2021 GMC Yukon XL: sudden loss of power

Filed Nov 4, 2026 · Engine, Fuel system · MI

INCIDENT 1: Internal Engine Failure & Excessive Oil Consumption Component / System Failed: Engine Internal Components (Piston Rings, Valve Guide Seals, Spark Plugs) Failure Description: Excessive oil consumption (1.5 to 2.0 quarts burned every 2,000 miles) leading to heavy oil-fouling on spark plugs #5 and #7. Required complete cylinder head, oil pan, and piston teardown to replace all pistons, rings, connecting rod bearings, lifters, guides, valve guide seals, and spark plugs. Safety Risk: Severe internal engine oil consumption and plug fouling create an immediate risk of engine misfires, unexpected loss of power, or catastrophic engine failure while driving at highway speeds. Dealer / Repair Shop Confirmation: Confirmed by Dealership Service Department via oil consumption tests, spark plug inspection with oil dye, compression tests, cylinder leak-down tests, and physical teardown. Warning Symptoms: Low oil warning lamp illuminated; continuous need to top off oil between routine maintenance services. Inspection Availability: Vehicle and replaced components are available for inspection upon request.

Filed Nov 4, 2026 · Engine, Fuel system · MI

INCIDENT 4: Fuel Injector Internal Short (Cylinder #6) Component / System Failed: Fuel Injection System / Cylinder #6 Fuel Injector & Wiring Harness Failure Description: Cylinder 6 fuel injector failed due to an internal electrical short circuit, causing immediate engine misfires and severe power reduction. Repair required replacing the Bank 2 fuel rail, four fuel injectors, and the injector wiring harness. Safety Risk: Immediate engine shuddering and abrupt drop in drive power while operating in active traffic creates a serious loss-of-acceleration hazard and heightened risk of a rear-end collision. Dealer / Repair Shop Confirmation: Official diagnosis confirmed by Service Center Technician via electronic diagnostics verifying the internal electrical short circuit. Warning Symptoms: Check Engine Light illuminated simultaneously with engine shaking and sudden power loss; no prior symptoms existed before the failure. Inspection Availability: Confirmed via technician diagnostics; Check Engine light illuminated along with four other warning lights- car had to be towed to dealership to be fixed

Filed Nov 2, 2026 · Engine · 9,000 miles · TX

The contact owned a 2021 GMC Yukon XL. The contact stated that while driving 75 MPH, the vehicle suddenly shut off and lost power in the middle of traffic. The contact attempted to restart the vehicle, but the vehicle failed to restart. The contact stated that the emissions warning light and the drivetrain warning light were illuminated. The manufacturer was notified of the failure and offered to pay half of the cost of the engine repair. The vehicle was towed to a dealer, where it was diagnosed with lifter and rod failures. The contact stated that the manufacturer was aware of the 6.2L engine failures. The failure mileage was 9,000.

Filed Sep 30, 2026 · Transmission · IN

Rear wheel lock up for a slight second and then down shifted and revved way up to high RPM then went into reduced power. then slowed down and had to drive about 15 miles an hour. to shop mechanic.

Filed Sep 22, 2026 · Transmission · MO

While driving the vehicle on a roadtrip in Missouri, the engine lost power and had a flashing check engine light. Upon diagnosis by three different technicians, the 6.2L Engine needs replaced after only 123000 miles. The lifters and camshaft have failed. This is a known safety issue and numerous recalls have been implemented, but my high end Denali is mysteriously absent from the recall. This is unsafe and unsatisfactory.

Filed Sep 18, 2026 · Engine · MT

Vehicle has been consuming engine oil at a rate of approximately 1 quart per 500 miles. On XXX, owner added 1 quart of oil in [XXX], then drove a round trip to [XXX] and back (approx. 860 miles). On XXX at 55,329 miles — only 9 days and roughly 860 miles after that quart was added — an oil change was performed at an independent shop; the technician noted no oil was present on the dipstick prior to service. On XXX at 55,829 miles — exactly 500 miles later — the vehicle was taken to an authorized GMC dealership, and the dipstick again showed no oil prior to service. The dealer began the manufacturer's oil consumption test protocol, performing an oil and filter change and other maintenance. Within approximately 74 miles of this service (current mileage 55,903), the engine began making an audible knocking noise. Oil level was checked and confirmed full/normal, ruling out low oil as the cause. The knock has been intermittent — not present at cold idle start, but returning during driving conditions, raising concern about potential engine failure or loss of power while driving. They can not get it back in till XXX. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 23, 2026 · Acceleration, Engine · OH

Was driving the vehicle at 70 mph on the highway without any issues for several hours and suddenly the vehicle lost power and had no propulsion. It went into neutral automatically and the engine shut off while driving. Thankfully I was on a downward slope and could steer the vehicle off the very busy highway. Once safe, I tried to restart the car but the engine would not start or turn over. Roadside assistance came to help as well as a flatbed tow truck. It was taken to a nearby GMC dealer but it remains completely dead despite the battery being fully charged and all of the electronics working. No known error codes are showing up. It’s an L87 engine and was part of the GM recall. The recall work was completed in Nov 2025.

Filed Aug 21, 2026 · Electrical, Engine · IL

Driving on busy road when heard a squealing from the engine bay of the vehicle. Moments later the vehicle lost power. It was a very dangerous situation traveling approximately 45mph on a multi-lane road in urban St. Louis Missouri. There was not a check engine light prior. The vehicle had a recall performed per GMC instructions prior (this amounted to a different viscosity oil....). The breakdown stranded my family and I while on vacation in another city. The vehicle was towed to a local GMC dealership and was diagnosed as a seized engine related to the recall. The engine is scheduled to be replaced as no cost through GMC's extended service. They have not provided coverage for the towing, for the multiple ride shares needed to get around on vacation, for the rental car needed to get home, or a rental car to help us with day-to-day life during the estimated 6-8 weeks we will be waiting. My family was at risk, other motorists on the parkway were at risk. It was pure luck and quick thinking that saved injury or loss of life. It is completely unbelievable GMC is letting these vehicles be on the road for peoples safety and for the money people pay as a consumer.

