2021 Chevrolet Suburban: sudden loss of power

Filed Sep 15, 2026 · Engine · IL

Sudden Loss of Power & Shaking: The misfire itself causes a drastic drop in acceleration. If you are merging onto a highway or trying to pass another vehicle, the sudden loss of power can leave you stranded in the path of oncoming traffic. No Stability Assistance: Because StabiliTrak and Traction Control are automatically disabled, the vehicle loses its ability to correct for skids, fishtailing, or hydroplaning. In rain, snow, or emergency swerving maneuvers, a heavy SUV becomes much harder to control. "Limp Mode" (Reduced Power): To prevent the unburned fuel from a misfire from destroying the expensive catalytic converters, the vehicle may force itself into a "Reduced Engine Power" or "Limp" mode. This limits your top speed (often to around 30 mph), which is highly dangerous if you are in the fast lane of a highway. Violent Transmission Shifting: To protect the drivetrain from the erratic power dips of a misfiring engine, the vehicle's computer will maximize transmission fluid pressure. This causes the Suburban to shift gears incredibly hard, which and feel as though the transmission is exploding

Filed Sep 14, 2026 · Engine · FL

I am filing this complaint regarding a serious engine and safety issue with my 2021 Chevrolet Suburban equipped with the GM 6.2L engine, with approximately 45,500 miles. The vehicle has developed a noticeable and abnormal shaking/vibration coming from the engine. At the same time, the vehicle experiences a significant loss of power, at times becoming so severe that the engine feels as though it is going to shut off. This is a serious safety concern. A sudden loss of engine power could occur while driving in traffic, accelerating, merging, or traveling at higher speeds. The vehicle may become unable to accelerate properly or could potentially stall, creating a significant risk of a collision. I am concerned that this issue may be related to a defect affecting GM's 6.2L engines. The fact that this is occurring at approximately 45,500 miles is particularly concerning, as an engine should not experience this type of severe shaking and loss of power under normal operating conditions. I respectfully request that the federal safety agency investigate this issue and determine whether there is a safety-related defect affecting the GM 6.2L engine used in the 2021 Chevrolet Suburban and other GM vehicles. I am reporting this because I believe the sudden loss of power and potential for the engine to shut off could endanger the occupants of the vehicle as well as other motorists

Filed Sep 14, 2026 · Engine · FL

I am filing this complaint regarding a serious engine and safety issue with my 2021 Chevrolet Suburban equipped with the GM 6.2L engine, with approximately 45,500 miles. The vehicle has developed a noticeable and abnormal shaking/vibration coming from the engine. At the same time, the vehicle experiences a significant loss of power, at times becoming so severe that the engine feels as though it is going to shut off. This is a serious safety concern. A sudden loss of engine power could occur while driving in traffic, accelerating, merging, or traveling at higher speeds. The vehicle may become unable to accelerate properly or could potentially stall, creating a significant risk of a collision. I am concerned that this issue may be related to a defect affecting GM's 6.2L engines. The fact that this is occurring at approximately 45,500 miles is particularly concerning, as an engine should not experience this type of severe shaking and loss of power under normal operating conditions. I respectfully request that the federal safety agency investigate this issue and determine whether there is a safety-related defect affecting the GM 6.2L engine used in the 2021 Chevrolet Suburban and other GM vehicles. I am reporting this because I believe the sudden loss of power and potential for the engine to shut off could endanger the occupants of the vehicle as well as other motorists

Filed Sep 14, 2026 · Engine · FL

I am filing this complaint regarding a serious engine and safety issue with my 2021 Chevrolet Suburban equipped with the GM 6.2L engine, with approximately 45,000 miles. The vehicle has developed a noticeable and abnormal shaking/vibration coming from the engine. At the same time, the vehicle experiences a significant loss of power, at times becoming so severe that the engine feels as though it is going to shut off. This is a serious safety concern. A sudden loss of engine power could occur while driving in traffic, accelerating, merging, or traveling at higher speeds. The vehicle may become unable to accelerate properly or could potentially stall, creating a significant risk of a collision. I am concerned that this issue may be related to a defect affecting GM's 6.2L engines. The fact that this is occurring at approximately 45,000 miles is particularly concerning, as an engine should not experience this type of severe shaking and loss of power under normal operating conditions. I respectfully request that the federal safety agency investigate this issue and determine whether there is a safety-related defect affecting the GM 6.2L engine used in the 2021 Chevrolet Suburban and other GM vehicles. I am reporting this because I believe the sudden loss of power and potential for the engine to shut off could endanger the occupants of the vehicle as well as other motorists.

Filed Jul 27, 2026 · Fuel system · 92,709 miles · VA

The contact owns a 2021 Chevrolet Suburban. The contact stated that while driving on the highway, the vehicle experienced reduced engine power and failed to exceed 30 MPH. A message pertaining to the deceleration was displayed. The following Monday, the vehicle failed to exceed 35 MPH, and a friend followed the contact while driving to the dealer. The dealer recommended a fuel filter replacement. The contact declined the repair because the fuel filter life was at 47%; however, the dealer proceeded with the replacement. The contact provided the diagnostic trouble code to an independent mechanic, who informed the contact that the failure was associated with TSB Numbers: 20-NA-197 and 18-NA 361. The contact then advised the dealer of the TSBs, and the dealer determined that the fuel pump module and fuel tank module needed to be replaced. The vehicle was repaired. Additionally, the contact stated that the second-row passenger’s side seat belt buckle failed and was replaced under an extended warranty, although the part was previously replaced under a recall. The manufacturer was notified of the failures several times, but no assistance was provided. The failure mileage was approximately 92,709.

