Transmission temperature sensor has failed. It is available for internal inspection within the transmission pan. Safety has not been in issue, but, apparently it can cause hard shifting when the sensor starts to go bad. You can also easily tell when the sensor is going bad by watching your trans fluid temp needle. It will erratically bounce up and down, sometimes slightly and other times it's big jumps, so you will not be able to tell if the transmission is overheating or running at normal operating temperature. The problem has been confirmed by a local service center. The vehicle/component has not been inspected. There has not been any problems prior to this issue. The check engine light came on 1/24/24 in the evening time. Check engine codes are P0711 & P0700. This is a known issue between 2015-2018 GM vehicle equipped with the 6.2L & 8-speed transmission. There is/was a special warranty number, #N192291660, that qualifies with the 2016 models.

- Saint Augustine, FL, USA

I was driving my truck home from work, when all the sudden the car at a stop sign lurch forward, with the brake applied and was not moving, or I would have hit the car in front of me. Upon, the green light, truck started to shift and go faster, while making a whining noise, at only 26 miles per hour, then, the vehicle, tried to speed up with nothing engaging, and came to a complete stop very aggressively and abruptly, while in traffic, I almost was hit from the sudden stop. Getting to the side of the road, the truck wouldn-??t move anymore, and except in rear gear. Called OnStar service and vehicle was towed to the closest GM dealership, about a mile from my house. This was on a Saturday evening, On Monday, the dealer service agent called me, had already diagnosed the problem as a failed 6L80 GM transmission, this was at 930am, asked if I wanted it repaired I said yes. The dealer called back at 3pm that same day and said the transmission had already been repaired. Which to me is a bit surprising as it needed a new transmission, which should take longer. Glad it was fixed so fast. The cost was to be around 6700 dollars. From my knowledge this is a known issue with these transmissions. My concern, is that I could have been in an accident from a known defect in manufacturing that GM knew about and did nothing to address.

- Butler, PA, USA

Transmission has stalled many times from shifting through 1st and 2nd gear going across divided highways and nearly causing accidents, also it has a very bad shudder and hard shifting.

- Cocoa , FL, USA

My transmission started to shutter then went in and out of gear till it doesn't stay in gear

- Gansevoort , NY, USA

My 2017 GMC Sierra 1500 Denali started shaking violently and the rpm gage began bouncing 1/4 to 1/2 inch in a very short amount of time. I ran a maintenance facility in Europe with 317 local national and 25 U.S. employees. Two of my brother-in-laws, and one of my nephews are mechanics. Two run their own auto repair facilities. All three reported having to replace torque converters on multiple gmc/chevrolet 1500 trucks. Many at somewhere between 40 and 60 thousand miles. If this is such a systematic problem, and from tghe number of vehicles they have had to repair it is, why hasn't a recall been issued. Second, in most cases dealerships first charge excessively for replacing the transmission fluid (approximately $900) and then end up replacing the torque converter. The owner has to pay for the transfluid replacement out of pocket because it is condsidered maintenance instead of replacing the torque converter at company expense...especially if you purchased and extended warranty through a third party. If this is recalled, owners should be reimbursed if they had to pay for it themselves and they should be required to replace the transmission fluid filter as a part of the repair,

- Murfreesboro, TN, USA

After 80K miles on a 2017 GMC Sierra - my 6 Speed AT Transmission HMD 6L-80 failed. There appears to be know flaws in the GMC transmission, but no recall for my model and year.