Filed Aug 17, 2026 · Engine, Fuel system · IL

I am filing a safety complaint regarding my 2021 GMC Yukon. While driving on the highway during a long-distance trip from [XXX] to [XXX], my vehicle suddenly experienced a serious loss of power, drivability issues, and loss of propulsion. The vehicle began shaking violently, slowing down unexpectedly, and struggling to maintain speed while in active highway traffic at highway speeds. At the time of the incident, the vehicle displayed a warning message indicating “Conditions Not Correct for Shift” at approximately 127,506 miles. Shortly after, the vehicle set diagnostic trouble code P0011, which relates to the engine and transmission system not performing as expected and indicates an issue with the Variable Valve Timing (VVT) system affecting engine timing and performance. The vehicle also entered a reduced performance state, and I was advised through the vehicle’s warning system to reduce speed, avoid hard acceleration, and avoid heavy load conditions. Despite following these precautions, the vehicle continued to run poorly and became increasingly unsafe to operate in highway traffic. This created a serious and potentially life-threatening situation, as I was traveling in fast-moving traffic and the vehicle lost normal propulsion and stability. I had to carefully maneuver out of active traffic lanes to avoid a potential collision. The vehicle eventually required roadside assistance/towing due to its inability to operate normally. Diagnostic trouble codes and warning messages were present at the time of failure. After the incident, I checked my VIN through the federal safety agency recall system and discovered that my vehicle has three unrepaired safety recalls. Of particular concern is: the federal safety agency Recall Number: 25V274 GM Manufacturer Recall Number: N252494000 This recall involves certain GM vehicles equipped with the 6.2L V8 L87 engine and describes a manufacturing defect in the connecting rod and/or crankshaft components that may result in engine damag INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA),

Filed Jul 2, 2026 · Fuel system · MI

My 2021 GMC Yukon XL recently suffered a failure of its fuel pump control module. This occurred at just 44,000 miles, mere weeks after my manufacturer warranty expired in June of 2026. This issue goes far beyond a financial inconvenience or a matter of consumer reimbursement; it is a severe, life-threatening safety hazard that GM has failed to permanently resolve. My Experience: Sudden Power Loss While Towing The gravity of this part failure became clear during a recent drive. I configuration-matched this vehicle—a heavy-duty Yukon XL with a 6.2L engine and a 4x4 towing package—specifically for its capacity to safely haul heavy loads. While traveling with a trailer attached, the vehicle experienced a sudden, catastrophic loss of engine power. Without warning, the engine sputtered and died. Had this occurred on a steep incline, a blind curve, or in heavy highway traffic, a catastrophic multi-vehicle collision would have been entirely unavoidable. Critical Safety Hazards and Concerns •Inability to Maintain Speed, Loss of Vital Assist Systems, & Compounded Towing Risks Systemic Failure and Inadequate Remediation What makes this situation entirely unacceptable is that this specific vehicle was already subject to previous GM safety campaigns regarding this exact component (including Safety Recall #N212332040 and subsequent Emission Recall #N252516900). GM is fully aware that their supplier produced defective modules that are prone to premature internal short-circuits. Yet, their remediation strategy has been entirely inadequate. By managing this through piecemeal, phased rollouts and limited VIN inclusion lists, they are leaving dangerous vehicles on the road until the point of failure. Drivers are effectively acting as crash test dummies, waiting for their engines to die in dangerous environments before GM acknowledges that their specific VIN was fitted with the defective supplier part.

Filed Jul 1, 2026 · Engine, Transmission · KS

Issue Description: The vehicle experienced a failure of the Dynamic Fuel Management (DFM) system, resulting in a collapsed lifter. This caused a cylinder misfire and a sudden loss of engine power while driving at highway speeds. Safety Concern: While traveling at highway speeds, the sudden misfire and loss of power created a dangerous condition. The vehicle could not maintain speed or accelerate properly with surrounding traffic, significantly increasing the risk of a collision. Failure Details: The issue was diagnosed as a collapsed lifter related to the DFM system. This caused persistent misfiring, rough engine operation, and severe drivability issues. Repair Outcome: Due to the extent of internal engine damage caused by the lifter failure, the vehicle required complete engine replacement.

Filed Jun 6, 2026 · Engine, Seat belts · OR

While I was driving home from the grocery store with my 4 kids our 2021 GMC Yukon XL (5.3L V8 engine), the vehicle suffered a sudden, catastrophic mechanical engine failure without warning. The engine began violently shaking, lost major propulsion, and dropped into a severe misfire state when we were coming down the highway. This created an immediate safety hazard on the road, as I suddenly lost the ability to safely accelerate or maintain highway speeds while hauling my children.A certified technician diagnosed the issue as a complete failure of the active fuel management hydraulic valve lifters and bent pushrods, a known manufacturing defect explicitly documented in GM Technical Service Bulletin PIP5776F. The internal failure required a total engine teardown and valvetrain replacement, costing over $10,000 out of pocket.General Motors has failed to issue a safety recall for this specific 5.3L valvetrain defect, despite it causing unexpected engine stalls, severe power loss, and immediate traffic hazards for drivers. This defective component poses an ongoing safety risk to families and should be upgraded to a mandatory safety recall. I am afraid to drive it every time I get on the highway in fear it could shut down again.