Bulletin No.: 21-NA-275 Please refer to the posted bulletin. This known issue is absolutely dangerous and needs to be recalled. My truck will lock up going 50 to 60 mph to a complete stop and there's no warning. Gm needs to get all these vehicles fixed it's going to hurt someone or even worse. There's no warming lamps. I'm getting my vehicle into the shop as soon as possible. This issue again is very very dangerous.

- Aurora, MO, USA

I was driving along about 45 mph and the truck was cruising in overdrive so about 1500 rmp on tachometer. I hit the gas to climb a hill as truck started to lose speed and when it tried to shift out of od to pick up speed the brakes seemed to slam on and I skidded to almost a stop. This has happened several times when climbing a hill or anytime I have to pass a vehicle or accelerate from out of overdrive. The dealer could never seem to get it to reproduce during test drive. They recently said there is a service bulletin for this exact issue and are waiting for a new valve body for transmission. My service records show I had a new valve body installed last year due to transmission pump bearing coming apart internally. The valve body is only a year old. But this is a very dangerous situation. I have to drive my truck for work and I have to be really cognizant of how hard I touch the gas and what gear I am in. If this happens to anyone while on the freeway and a semi or another vehicle is too close their truck will downshift and lock brakes and it could cost a life. It only happens under these circumstances but it has to be a recall. A service bulletin doesn't get it as someone has to have it happen for it to even be looked at. I have to drive my truck as I do not have a choice. But a service bulletin shows that GM I'd aware of the issue but they are unwilling to do a recall. A lotnof silverados are on the road and inwould hate for anything to happen. It could ruin a lot of lives.

- Fredericktown, OH, USA

The contact owns a 2021 Chevrolet Silverado 1500. The contact stated that while driving at various speeds, the vehicle hesitated while depressing the accelerator pedal. The check engine warning light was illuminated. In addition, an abnormal grinding sound was coming from the engine. The contact stated that the vehicle surged forward after experiencing hesitation. The vehicle was taken to a dealer where the valve body was replaced; however, the failure worsened upon retrieving the vehicle. The dealer was notified of the failure and informed the contact of Technical Service Bulletin: 20-NA-187. The dealer stated that there was no repair for the bulletin. The manufacturer was also notified of the failure and the contact was provided a case number. The vehicle was not repaired. The failure mileage was approximately 30,000.

- Philadelphia, MO, USA

Radiator is leaking coolant. Truck is 2 years old and this is a known issue being widely reported

- Berkley, MA, USA

Truck lost power and shut down without warning while driving in traffic. Happened twice on the way home from church with my family. First time truck shut off as we were turning across a busy intersection. Coasted off on to shoulder of highway. After several attempts truck restarted. It shut off again before reaching home. Has to call a tow truck. Has truck towed to local Chev dealer on New Years Eve. Dealer kept truck three days. Could not find problem. I picked up truck, drove home, truck shut off just before I reached my house. Coasted into driveway. Called dealer. Said bring it back. Waited two hours. Truck started so I drove back to dealership, approximately 15 miles. Truck shut off again without warning on highway in front of dealership. I sounded horn and flashed lights as I coasted across oncoming traffic into dealership parking lot. This was on Wednesday Jan 3rd. Friday afternoon dealer called and said that hey have not been able to isolate problem. Said they know they are losing communication between modules but don-??t know where. The -??fix-?? they claim is to take the cab off the truck and replace entire wiring harness! Cost is $6300. Truck has 48,000 miles on it. All highway and road miles. Can-??t afford $6300 to repair a 2.5 year old truck. I am fortunate that neither me or my family were involved in a crash due to truck shutting off unexpectedly. This is a very dangerous issue.

- Umatilla, FL, USA

Transmission lags between 1st & 2nd gear some times as long as 3 seconds making transfer case hit hard. I have had this truck at the dealer 2 are 3 times with this and other matters, the maintenance technician reports he can not reduplicate my grievance, this malfunction occurs more prominently in cold weather in morning on first take off. All so turn signal malfunction at random no particular pattern, Tech. all so unable to reduplicate.

- Quincy, IL, USA

On 6.22.23 at Lake Powell AZ this truck transmission locked up twice and nearly threw the wife and I through the windshield, very traumatic!! Happened towing a boat entering highway, had to pull to a narrow shoulder. Jarred our bodies, seatbelt into shoulder/chest. The engine light came on, had truck towed to Flagstaff Chevrolet. Had it 3 weeks. Drove home to Huntington Beach, CA without issue. Drove fine until 10.21.23 when engine light came on. Took truck to Delillo Chevrolet on 10.30.23 where purchased, they diagnosed, said Flagstaff Chevy did not program trans. computer correctly, programmed and said it was good to go. Picked up truck on 10.30.23, drove about 50 miles 11.2.23 to work and back, that night went to drive and the engine light was back on. I turned off an hour later. I drove it the next day no engine light, leaving physical therapy for my recent shoulder replacement, going 40 mph when it did the same thing it did in June! It jolted me two times nearly hitting my head on the steering wheel. The transmission shifted to 1st gear, certainly red-lining the engine. I drove the truck slowly to Delillo, just a few miles away. I told the service manager I can never drive this truck again, it is unsafe, traumatizing waiting for this to happen again. I would never put my family in this truck again. It has caused me physical and emotional trauma. The vehicle is unsafe, the jolts caused my new shoulder to hurt. It is devastating to think what would happen if I was at freeway speeds. Others need to know about this issue as well. Thank you so much for your time and what you do to ensure the safety of vehicles on the road.

