1. Lane Keeping Assistantance: The green vehicle indicator on the dashboard will disappear and stay off while driving. When it is off, it is unsafe. 2. Parking Collision Warning: The front and back sensors will disappear and become nonfunctional while driving and parking. Sometimes they activate for no reason as well. 3. Both exterior mirrors: After starting the engine to drive off, both exterior mirrors will lower automatically from my setting. After the truck is started and driven off, they must be rest again.

- Victorville , CA, USA

My multipro tailgate on my 2020 GMC Sierra 1500 unlatched while a trailer was attached and backing up said trailer. The trailer jack post proceeded to buckle the upper part of the tailgate assembly causing extensive damage resulting in over a three thousand dollar repair bill. If the tailgate had released while a child was in close proximity, serious injury may occur. The tailgate has inadvertently released twice in the five plus years I have owned it, the first time as I was traveling down a highway at over 60 mph. This could have endangered a vehicle to my rear if cargo had been released on to the road. I have reached out to a local dealership for repairs and assessment, no real way of troubleshooting something that has happened twice in five plus years. The scan did not show any codes. the info center does notify you if it is released but not before it takes place and after the fact may be too late in some circumstances as it was during the second occurrence. There has been a recall on 2500 and 3500 models with the exact same tailgate but not the 1500 models. 820K vehicles affected but not on the 1500's.

- Rineyville, KY, USA

1. On 05/9/25, the exhaust emissions system malfunctioned, triggering diagnostic trouble code P2C7A (exhaust emissions system failure). This repair, the seventh attempt since June 2024, addressed the same recurring emissions issue previously involving replacements of components such as the NOx converter (02/18/25, 03/13/24) and EGR valve (02/18/25). The vehicle is available for inspection upon request. 2. The P2C7A failure risks limp mode, reducing vehicle power unexpectedly, which is hazardous on highways, especially while towing. Exhaust emissions system malfunctions release excessive pollutants, posing environmental and health risks to others. 3. Yes, the P2C7A code was confirmed by dealer during the 05/9/25 repair, following prior confirmations (e.g., 03/31/25-?"04/05/25. 4. The vehicle was inspected by Young Chevrolet-Cadillac during multiple repairs (e.g., 03/31/25, 05/9/25). 5. Yes, the check engine light and OnStar emissions alerts appeared prior to the 05/9/25 repair, first noted ~June 2024 (P2C7A onset). Exhaust smell and reduced fuel economy were observed intermittently. Symptoms persisted post-03/31/25 repair, leading to the 05/23/25 service.

- Brighton, MI, USA

Transmission shurtting, jerks, and vibration, bad torque converter bubble and pelling paint. It feel likes engine is lossing power

- Santa Fe , TX, USA

6.2 liter engine fail- replaced at new cost, 20,000 miles later another 6.2 engine failed. unable to get new engine due to GMC finally recalling the engine. My VIN is not included in the recall. I now have no vehicle to drive but still have a loan to pay.

- Sioux Falls, SD, USA

Vehicle was going in for warranty recall; however, i requested they look at the DEF system as my DEF gauge would bounce between full and empty; along with, alert me of going into LIMP mode. GM Maintenance updated the recall and noticed that the DEF tank sensor failed and required to be replaced.

- Brighton, MI, USA

No warning; picking up child from daycare. went to depart daycare when my dash lit up like a Christmas tree with various errors, alerts, warnings; along with, not being able to start. had to be picked up by spouse and get the truck towed to the dealership for maintenance. Maintenance tech discovered that the grounding straps for the truck needed to be replaced / resulting in a complete electrical failure of the vehicle.

- Brighton, MI, USA

Engine light came on while driving / aligned to transmission temp sensor error and brake sensor GM Maintenance was able to diagnosis that the Temperature Loop Coolant Pump had failed and needed to be replaced.

- Brighton, MI, USA

Vehicle drop in gear / down shift while driving on the highway. went from 75MPH down to 55MPH due to high RPM revs.

- Brighton, MI, USA

Rear window is leaking top coners from seal or plastic creating black mold inside of truck

- Leola, PA, USA

I purchased a 2020 GMC Denali Sierra 1500. My oil light has came on twice and I have taken it into the dealer and dealer has said that that's normal. That car loses oil. I'm retired so I do not utilize the vehicle every day I think since I've had the vehicle I've put on several thousand miles very very low mileage put on. And I'm being told that I need to check the oil basically before I take the vehicle anywhere. During the first time when I bought the vehicle in when the light came on the mechanic said in the paperwork from GMC service that my engine oil was extremely low. This last time that I did take it in, I have some type of mechanical background, so I pulled the dipstick out and it was halfway full with oil. I took a picture of that dated the picture and said I took it in before service while when I took it into the service department of course when I came home, they said that everything's fine and so on and so on and that didn't sit well with me. So I went ahead and let the car settle. Let the car cool down several hours later. I went ahead and checked the dipstick and the dipstick was full. They went ahead and put oil into my vehicle and told me that everything's fine. And I have noticed that there are lawsuits out in regards to oil consumption issues on these vehicles. When somebody spends the amount of money they spend for these vehicles we should not have to be checking the oil almost every time we drive it. I've had multiple vehicles on 50 years old and I've never had to check the Oil like it was 1914 before you go on a trip or even drive your vehicle. I am not trying to blame the Dealership only being told that everything's fine but GMC the company needs to rectify this problem because there is going to be a time that people are going to forget about the oil and burn up an engine and then you're putting them out thousands of thousands of dollars because of a mistake GMC made they're trying to cover it up as you see with the current recall in regards t

