2021 Chevrolet Tahoe: sudden loss of power

Filed Sep 23, 2026 · Engine · WA

The vehicle suffered complete internal engine failure due to a snapped timing chain on startup. The vehicle turned over via the starter motor but failed to start. A professional diagnosis confirmed the broken timing chain caused extensive valve-to-piston damage, requiring a full engine replacement. This failure appears to be a direct consequence of the known 6.2L L87 V8 engine crankshaft and connecting rod manufacturing defects. Severe mechanical resistance or violent rotational harmonics at the crankshaft level place un-engineered stress on the timing drive system, causing the chain to snap under startup torque. All broken components are preserved and available for inspection. The defect creates a severe risk of sudden, total loss of propulsion while driving. Had the compromised timing chain snapped at highway speeds rather than on startup, it would cause immediate engine seizure, a sudden loss of power steering, and a loss of power brake vacuum assist. This leaves the driver unable to accelerate or safely steer out of active traffic, creating an extreme risk of a high-speed crash.The broken timing chain and total engine destruction were officially diagnosed and confirmed by professional automotive repair technicians.The damaged components have been inspected by independent repair representatives. The vehicle has not yet been inspected by General Motors because this specific VIN is excluded from the current recall scope. There were no warning lamps, check engine lights, or diagnostic trouble codes (DTCs) prior to parking the vehicle, and no outward symptoms of severe engine stress were present until the complete no-start failure.

Filed Sep 1, 2026 · Brakes, Driver assistance · 118,000 miles · MO

The contact owns a 2021 Chevrolet Tahoe. The contact stated that while driving approximately 70 MPH, the message "Service ESC" was displayed, and the check engine, traction control, and Forward Collision Avoidance warning lights were illuminated. The vehicle started shaking and then lost power. The vehicle was pulled over to the side of the road, parked, and then turned off. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was 118,000.

Filed Aug 28, 2026 · Engine, Transmission · ID

My vehicle had a pop and loss of power on the highway. After pulling over, I did not have a check engine light but did connect my code reader and found a P308. I felt unsafe to drive so I had it towed to a shop. I later found out the DOD system or lifter on valve #8 has failed and needs replacement. Factory recommends oil change at every 7k miles, I did them at 4K. My oil pressure was up to par with the small window of real time allowable oil pressure. The design was great on paper but one of the worst engines GM has ever made. I sincerely hope there is enough people complaining about these 2021 GM 6.2 & 5.3 engines!!

Filed Aug 8, 2026 · Fuel system · MO

I was driving on the highway and my car lost power and then had to shut down. I am now getting error code P129F. which is a known recall for the fuel pump control module. When I put in my VIN, it doesn’t show my car part of it, but it is a 2021 Tahoe experiencing the exact same issue and getting the same error code that is part of the recall. I also read that it is part of the federal emissions warranty, which is eight year 80,000 miles. My car has 59,000 miles on it and I verify that it’s still under warranty from that standpoint. I want to take it into the dealership on Monday, but I need to know what my options are to get it repaired for free under this recall since currently my car is not coming up via this VIN under this recall

Filed Aug 2, 2026 · Airbags, Steering · MI

-On the date of Monday XXX at approximately 4:30 pm est I was traveling on [XXX] and transmission felt like a possible slip happened in transmission. At approximatively 4:45pm est I made it home tried to back vehicle into parking space and reverse was lost. Vehicle didn't and wouldn't shift into reverse. I had to push vehicle in spot backwards. No check engine or warning lights were displayed on dash. - On Tuesday XXX. I contacted [XXX] of [XXX] approximately at 8:30 am est. [XXX] answered. I explained the symptoms and asked If I could bring in within the hour or so. He stated it would be fine to bring in. - At approximately 9:10 am est My girlfriend and [XXX] daughter got in vehicle. Started vehicle no service lights were on, but had no reverse still no reverse. My girlfriends mother was following us to pick us up at dealership as we dont have a 2nd vehicle. We started out driveway to [XXX]. I had no problems at 1st then prior to the intersection of [XXX] the Vehicle lost control on its own. The sequences happened fast and abrupt. 1. Vehicle downshifted roughly to about 3 gear 2. Lost power steering 3. engine over revved 4. vehicle pulled right. During this time as a professional trained driver. I removed us off [XXX] off road way on to [XXX] (To the right) to avoid being in an accident. I would say that the speed was roughly 20MPH at turn as I was avoiding the accident that could of potentially happened. I was not on asphalt the whole time to make turn as I had a limited vehicle (Not properly functional). I was able to stop at [XXX] to stop. Stopped on Brigantine is when I pointed out to my girlfriend that the lights just came on. in the meantime, we received a phone call from [XXX] (Girlfriends mom) asking where we went as she didn't see us. We explained to her situation, and she met on Brigantine and followed us to dealership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 26, 2026 · Engine, Fuel system · SC

