Rods knocking, crankshaft bearings, loss of power, high rpm with little acceleration. I could have the peddle down to the floor and would barely get to 20 mph.. the motor would jump so bad, you would think it's going to jump out the truck. I have replaced several parts on the truck, including oil pump, filter, solenoid valve sensor, fuel pump, injectors, and sensors, battery, starter a couple times. Did all that replacing for it to get worse and finally quit while driving.. I was stranded in the middle of the road.. IV reported it to the Recall people, but nothing helped. I have taken my vehicle to Express Chevrolet and they did a diagnostic test, which I provided the list they gave me below. When I took it to them, I was using Endurance Warranty, but they denied my claim due to the issues and they didn't cover them. At the time, the motor was still jumping, but smoke was coming out the tailpipe extremely bad, the truck was jerking and jumping. After replacing everything I listed, the truck got worse, started screeching and knocking loudly, loss of engine power, little acceleration. The day the motor quit on me while driving, I got the mph up to about 55-60 and it just quit, and hasn't started back since.

NHTSA complaint #11674727 — an unverified report by a vehicle owner.

POWER TRAIN

I'm experiencing constant transmission shuddering at constant speed between 25 and 40 mph. This is a know issue, General Motors known issue, with the 8 speed transmission installed in this vehicle. TSB 18-NA-355 was issued in August of 2019 for this issue, but general motors refuses to recall all affected vehicles. Something needs to be done about this!

NHTSA complaint #11671301 — an unverified report by a vehicle owner.

POWER TRAIN

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.

NHTSA complaint #11670689 — an unverified report by a vehicle owner.

POWER TRAIN

Transmission has a shudder at lower speeds 1200 RMP area. Has been doing it since I bought the truck a few years ago. Took it back for warranty work and they claim this is a very common problem with this transmission. Claim that flushing the system would repair it, which it has not. Occasionally to will almost go out of gear, I have to try getting off the road safely to shut it off. After a few minutes, start it up and it will be back to normal. Also I’m on my 3rd starter. What appears to be another common issue with this model. Sometimes it fires right up, sometimes it’s very weak and others not at all and requires a jump start. All in all, recalls should’ve already been applied to these models. Pay way to much for junk!

NHTSA complaint #11669494 — an unverified report by a vehicle owner.

POWER TRAIN

When driving the transmission will shift hard almost jumping forward, especially from a stopped position into 1st.

NHTSA complaint #11667206 — an unverified report by a vehicle owner.

POWER TRAIN

I am the original owner of a 2018 GMC Sierra 1500 with the 6.2L L86 engine and 8-speed 8L90 transmission. I began experiencing severe transmission shuddering and harsh shifting, especially at lower speeds or under light acceleration. When the issue occurs, I press the gas and the engine revs up to 6,000 RPM without reaching 20 MPH, making it extremely difficult — and dangerous — to merge into traffic or cross intersections. This issue has worsened over time and is now a critical safety concern, especially with children in the vehicle. I have researched this issue and found that many owners report the same transmission defect, and there is an open class action lawsuit and a GM Technical Service Bulletin (TSB #18-NA-355) describing the exact symptoms. The vehicle has become unsafe to drive. GMC should issue a recall or mandatory repair program for this known defect before someone is injured or killed.

NHTSA complaint #11665900 — an unverified report by a vehicle owner.

POWER TRAIN

Engine lifters failed. Heard ticking noise first day truck was purchased that gradually got louder but was told by gmc service shop it was normal to hear the ticking noise. Also when cruise control is on and you are decending a hill the rpms raise and you lose engine compression this will cause your speed to drop to around 20 mph and has happened nunerous times.. as well when making a turn sometimes or just driving the vehicle turns off while in motion and you have to coast to the side of the road and turn the key off and back on to start driving agsin.. the loss of power is a complete blackout no dash.. no engine nothing. As result of the lifter issue the engine also hard shifts in and out of slow gears.. I have not driven my truck in about a year and still owe 22k on it. The issues with this vehicle are the same as the recalled 6.3 v8 engines.

NHTSA complaint #11665102 — an unverified report by a vehicle owner.

POWER TRAIN

GM has discontinued a critical engine belt on the 2018 GMC Sierra 1500 5.3L eAssist. This makes the truck undrivable and unsafe to own, even though the vehicle is still under financing and only 7 years old. There is no available part, and no alternative has been offered by the manufacturer.

NHTSA complaint #11660821 — an unverified report by a vehicle owner.

POWER TRAIN

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

NHTSA complaint #11657672 — an unverified report by a vehicle owner.

POWER TRAIN

Transmission just would not go them all of a sudden it jersey really hard in second gear an start to pick up speed..cold starts it change gear really hard in second gearc often times slipping then going into gear really violently.. need fix asap dealer has service once with the issue, change fluid an stopped a while ago now issue is back an worst then before.. 44,785 vehicle should not operate this way.4×4 awd trans starts at 6500 to replace an go up to about 13200 to replace

NHTSA complaint #11656466 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2018 GMC Sierra 1500. The contact stated that while attempting to accelerate from a stop, the vehicle failed to accelerate while depressing the accelerator pedal. No warning light was illuminated. The vehicle was taken to a local dealer, and the transmission was repaired under warranty. The contact stated that a year after the repair was completed, the failure reoccurred. The vehicle was not repaired after the most recent failure. The manufacturer was made aware of the failure. The failure mileage was approximately 94,600.

NHTSA complaint #11649082 — an unverified report by a vehicle owner.