- Woodbury, NJ, USA

I have taken my vehicle to 3 seperate mechanics (GMC, AAMCO and Independent). They all agree that my valve body inside the transmission must be replaced. The problem is that valve bodies are on a national back order and cannot be fullfilled for months, putting my transmission at risk for further failure. Reading online forums, there are many GMC owners facing this same issue. The mechanics at GMC are requesting that I change out my entire transmission, since that will be a quicker solution than waiting months for that valve body. Now, I am being told that they are having difficulty locating an original manufactured transmission. This puts me in a serious bind because my truck is my only vehicle and there are no valve bodies or transmissions to fix this issue. My truck is only a 2020 and I just surpassed 100k miles. There were no dashboard warning lights that indicated my trucks problem. Only the fact that my truck is shuddering when shifting gears and that a diagnostic tool had to find the source of the problem. This problem started about 5 months ago and has progressivly gotten worse.

- El Paso, TX, USA

Shift to park message appears when in park and engine is turned off. Transmission control had an internal circuit failure. Park not fully engaged and vehicle could roll. Problem confirmed by dealership. Prior recalls for earlier gmc models but not my year.

- Euless, TX, USA

The Transmission cooler lines broke and spilled out all the oil/fluid on my 2020 GMC Sierra Elevation pick-up truck. Once all the fluid was spilled out the Sierra truck would no longer move. The Sierra truck was towed to the dealership I originally purchased the vehicle. The dealership was Cranbury Buick GMC. The dealership mentioned that the hoses broke/leaked from the crimped housing at the ends of the hoses. The dealership stated that the original OEM transmission cooler line hoses were discontinued and new OEM replacement transmission cooler line hoses were created. Please see the attached dealership bill/invoice for the parts and labor to fix the cooler line issue. I feel this issue should be a recall on all 2020 GMC Sierra trucks, especially if GM replaced the original OEM hoses with newly created OEM hoses Thanks [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Monroe Township, NJ, USA

Water entering from the rear window causing rear seats and roof hard cover to get wet and cause a wet odor (humid). 2020 GMC 1500 AT4

- Houston, TX, USA

Shift to park error message to turn vehicle off when already in park.

- Lecompte , LA, USA

There has been a recall on the 2020 sierra 1500 for the driveshaft which causes shuddering and vibration which my vehicle is exibiting but my vin is not on the recall list

- Miami, FL, USA

My truck 2020 gmc sierra 1500 AT4 denali is not working properly since July 2024. I took it to 2 different dealership to get a diagnostic and i finally ended doing the repairs for brake issues. I have been towed 6 or more times and almost experienced 2 car accidents since I drive the truck after the supposedly repairs where done but i ended stranded again with no brakes. The dealership has repair the truck 3 times but im still getting sevaral codes the fact that i had to pay out of pocket and have to deal with this and expose myself to danger and my family in driving a vehicle that is no safety condition its absurd. I call several times the recall GM hotline and i was told GMC 1500 are included in the recalls just not the AT4 and i have a family member with the same truck and same issues she ended up trading in the truck recently since she kept experiencing the same issues over and over again just like me.

- Houston, TX, USA

The rear sliding window leaks water inside the cab every time it rains. With water getting into the cab the issue of mold has begun and that could be a serious factor to any children or adults that ride inside the cab of the truck. There is also rust issues that are notable under the rear seats of the vehicle. Water inside the cab can also interact negatively with any electrical components of the vehicle. I tried to get ahold of the dealer and they always say they don't have time to get my truck in. I have read that this has happened to other vehicles that are the same year and model and they just fix it with caulk which does not seem appropriate for a almost new vehicle. The vehicle has not been inspected. There were no warning lamps prior to this issue. A possible symptom was that my back up camera stopped working for a day right after a rain.

- Corning, CA, USA

Rear window leak causing whole inside back to get soaked. Have paid hundreds of dollars to have sealed didn-??t work. New window didn-??t work it still leaks. It-??s going to cause interior to mold and body to rust. Dealership and glass business both say it-??s body issue and they have seen many GMC and Chevrolets with this issue. Google show 1000s with same problem.

- West Lafayette, IN, USA