2021 GMC SIERRA 1500 Unknown Or Other Problems

The coolant control valve has failed on two occasions—once during the warranty period and again approximately 18 months later, outside of warranty. Each failure resulted in continuous fan operation and fluctuating engine temperatures. Failed on around June 2024 and again December 17, 2025

I purchased a 2021 GMC Sierra 1500 Denali (VIN: [XXX] ) from J.C. Lewis Ford in Pooler, Georgia. The dealership did not disclose an active federal safety recall (NHTSA Campaign Number: 24V-xxx / GM XXX) related to engine connecting rod and crankshaft defects that can result in sudden engine failure and loss of propulsion. The Blue Certified delivery document they had me sign includes a section requiring disclosure of any open recalls, but they left the recall section blank and checked that all recalls were explained to me. No disclosure of any recall occurred during the sale. The vehicle developed engine problems within days and is currently in GMC service. The nondisclosure put me at risk of driving a vehicle with a known safety defect. I am reporting this as a dealer nondisclosure of a federal safety recall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C....

I was traveling home from work and lost all power to the vehicle while driving. No warning lights, check engine lights came on. I was able to cross traffic and park it in a business place. I had it towed to a chevy dealership for diagnostic. They said that the timing chain came off and i would need a new engine. I had it towed to a auto mechanic shop for a second opinion and they gave the same result. The vehicle is only 4 years old with 92,000 miles on it. When i lost all power to the vehicle, I did not hear any strange noises.

I was driving at highway speeds probably doing 55 and another vehicle pulled out in front of me forcing me to slow down rapidly. That’s when my wheels locked up and my vehicles wheels locked up in the middle of the highway. Screeching tires, almost like the vehicle went into park for a second. After about two seconds, I was able to continue driving a highway speed no check engine lights no error codes. It felt like I just hit something nearly gave me a heart attack. My family was in the car. It felt like we all almost died. It was terrifying. This transmission issue recall situation has happened to me more times than I can count. Now it’s almost a guarantee that if you have to shift too hard too fast it locks up the differential and it is terrifying. Every time.

This was the first time I had ever experienced the rear differential locking up at highway speeds in my truck. It was probably the day after I bought the truck. I was going down route one southbound going probably around 60 miles an hour and the wheels locked up and the vehicle felt like it was gonna come to a screeching hole. It felt like I hit something And then the wheels unlocked and it allowed me to keep driving. I thought that I might have hit the cruise control button on the steering wheel by accident and chopped it up to operator error which now I know is one of the most dangerous recall issues I’ve ever had to experience or indoor. Thank goodness my family was not with me at the time. But these issues continued on for months…

The retractable running board on the driver side retracted well my 3-year-old daughter was climbing into the back of the truck. She then fell off and to the ground. On more than one occasion, I was standing on the retractable running board on the driver side. I was buckling my daughter up in her car seat. The running board retracted in without me doing anything. I did not touch the door and had the driver's side driver door and passenger door open at the same time. This has also happened when just the passenger door was open. The running board retracts and knocks my shins into the truck body. This is quite dangerous and could easily cause great harm. I am not the only one with this issue and have read numerous complaints in online forums. I came across a potential remediation of the problem in an online forum. That...

I took my truck through a car wash and then parked at my parents house. While the vehicle was parked, the trunk latch kept releasing. The trunk popped open. I left it open but you could hear the latch continually releasing and the lights blinking. This went on for an hour and I was unable to drive home because my trunk kept unlatching! A recall was released for other Sierras but not mine. Please investigate my vin and others that may be affected.

I am experiencing a recurring issue with my 2021 GMC Sierra where the dashboard displays a “Shift to Park” warning even though the vehicle is already in Park. This typically occurs when I attempt to shut off the vehicle. The doors unlock as expected, confirming the truck is in Park, but the warning prevents me from turning off the ignition immediately. After a few seconds, the warning usually disappears, allowing me to shut off the truck. This issue is more frequent in cold weather, suggesting a temperature-sensitive electrical or mechanical fault. Based on research and community reports, this appears to be a known issue across multiple GM vehicles, often linked to a faulty micro switch or wiring harness in the shifter assembly. I am concerned about the safety implications, especially if the vehicle fails to shut off properly or if the issue worsens over time. GM has not issued a...

Coolant control valve failure. Instantly reduces power on truck. National back order on parts. No remedy.