- Aptos, CA, USA

The contact-??s husband owns a 2017 GMC Sierra 1500. The contact stated that while her husband was driving at approximately 55 MPH, the vehicle hesitated and stalled. The check engine warning light was illuminated. The contact-??s husband was able to restart the vehicle. The vehicle was taken to the dealer where it was diagnosed that the transmission had failed and needed to be replaced. The vehicle was repaired; however, approximately 1 year later the failure recurred. The contact stated that while her husband was driving approximately 55 MPH, the vehicle hesitated and stalled. An unknown warning light and the check engine warning light illuminated. The vehicle was towed to the dealer where it was diagnosed that the transmission had failed and needed to be replaced. The vehicle was repaired; however, the failure recurred. The contact stated that while driving approximately 45 MPH, the vehicle hesitated and stalled. The vehicle was restarted but the vehicle decelerated while the accelerator pedal was depressed. Additionally, the contact stated that she was informed by the dealer that the vehicle failed to shift into the intended gear and as a result, the transmission failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 100,000.

- Shenandoah Junction, WV, USA

Truck all a sudden developed a Lifter noise under the hood and the check engine light came on Friday, September 8th. I checked the oil and oil pressure which was ok. Saturday morning 9/9 I notice some loss of power pulling out on Highway. I took the truck immediately to a friend who is a retired GM Master Mechanic. He coded P0300 and P0306 with 158 miss fires. The following Monday on September 11th I took the truck to Clift GMC in Adrian, MI. They confirmed a Lifter failure and bent Push Rod on Cylinder six. on my 5.3L engine. Since I have learned the AFM System on these engines is driving Lifter Failures. I was lucky my Camshaft was not harmed. My truck had 84,945 miles on it and is six years old. GM offered no, zero assistance. The Dealer could only state this is a well known issue which they see frequently offer a extended Power Train Warranty at a cost of $1600 t $2000 dollars. How is a Extended Warranty a solution to a poor Engine Design? Help!

- Brooklyn, MI, USA

Transmission issues! Very hard shifting! Feels like someone ran into me from behind. Shutters while crushing at 45-48 mph. Vehicle shakes from transmission issues!! GMC will not do anything about it!

- Bush, LA, USA

Transmission slipping in and out of gear. Transmission was serviced 5,000 miles previous to this for the 100,000 mile service at 95,000 miles. No issues were found at the time of service, now truck will slip out of gear on highways without warning. Transmission fluid is not dirty or burnt. Common reported issue according to online discussions and GMC needs to recall this model transmission

- Mount Lookout, WV, USA

Like so many others, I have persistent transmission or drive train problems in my 2017 GMC Sierra. This has been documented on multiple visits and test drives with the dealer where I purchased the vehicle and to another GMC dealer. The first occurrence was after about 4,000 miles. A loud clunk sound occasionally occurs while shifting thru low gears and the transmission shifts very hard. To the point that the transmission hesitates between gears and then jerks me back into the seat. The selling dealer has witnessed this and tried various repairs (supposedly flushed and replaced the fluid, supposedly replaced an unknown computer component, etc). None of this helped. Now the transmission also hesitates and seems to slip during a downshift thru the low gears. The selling dealer finally told me "nothing is wrong with this truck, so don't bring it back again". I assured them that I would never be back, especially when I'm in the market for a new truck. GM should take note of this, also. Online websites show many posts of owners having this issue. And neither the dealers nor GM are even acknowledging a problem, let alone offering a solution. Unfortunately for me and many others, the value of this vehicle is impacted by so many complaints, no action by NHTSA and questionable practices by GM and their dealers. Buyers beware!!! The transmission in this truck is junk and you won't receive any assistance from GM or its dealers. The only hope for owners of this truck is for NHTSA to step up, launch an investigation and require a recall. This a known issue to owners of this truck, GM, its dealers and the NHTSA. It's time for all of them to step up and do what's right for consumers.