The engine in my 2021 Chevrolet Tahoe High Country equipped with the 6.2L V8 (L87) experienced a catastrophic failure. While driving, the vehicle suddenly lost power, displayed a “Service ESC” warning, illuminated the check engine light, and unexpectedly shifted into Neutral. After stopping the vehicle, it would not restart. The dashboard would illuminate, but the engine would only produce a faint clicking sound and would not crank. The vehicle was towed to a Chevrolet dealership, where it remains available for inspection. How was your safety or the safety of others put at risk? This failure occurred while I was driving, causing an unexpected loss of power and propulsion. The vehicle became disabled without warning, creating a significant risk of being struck by surrounding traffic. Losing the ability to accelerate or safely maneuver a full-size SUV in traffic placed both me and other motorists at risk of a serious crash. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The vehicle was towed to an authorized Chevrolet dealership, Crews Chevrolet. The dealership confirmed that the engine had catastrophically failed and advised that it qualified for replacement under General Motors’ special coverage program for the 6.2L L87 engine. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Yes. The vehicle has been inspected by an authorized Chevrolet dealership. General Motors has authorized replacement of the engine under its special coverage program. No police report was filed because there was no collision.

Filed Jul 2, 2026 · Engine, Fuel system · IL

DATE: 06/17/2026 The engine shuts off without warning while I am driving, recurring roughly every 10 miles. When it stalls, the dashboard and electrical accessories stay on, but the vehicle loses motive power, along with power steering assist and power brake assist, which is extremely dangerous at road speed and in traffic. This began immediately after dealer service completed on 6/18/2026. During that visit the dealer performed two safety recalls (N252494000, the "L87 Engine Loss of Propulsion" PicoScope inspection with oil change; and N252510321, ECM software reprogramming) and a valve lifter replacement that required removing both cylinder heads. The vehicle was running and fully drivable when I dropped it off, and was returned stalling repeatedly while driving. It never did this before the service. At first the engine would not restart after stalling. The dealer replaced the starter; it now restarts but continues to stall every ~10 miles. A dealer diagnostic scan recorded numerous "Lost Communication" codes across nearly all control modules, plus control-module input-power codes showing low voltage and power-circuit correlation faults (e.g., U3505, U3018, U3007) and an active loss-of-communication code for the power steering module — consistent with an intermittent loss of electrical power or ground affecting engine control. The engine passed the recall's connecting-rod/crankshaft (PicoScope) inspection, so this is not the recalled bearing failure mode. The vehicle is currently at the dealership and is undrivable. The dealer has ordered a new engine and apparently also a new radiator for reasons unknown. No crash or injury has occurred to date, but the vehicle lost power while on the freeway at speed multiple times. A GM customer assistance case is open. Repair orders and the diagnostic scan are available on request.

Filed Jun 30, 2026 · Engine, Fuel system · IN

The engine's Dynamic Fuel Management (DFM) lifter failed and damaged the camshaft at around 70,700 miles. The broken components are available for inspection upon request. This failure put occupants at risk because the vehicle suddenly lost power, began shaking violently, and could not accelerate safely in traffic. This unexpected loss of propulsion created an immediate collision hazard. The problem was officially diagnosed and confirmed by a repair service center. It has not been inspected by police or insurance representatives. There were no advance warning signs. At the exact moment of the failure, the check engine light started flashing, the car began shaking heavily, and the engine made a loud knocking sound.