The plastic frame of the rear sliding window failed. This has allowed water to enter the cabin, which can cause mold and other health issues. This seems to be a common issue with these trucks. My truck has a certified preowned warranty and GMC said they would only cover part of it. They charged me $400 as a deductible, which there should be no deductible per certified preowned warranty. I feel like GMC needs to put out an official recall.

Engine experiences missing when accelerating in lower speeds ...also now, and since driving for a few thousand miles, f umes are entering cabin frequently and causing nausea, 'headaches and burning of mouth, lips and eyes .....all the time. My youngest granddaughter got sick and so did my oldest son just this past weekend! As far as I know , police or dealership never inspected , nor did they acknowledge it! No warning lamps appeared

When I am in park my engine shuts off the light goes from green to orange which indicates it’s still on electrically. I have to turn on/off my vehicle multiple times for it to turn off fully. It’s an intermittent problem.

Dealer keeps ignoring engine knock noise states its normal , mpg is down dramatically . Shift to park , vehicle only has 34k miles and dealer does not want to repair under warranty due to vehicle being a 2021 Battery keeps draining for no reason , new battery added still does the same thing

The transmission is constantly whirring, rattling, and screeching.

I've noticed rough or jerky gear shifting when accelerating, rough and reduced propulsion, loss of power. Dealership repaired power torque converter but the truck continue to have the same symptoms.

We NEVER RECEIVED A RECALL NOTICE FYI . This vehicle has been serviced consistently.never an issue. Driving on [XXX] very busy! Truck literally stopped in the middle of the freeway in a very bad location. Desert. Noon. Kids with us. Could have died. Preliminary eval: engine seized, piston rod failure. Not sure the rest - we have to tow it home first. Failed while traveling. Please call for more information if needed. [XXX] [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My tailgate will randomly open on its own. I’ve had several instances( 5 or 6 times so far) when I’ve had open on its own. Only once so far when i was driving. Luckily, i was on my private road without anything in my bed that could fall out. I often carry mountain bikes over the tailgate which could pose a serious danger if the tailgate were to open when driving. Also earlier this evening when the tailgate came down on its own while driving, when I got to my destination, I was unable to open the tailgate at all from outside the vehicle. It is apparent the button to release the switch is malfunctioning. I was able to get it to open by using release button inside the vehicle.

Transmission, rear wheel lock up issue. Dealer performed recall notice work. Truck still has same issue after dealer visit. When issue starts, feels like you ran over something in the road, All warning lights are on, loss of power to engine and the engine did quit working once. Door locks continue to cycle repeatedly, multiple screen warnings appear on dashboard. It appears that everything that could go wrong happens at once. Have heard transmission valve control modules is a major problem with GM 10 speed transmissions.

My vehicle was issued an OTA ( over the air update ) automatically, and the update failed, leaving the screen in my vehicle inoperable, with a message displayed stating " Update failed return to dealer" My vehicles radio/information system is now inoperable. The blue-tooth calling capability is also inoperable. This is a safety issue due to the fact that I am a resident of Minnesota and we have a law that states it is illegal to use your phone while driving. In addition, I am unable to receive severe weather alerts via the radio and do not have the ability to make phone calls in my vehicle in the event of an emergency since it is illegal to use my phone in MN while driving. This is a serious safety hazard The GMC dealer (Mills GMC in Baxter, MN ) that the vehicle is currently at has stated this is...

The transmission/torque converter is causing (bucking, kicking, jerking, slipping, difficulty when taking off, shuddering during driving, fishbite, and chuggle). Its becoming a safety hazard now because its putting me and others at risk for an accident. The vehicle will hesitate to go in which if traffic may be rear ended by another vehicle. During weather/rain the vehicle will lose traction and the rear wheels will spin causing an accident. Problem has been reported to dealership multiple times and the only solution they can provide is keep driving the vehicle. Vehicle has no warning lights at all or any other symptoms of problems prior to when the components started to fail. The issue first happened around February 2024 and remains to be an issue to this present day. I've been the dealership more than 6 times with no solution/fix. I'm concerned for my safety now and need this issue addressed ASAP.

