2021 Chevrolet Tahoe

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.

On [XXX], while driving near Mammoth Mountain, California (Highway [XXX]), the vehicle suffered a sudden, severe engine malfunction. The engine began misfiring violently, accompanied by a loud, mechanical clacking noise, and experienced an immediate loss of propulsion power. This mechanical failure left my family—including young children—completely stranded on the side of a mountain highway in a secluded wilderness area with dropping temperatures (39°F) and active local wildlife Because the vehicle could not safely maintain highway speeds or generate sufficient power, it created an immediate and severe traffic safety hazard, forcing us to secure emergency transport for the vehicle. Which took 4hours for someone to come out to the secluded hwy on a holiday weekend. Dealership Diagnostic Findings A formal inspection conducted by a certified General Motors dealership (Michael Hohl Motor Company) confirmed the following: Symptoms: Gas engine diagnostic confirmed "Misfire, and clacking noises coming from passenger side of the motor." Diagnosis: Cylinder Head / Valve / Lifter / Lash Adjuster failure. The dealership documented a collapsed lifter and recommended a complete engine tear-down to inspect lifters and pushrods for wear or bending. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

On September 19, 2026, while traveling approximately 30 mph, the vehicle experienced a sudden, hard shift. The check-engine light then illuminated. I pulled over as soon as it was safe to do so. After stopping, the vehicle would not shift into reverse and entered limp mode. The transmission malfunction created a safety risk because the vehicle’s operation and available gears became restricted unexpectedly while it was being driven. The loss of reverse also prevented the vehicle from being maneuvered normally. The vehicle was not driven after the incident and was towed from the location. The vehicle and affected components are available for inspection upon request. At this time, the vehicle is awaiting inspection and diagnosis to determine the exact cause of the transmission malfunction.

2021 Chevrolet Tahoe – Unexpected Shutdown/Restart While Stopped On two separate occasions, my 2021 Chevrolet Tahoe has unexpectedly appeared to shut down while I was stopped with my foot on the brake. The vehicle is equipped with Auto Stop/Start, and initially the event seems like a normal Auto Stop. However, instead of a normal engine Auto Stop/Start cycle, the vehicle appears to shut down or reset more completely. The event is jarring, and the power door locks lock/unlock as the vehicle shuts down and restarts. The vehicle subsequently restarts and I have been able to continue driving. This has now occurred twice while stopped. I am concerned that the vehicle may be experiencing an unintended stall, loss of electrical power, or another malfunction rather than normal Auto Stop/Start operation. I checked my VIN through NHTSA and it does not currently show an open recall. I am aware that certain 2021 Chevrolet Tahoes have previously been recalled for a condition that could result in an engine stall, although my VIN does not appear to be included in that recall population.

I received an automated message from the vehicle stating to service the safety restraint system. I took the car to the local dealer and they ran a diagnostic review. There is a TSB for the vehicle and they say that the problem is coming from the overhead console part number 86575239. This part is not available anywhere. I contacted General Motors and requested assistance. All they have done is escalate it to the parts delay team. When I called today, all they say is they do not have any information available. They can’t even say when the part will be in stock. The dealership was unable to say that the airbag system would work as required or not. The car is unusable due to the passenger air bag system fault.

The number 7 DFM lifter failed and is suspected of failing due to the Active Fuel System. The vehicle is currently at the dealership where it was diagnosed and is awaiting replacement parts that are on GMC back order for a month or longer. The vehicle started shaking on 8/25/26 when idle and the following warning lights were visible: AVS, traction control, and ECU.

DFM (Dynamic Fuel Management) system failure causing collapsed lifters, oil consumption, and complete engine failure. To repair our vehicle it will require a complete engine replacement. This has been a known issue with GM and yet there has been no recall to fix the issue. Now our engine must be replaced.

Total engine failure. No warning lights shown and vehicle had been checked numerous times and reported as just fine.