Filed Jun 10, 2026 · Engine · TX

While driving my 2021 Chevrolet Tahoe, the check engine light illuminated. Shortly thereafter, the engine began shaking severely and I heard clicking and popping noises from the engine compartment. The following morning, the vehicle was barely operable, shaking excessively and unable to properly reverse. Due to the unsafe condition, I had the vehicle towed to the dealership. The dealership diagnosed a failure involving all 8 lifters on one side (bank) of the engine, requiring extensive engine repairs. My vehicle has approximately 74,000 miles, which I believe is low mileage for such a significant internal engine failure. The symptoms included severe engine vibration, misfiring, loss of performance, and the potential for loss of power while driving. This is not the first major failure I have experienced with this vehicle. In approximately April 2023, when the vehicle had about 32,000 miles, it unexpectedly shut off while I was reversing in a roadway. The dealership diagnosed a failed fuel pump control module (fuel pump modulator). Similar failures were later identified in recalls and corrective actions affecting other GM vehicles. I am concerned that my vehicle has experienced multiple failures involving components that appear to be associated with known issues affecting GM vehicles, yet my Tahoe was not included in applicable recalls. These failures created significant safety concerns, including unexpected engine shutdown, loss of vehicle operation, and potential loss of power while driving. I respectfully request that the federal safety agency investigate whether my 2021 Chevrolet Tahoe vehicles should have been included in existing and future safety recalls related to these defects and other known defects that GM vehicles are experiencing with the motor, transmission and other parts. Note: No invoice is available yet as I am seeking GM assistance due to no warranty status. Estimated repair cost from dealership is up to $8,900.

Filed Apr 12, 2026 · Driver assistance, Engine · CA

The component at issue is the engine, which suffered a sudden and catastrophic failure due to unknown causes. At no time prior to this incident were there any warnings, symptoms, or indications of an underlying mechanical defect that would have allowed for preventative action. While operating the vehicle on the highway with my family present, multiple warning indicators activated simultaneously, including a blinking check engine light, traction control light, ESC warning, and a forward collision warning. Immediately thereafter, the vehicle experienced a rapid and significant loss of power accompanied by a loud and persistent engine knocking noise, rendering the vehicle unsafe to operate and placing the occupants at risk. It is important to emphasize that traction control and ESC systems are not causally related to an engine misfire condition, further supporting that this event was abrupt and not part of a progressive or diagnosable issue. A diagnostic scan performed at that time identified a misfire in cylinder 1. Upon delivery of the vehicle to the dealership for inspection, it was determined that the engine had suffered complete internal failure and was deemed “blown.” This finding confirms the occurrence of a catastrophic mechanical breakdown. Based on the sudden onset, absence of prior warning, and severity of the failure, there is no reasonable basis to attribute this condition to normal wear and tear, operator misuse, or neglect. Rather, the facts support the conclusion that this was the result of a latent defect or internal mechanical failure beyond the operator’s control. Accordingly, this matter should be addressed under applicable warranty coverage or consumer protection standards.

Filed Feb 28, 2026 · Transmission · MN

While driving my 2021 Chevrolet Tahoe at highway speeds (approximately 60 mph), the transmission suddenly malfunctioned due to what the dealership is telling was a valve body failure. Without warning, the vehicle lost proper propulsion and began to decelerate rapidly in active traffic. I did not receive adequate warning before the failure occurred. The sudden loss of power at highway speed created a very dangerous situation. Vehicles behind me had to brake abruptly, and I was nearly rear-ended. This presented a serious safety risk to me, my three children, and surrounding drivers. The issue was later diagnosed as a transmission valve body failure. A failure of this nature should not occur on a relatively new vehicle, and there Is currently a recall on other 2021 Tahoe’s for this same issues. My car is sitting at the Chevy dealership waiting for a full valve body replacement, which the dealership said they are having issues getting the part and will take over 2 weeks. The cost is around 5k to fix.

Filed Feb 23, 2026 · Engine · NY

My 2021 Chevrolet Tahoe engine seized while I was driving on the highway. All I heard was a loud clunk then there was a sudden power loss while I was driving before I could even get to the side of the road. I had to pay, out of pocket, to get a tow because the vehicle failed to crank or start. I had the vehicle towed to the Chevy dealership in Paramus, NJ just to find that this is a known recalled issued with the 5.3L, V8 engines which is the engine my vehicle has. There seem to be problems specifically regarding defective connecting rods or the crankshaft but for some strange reason my vehicle's vin number is not included in this recall although it is the same year, same vehicle, same engine and same problem. My vehicle should be included in the recall so it can be repaired for free at the chevy dealership in Paramus, NJ as I use this vehicle to transport children and that is very unsafe to have this defect and not fix it for free when it is not the fault of the driver.