On [XXX] at approximately 3 pm I left my house and was traveling on [XXX] in Fort Mohave Arizona I was only traveling 7 miles. When I looked at the temperature in the cab was 121 degrees a few moments after the display system went black and never turned back on. I arrived at the store 4 minutes after the display shut off with no warning lights or any type of notification on my phone, I had rolled down the windows to get air in the cab to see if that would help cool down if needed. I was in the store 20 minutes. I returned to the truck turned it on and everything was normal, from there I drove back home nothing happened on my drive back the display was working. At 8 30pm I was traveling on [XXX] Driving towards a casino called Avi. I had the driver's...

The Flex Tailgate has on multiple occasions has malfunctioned in cold temperatures. I have had instances where I can get it open when I have vital supplies in the bed of my truck because of the Tonneau Cover being on (I have a hard cover made for this truck) and the tailgate malfunctioning. I have also had an instance where my tailgate opened (after clicking shut) while driving without the notification coming up on my dash. I could've been held liable if my equipment fell out and caused an accident. Moral of the story this truck as a lot of issues when temps are below freezing even after being warmed up for 15 minutes or longer. I wouldn't recommend this truck based on the function of the Flex Tailgate. I would prefer a classic a handle and less tech now that I have seen it fail so many times.

5 days after purchasing and While driving down the interstate at 80 mph, there was a loud clunk at the same time the back wheels locked up for a split second, long enough to burn the tires and throw everyone in the vehicle forward then the vehicle continued on. It happened three more times, we trailered it and brought it to the dealer. They said nothing is wrong with it. However, I was able to locate the previous owners who stated they'd been bringing it to several dealerships to have it taken care of for the past six months and every dealer said that nothing is wrong with it. But the same thing happened to them for six months. One mechanic in Idaho even replaced the motor trying to fix it and it still continued. The dealer I purchased from never mentioned it having a new motor, and I pulled...

I have HD surround vision cameras. I was parallel parking very slowly. The back end of my truck was in so I was watching the camera to see the front right of my truck and the back left of the other vehicle. I could see both vehicles including the road between them. There was space between the vehicles on the camera when I hit the other car. I called Sewell Buick Gmc and explained the camera might need calibrating. They sent a loaner car and picked mine up, When the driver arrived I explained the situation. It surprised his so I said get in my truck and put in reverse to activated the camera and watch me as I walk toward the right front tire. He saw mw as I approached, however, when I got right next to the tire I disappeared from she screen. GM said the vehicle was...

I have a GMC Sierra 2021 Denali. The vehicle currently has less than 16,000 mile and is at the dealership service department for lifter replacement. This is an extensive repair considering how new the vehicle with low miles. From extensive online research and collaborating with others, this is a common concern with multiple GMC vehicle that's been on GMC radar starting in 2017. GMC haven't yet issued a recall for these products and the consumers are footing the bills. Please put pressure on GMC to rectify their wrong.

I have a 2021 GC Sierra 1500, The guidance lines in the display when in reverse go from non-existent to barely visible and are not usable especially in sunlight. The service man at Miller Chevrolet in Marianna Fla says GMC is aware of the problem, that it was caused by the last update download and will be fixed by another download to correct the problem. He also says the same issue is nationwide and all trucks have the issue which I find hard to believe. 1.If that were true it would be a simple matter of a few lines of code to correct the problem. 2. I have been chasing this problem since October and have now made four trips to the dealership. 3. I cannot believe all trucks have this issue and also I suspect the same backup system is in all GMC vehicles regardless of type. 4. I...

The driver-side mirror on my 2021 GMC sierra is unusable at freeway speed. When traveling at freeway speed the glass moves due to wind and causes the reflection in the mirror to be blurry. The reflection from the mirror is blurry to the point that I'm unable to identify objects in the mirror and it is difficult to gauge size and closing speed of any objects in the mirror. The issue has been with the vehicle since I purchased it new in June of 2021. The issue has been reproduced by two different dealership service centers and the entire driver-side mirror assembly has be replaced twice with the issue persisting. I have videos showing the issue but they are too large of files to upload on this form.

My truck shakes/shutters at random times. while steadily driving at constant speed and/ or shakes/shutters even more when I try to accelerate.

The only way to get the heater to work on your feet is to turn off defrost, turn on only feet, turn on AC and sync both sides. I live in North Idaho and when you do this your windshield fogs up and freezes. I have taken this to the dealership and was state "Works as designed by GMC". To me this is unacceptable. I drive 90 miles each way to the airport and have to decide what condition i can live with. Completely frozen feet and a clear window or the reverse.