Filed Jul 26, 2026 · Fuel system · VA

Pulled out in 4 lane traffic. Got almost to 55mph. Vehicle lost all power, slowed down and auto shifted to neutral, vehicle stopped and went to park. Vehicle would not start back nor transition to Neutral to remove from highways. 2021 suburban with just 35,000miles. Shut down a lane on a 55mph highway. Code P129F

Filed Mar 20, 2026 · Electrical, Steering · NE

I am submitting this complaint to report a serious safety issue involving my 2021 Chevrolet Suburban equipped with the 3.0L Duramax diesel engine. The vehicle has experienced a recurring problem related to the engine wiring harness. While driving, the vehicle will unexpectedly stall without warning. At the same time, there is an immediate loss of power steering assist, significantly reducing the ability to safely control the vehicle. This creates a dangerous situation, especially at highway speeds or in traffic. The failure appears to be linked to a defect or malfunction in the engine wiring harness, which may be causing intermittent electrical interruptions to critical engine systems. There were no prior warning signs sufficient to prevent the incident. This issue poses a substantial safety risk not only to the driver and passengers but also to other motorists. Sudden engine shutdown combined with loss of steering assist increases the likelihood of a crash. I believe this may be a systemic defect affecting other vehicles of the same model and configuration. I urge the federal safety agency to investigate this issue and determine whether a recall should be issued. Vehicle Information: Make: Chevrolet Model: Suburban Year: 2021 Engine: 3.0L Duramax Diesel

Filed Mar 12, 2026 · Engine · OR

While driving the Engine warning light, service ESC light, and collision light all came on and an engine knock started. I also experienced a loss of power at the same time. Car was taken to local Chevy dealership for evaluation and repair. Dealership advised that they dropped the oil and found metal shavings in the oil. After further investigation, we were advised that it was a crankshaft connecting rod failure. We have an extended warranty and were waiting to hear back on repair coverage. GM denied the repair as this vehicle is not part of the active recall. Our warranty company also denied the repair stating we did not have adequate records of oil changes. Receipts for oil and filters were provided.

Filed Oct 4, 2025 · Engine · AZ

Engine while driving completely seized up. Crank shaft, cam shaft and oil pump water pump replaced. Low oil pressure alarm code present then sudden loss of power. Piston blown. There are similar recalls to 2021 suburbans however, this specific model is not in the recall. I was told I need a completely new engine. The car died in the middle of traffic and police had to call an emergency tow truck.

Filed Sep 2, 2025 · Driver assistance, Engine · TX

I was driving when I received messages saying service ESC, Forward collision System Unavailable, & Service Traction Control. The vehicle began to shake hard when I applied brakes, had loss of power when pressing the gas pedal, and sounded like metal grinding. All of this put my children & I at risk as we were on interstate 35 with cars flying past us and I’m losing power. Initially the spark plugs and coil was were changed to no repair. It was towed to a dealership where they confirmed the lifter & cam failed which put metal in the oil. My only option is a full engine replacement costing 20k on a vehicle that’s 4yrs old. It’s not ok that I have to spend that in order to get my 70k car drivable. Im now without a car, still paying a car note, unable to get my kids places, and having to get help from friends all bc GM can’t build a quality vehicle. I also haven’t been able to get a loaner car. This isn’t happening in only the 6.3L. This is a widely known issue with the 5.3L as well. *There were ZERO warning signs that something was wrong. Drive just fine that morning*

Filed Aug 8, 2025 · Engine · TN

Was driving about 45 mph on 2 lane road. All of a sudden, without warning we lost power (had no propulsion). Luckily there was a residential side street that we were able to turn onto and get off of the highway with no shoulder. We coasted to the side of the street and called a tow truck. Had we not been able to get off the road, we would have been dead in the road, blocking an entire lane of a busy 2 lane highway without a shoulder to pull off on. There was no warning prior to incident but a message did appear during the incident. I believe it said "Loss of propulsion." We turned off the vehicle, then tried to restart it. Engine attempted to restart, but it made a horrible noise & wouldn't restart. Still had battery power. Vehicle was towed to a local dealership where it is currently being evaluated. We know of a massive recall on the 6.2 l engines. Ours is a 5.3 l engine. So far I'm seeing many people having problems but no official recall for the 5.3 l engines that are having THE SAME issue as the massively recalled 6.2 engines. This needs to be looked at. Our Vehicle only had less than 30k miles on it. We bought it new and have done routine maintenance.

Filed Jul 7, 2025 · Engine · AZ

Vehicle lost power, debris in cylinder from internal damage, crank case leaking air, oil leaking into cylinder, P0300, P0308, and P050D