- Las Vegas, NV, USA

I have persistent transmission problems documented on multiple dealer visits where I purchased the vehicle. The first one was after 6000 miles. A large clunk sound and vibration occurred after shifting gears in the 30 mph range. The dealer told me this was a know issue related to the transmission manufacturer lubricant conflicting with the GMC transmission fluid. They did a flush and replace and for a time period it settled down. I have 56,000 miles now and the latest complaint I made was when nearing a stop at 5-10 mph the transmission did a massive clink. I had two others in the vehicle that observed this over 20 times. I immediately scheduled a service to look at this. After 4 hours they told me nothing is wrong. Since then the transmission has a light clunk shifting at low speed so I wonder if they lied and flushed the fluid. They said no metal was in the fluid. Online websites show many posts of owners hanging this issue. I was never shown a bulletin on any reported issues and would like to see every one related to the 8 speed transmission. My standard powertain warranty has expired after 5 years. I fear the value of this vehicle is impacted by so many complaint, no action by NTSB, and questionable practices by two GM dealers that serviced my vehicle. I would like to see a recall as this isn-??t just my issue. I would like to see what investigation NTSB has done on this topic. I have printed service re odds for each I have complained about the transmission and now believe the dealer was aware of the issue and GM bulletins coached them how to tell me there is no issue. The last statement made was also odd, the service advisor told me that the clink is because the transmission sometimes goes from 3rd to 1st and skips second gear. I was charged to have them look for a problem and if this a known issue to both GM and the NTSB shame on you both.

- Clearwater, FL, USA

Transmission needed to be replace after only 73,277 miles.

- Portland, CT, USA

Transmission engine light on, code P0700, P182E. Truck went into limp mode, would recognize what gear its in. Had to shut down vehicle for 10 minutes, restarted then it aloud me to drive.

- Phoenix, AZ, USA

The contact's son owns a 2017 GMC Sierra 1500. The contact stated that while her son was driving 30-35 MPH, he heard an abnormal sound. There was no warning light illuminated. The contact's son veered to the side of the road and attentively listened for the sound. The contact's son then inspected the transmission reservoir and noticed that the transmission fluid had leaked out. The contact-€™s relative brought transmission fluid which was added to the transmission reservoir. The contact's son continued driving; however, the vehicle became undrivable later that day. There was no further information provided. The vehicle was towed to the son-€™s residence. The dealer and the manufacturer were not notified of the failure. The vehicle was not diagnosed or repaired. The failure mileage was unknown.

- Savannah, GA, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving approximately 40 MPH, a grinding noise was present coming from the engine compartment. The contact stated that the vehicle inadvertently decelerated and stalled without warning. The vehicle was towed to the residence and examined by a mechanic, who determined that the transmission had failed. The cause of the transmission failure was not yet determined, and the vehicle was not yet repaired. The manufacturer and local dealer were not notified of the failure. The failure mileage 100,000.

- Savannah, GA, USA

As I am driving the truck I notice that as the accelerator is pressed the truck does not respond as it should. I have taken this to a service repair shop and they have stated it is a ongoing issue with these vehicles. So I have taken it upon myself to look online and sure enough OTHERS have also states the same things.

- Tuscaloosa, AL, USA

Truck has 67,000 miles and has been in the dealer 3 times for transmission issues. First was the shutter. Then harsh jerking downshifts. They flushed transmission and filled with new fluid under warranty and after 1,000 miles light on again for transmission fluid temperature sensor. And now they want $800 to replace this issue. There was a recall on the 16 model for the same issue with the wiring. About to cut loss and file lemon law. Had the truck for less then 2 years and put 15,000 miles on

- Jacksonville, NC, USA

My vehicle shakes at different speeds. Do to the admitted mistake that GM said certain assembly lines put the wrong Transmission fluid which causes corrosion to Transmission. Im paying $900 to correct the problem. They should have recalled the vehicles that was affected.

- North Little Rock , AR, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated while driving approximately 45 MPH and slowing while exiting the highway, the vehicle started to lose forward momentum and lurch forward. The contact had not depressed the brake pedal but instead attempted to accelerate however, the RPM increased but the vehicle lost motive power. The contact stated there was no warning light illuminated. The contact had taken the vehicle to a local dealer where it was diagnosed and determined that there were no mechanical issues found. The vehicle was not repaired. The contact stated that the failure had become recurring. The manufacturer had not been informed of the failure. The failure mileage was approximately 69,000.

- North Las Vegas, NV, USA