2018 GMC SIERRA 1500 Power Train Problems

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.

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.

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...

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.

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.

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.

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.

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.

Transmission shutters when going over 50mph

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.

Transmission shutting and torque converter came apart destroying the transmission.

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

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.

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.

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...

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!

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.

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!

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

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...

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...

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.

The transmission would purge forward when shifting gears. The shifting was very rough. This vehicle had recently been in accident.

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...

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

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.

When I first bought my 2018 GMC Sierra with the 8 speed transmission it would shift hard from first to second gear. Then at around 58,000 miles my truck also started to have a vibration coming through the steering wheel around 45-55 mph. I took it to the dealership and they changed the transmission fluid and did a software update. I am now at 80,000 miles and my truck still shifts hard from first to second gear and makes a grinding sound when accelerating sometimes. I am afraid to drive my any long distances for fear of the transmission malfunctioning. I have not been back to the dealership since my truck is no longer under warranty. So the problem has not been reconfirmed by a dealer or independent service center or inspected by the manufacturer. There have been no warning lamps or messages or other symptoms. I hope that GM...

My starter quit at 81,000 miles. It has always been a bit weak starting, but I have never had a starter go out on a vehicle at 81,000. I have replaced it, and the rebuilt starter is better than what was ever on this vehicle. I am also having problems with the transmission shuddering, shifting rough in low gear, and sometimes it reverses fast. Repair shops won't even touch the transmission. The dealership stated they couldn't get the problem to replicate the issues even though they know there are issues with the 8 speed transmissions.

Transmission malfunctioned while driving, causing no available power to move the vehicle. Had to coast in neutral and stopped in the road. Towed the truck to the dealer and they confirmed the transmission has failed. No warning lamps present or pre-indication of failure.

Vehicle jumps when shifting gears. When coming to a stop it jumps Forward. Hard shifting.

Knocking, stalling, shaking, lost of power and steering problems. Serviced transmission twice and I was advised to serve every 30000 miles!!! I owned several types of vehicles but I never heard such things before. Technician told me that apparently many GMC customers reported same problems.

Electrical system turns off power steering while driving Dashboard lights up like a Christmas tree service track service brake stability Had this service back in 2022 August the problems have resurfaced there are no recalls have spent lots of money and still failing Spent almost a year at the dealership fast forward to years later the same problem is occurring I am running out of money

When accelerating (at times) truck will shudder. Sometimes barely noticeable, sometimes violently. Was told by dealership that torque converter is going out and will be $4000 to replace but may not even fix issue. Looking online, appears that MANY (1,000’s) people are having same issue and that there is even a class action lawsuit about this issue. But no investigation by NHSTA yet, even though I can see many many complaints of similar issues

Shaking when accelerating. Sometimes so extreme it feels like you have been hit by another car. Random, inconsistent, and comes out of nowhere

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the engine temperature rose to 210 degrees and the vehicle started jerking. The contact stated that the failure also occurred while idling for a while, or while stopped at a traffic light while refueling, and before accelerating. The failure occurred once the engine temperature rose to 210 degrees. There were no warning lights illuminated. The vehicle was taken to a certified mechanic at a transmission shop who confirmed there was a failure with the transmission; however, the mechanic was unable to determine the cause of the failure. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was 117,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at 45 MPH, the vehicle began to shudder, and he decreased the speed. The contact drove to his residence. The next day the vehicle was driving as expected until it became hot and began to shudder again. The transmission was not shifting as designed. The contact checked underneath the vehicle but failed to locate an issue with the transmission. The rear differential was hot and burned his fingers, but medical attention was not provided. The vehicle was taken to the local dealer, where it was diagnosed that the torque converter and transmission needed to be replaced. The vehicle was not repaired. The manufacturer was contacted, but no additional assistance was provided. The failure mileage was approximately 22,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated that the vehicle failed to shift into gear as needed. The vehicle was taken to the dealer, where the contact was informed that an unknown part was loose. The vehicle was repaired. Additionally, the contact stated that while driving at various speeds, there was an abnormally loud sound coming from underneath the vehicle near the transmission. The vehicle was taken to the dealer, where the contact was informed that no failure was found. The contact stated that while driving 55 MPH, the vehicle started to decelerate unintentionally. The contact stated that there was smoke coming from the brake pedal. The contact pulled over to the side of the road and allowed the vehicle to cool down however, the brakes locked up unexpectedly. The vehicle was driven to the dealer to be diagnosed. The dealer informed the contact that the...