- Huntington Beach, CA, USA

The contact owns a 2021 Chevrolet Silverado 1500. The contact stated while driving at various speeds, the vehicle would hesitate while attempting to accelerate. The contact stated that vehicle revved abnormally and failed to immediately respond. The contact stated that the hesitation also occurred while accelerating from a stationary start. The contact also had observed that there was a leak of fluid whenever the vehicle was parked in the driveway. The contact stated no warning light was illuminated. The contact had taken the vehicle to a local dealer, where it was diagnosed and determined that the transmission was leaking and that the transmission and torque converter needed to be replaced. The vehicle had not been repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 16,000.

- Woburn, MA, USA

Vehicle began to shudder on the highway, managed to pull off at next exit and drive to nearest gas station approximately 3 miles away from the highway. Vehicle was towed to neared GM dealership. Dealership has determined that the fault is caused by a failed or multiple failed Camshaft Lifters inside the engine. This has been reported to be a common issue with the GM 5.3L Engine with no active recalls. The vehicle shudder began on a highway during construction where the highway was restricted to one lane. There was an accident with bumper to bumper traffic where an ambulance required way. The vehicle was not in stable condition and could have caused safety risks to other drivers on the high way as well as my passengers and myself. There were no symptoms prior to the vehicle shudder, the Check Engine Light did not come on until about 3 miles of driving closer to the gas station. The Service is being warranted by GM. There are active GM tickets open. Vehicle is being serviced by Stickland Cadillac Buick GMC Chevy in Brantford Ontario Canada

- Indianapolis, IN, USA

The truck lunges sometimes, and will jerk shifting, also at variable speeds the truck will feel like it is "riding over rumble strips at a low speed" at variable speeds 30 MPH to 70 MPH. It makes for an unsafe feeling having the vehicle lunge unexpectedly, and the shuddering on the highway causes alarming panic, and reaction, and a feeling of delayed response from the accelerator. Yes, everyone says it is a known GM issue, but nothing will be done, unless I contact a lawyer. No No warnings, or lamps of any kind.

- Beckley, WV, USA

It-??s been going on for some time and have taken it to the dealership for request but with no help. The transmission keeps shuttering bucking between gears this is sometimes violent but seems to be becoming more frequent. This is mostly between speeds of 50-60mph

- Greenwich, NY, USA

Smell gasoline inside the cabin. Vehicle jerk when moving gear from reverse to drive or drive to reverse.

- Mcdonough , GA, USA

Transmission making a whining noise and delays between shifting.

- Adairsville, GA, USA

The transfer case has locked up several times causing me to wreck once. The engine misfires and does not give the MPG advertised. The life of my family has been put at risk with little to no care from the dealer after several attempts for service.

- Vail, CO, USA

My safety system service warning comes on for about 30 seconds and then goes back off. This has happened about 4 times now. The transmission causes my truck to shake randomly. My pulley is going out and the local dealer said they wouldn't replace is under warranty(even though my warranty was still is effect) because they said it looked like someone sprayed tire cleaner under the hood(I bought it from the same dealership that I took it to for this service.) The brake seem to shake already when coming to a stop. They seem as if they are wearing prematurely.

- Greenbrier, AR, USA

While vehicle is in 4-wheel drive or 4 auto or 4 L. It makes a grinding whining noise! I have contacted the dealer Newberry motors of Newberry MI 49868. I asked them about a service bulletin I saw on the noises I am hearing, and I was told service bulletins are only assigned to a vin number and not groups of vehicles. which is a lie!!! SO THE GRINDING NOISE IS BAD WHEN IN 4 WHEEL DRIVE. PERIOD. DOES NOT MAKE THE NOISE WHILE IN 2 WHEEL DRIVE. THANKS FOR ANY HELP THAT CAN BE PROVIDED!

- Engadine, MI, USA

Valve lifter failure resulting in bent rod engine failure.

- Corvallis, OR, USA

Power hesitation, along with loud knocking sounds coming from the engine. Cause truck to completely shut off while driving 35mph. No warning lights or anything came on until complete failure

- Palmerton , PA, USA

I was not personally at risk during my incident, but I can see how I could have been if my situation was a different. My 2021Chevy truck suddenly lost engine power at a traffic stoplight. It almost stalled coming to a stop. Then when trying to accelerate, it had very low power, and was stumbling. I was only a mile from home, and not busy traffic, so I managed to make it home. Driving very slowly with the engine clearly under very low power. No CEL or warning lights came on. After getting it towed to the dealer the next day, the dealer informed me it was a failed lifter and bent pushrod. After a little google searching, I found it is a common failure in newer GM V8s. I also learned my truck was built in a date window that GM issued a Service bulletin for lifter failures. According to forums and Facebook pages, Many other owners have had the same problem. Even 2-3 time failures with some owners. Even after repairs. Either in the date range of the bulletin or outside of it. My specific situation wasn't dangerous, but I could see how it could be, if I were on a busy highway, or if the truck completely lost power. As far as I see, no Recall has been issued, just many internal service bulletins over several years. And even a class action lawsuit in regards to lifter failure. My truck was fixed with all lifters replaced with an updated part number. 5000 miles since the repair. Gm did a good job with the repair, and after some communication with GM customer service, they replaced all the lifters, and not just the broken one. This gave me a bit more peace of mind, but I worry with so many failures posted online daily, and without a documented case on NHTSA this will continue. Thanks

- Rochester Hills, MI, USA

Dealer said lifters failed. Was stuck in middle of interstate for 2 hrs

- Phenix , AL, USA