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving 70 MPH, the vehicle started shaking violently, prompting the contact to pull over to the shoulder of the roadway. The vehicle returned to normal functionality, but upon the contact continuing to drive to his destination, the failure reoccurred. The contact stated that the RPM rapidly increased and the temperature gauge began to indicate that the engine was overheating. No warning lights were illuminated. The vehicle was taken to an independent mechanic, who diagnosed a failure with the auxiliary transmission oil cooler line, resulting in damages to the transmission. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. After investigating the failure, the contact related the failure to Special Coverage Adjustment: N182188930. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure...

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving on various occasions at various speeds, the check engine warning light illuminated, and the vehicle shuddered. Additionally, the drive(D) on the instrument panel started blinking. The contact stated that the engine revved, and the vehicle went into Safe Mode and the vehicle failed to accelerate as intended. The vehicle was pulled over to the side of the road and restarted. The vehicle was taken to an independent mechanic where it was diagnosed and determined that the transmission needed to be replaced. The vehicle was currently being repaired. The manufacturer was notified of the failure. The failure mileage was approximately 40,000.

Engine AFM has failed. No engine light was present at the time. A loud ticking noise was noted from the engine bay. Was taken to get diagnosed, and the AFM was replaced. The problem was then resolved. Transmission has been jerking and hard shifting through the period of owning the vehicle. No diagnosis has been made

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the vehicle was violently shaking. While at a stop, the vehicle slammed the brake pedal, and the steering wheel was shaking. There were no warning lights illuminated. The vehicle was taken to the local dealer, where it was diagnosed that the failure was due to the transmission. The mechanic test drove the vehicle, and the vehicle was shuddering and violently shaking, and the transmission was hard shifting. The vehicle was not repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 42,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated while shifted into reverse, there was a loud clunking sound coming from the vehicle and the vehicle failed to respond as intended. The contact attempted to shift to drive(D) and neutral(N) and then back to reverse(R) however, the failure persisted. The vehicle was towed to a 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. The failure mileage was 92,288.

Drive train:The truck suddenly lurches forward as I'm accelerating and after I've stopped. It's very scary to stop behind a vehicle and suddenly lurch forward. Thankfully, I don't stop too close to another vehicle. The truck also shudders and experiences significant delays in acceleration after coming to a stop and going again. Automatic Emergency Braking: the automatic emergency braking system spontaneously brakes as I'm driving when there is nothing in front of me. Thankfully, nobody has been following behind me when this happens yet. I had to turn the automatic braking system off in order to avoid being hit.

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.

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....

2018 gmc Seirra 1500 8 speed transmission. Making unsafe conditions while driving transmission tends to make hard shifts, jerks, hesitation when moved into gear, gets worse when stopping momentarily at stop lights and then trying to accelerate vehicle will not move. Makes hard shift and jerks then will accelerate in an unsafe manner.

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

Transmission started to shutter at 24000 miles. Dealer said couldn’t find anything. ABS and Stabilitrack light came on at about 40,000 miles off and on. Both these problems could result in a crash. On freeway or streets. The display information/ radio has a mind of its own. Connects to any phone number or start the on star call and etc. it takes your attention off the road and can result in a crash.

The contact owns a 2018 GMC Sierra LD. The contact stated the vehicle experienced jerking and shaking. The contact also stated when the accelerator pedal was applied, the vehicle made a loud noise and lunged. There were no warning lights illuminated. The vehicle was taken to the dealer where a transmission flush and an alignment were performed. However, the contact stated the failure persisted. The manufacturer was notified of the failure and a complaint was filed. The failure mileage was approximately 30,000.

Hard changes with transmission like a car has hit you from behind. It has had a hit in the transmission changing gears since 15,000 miles but it has progressively gotten worse and at 67k it’s enough to knock you to change steering direction.