2021 GMC Yukon XL engine problems

“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.”

“INCIDENT 2: Total Electrical / Power System Shutdown Component / System Failed: Electrical / Power Control System (Auto-Stop/Start System) Failure Description: Total loss of electrical power causing the main dashboard and display screen to go completely dark, stalling the vehicle during an autostop event at a traffic light and preventing the engine from restarting. Safety Risk: Sudden total electrical shutdown leaves the vehicle completely dead, unresponsive, and immobilized in active traffic lanes/intersections, creating a high risk of rear-end or multi-vehicle collisions. Dealer / Repair Shop Confirmation: Customer complaint and active fault codes confirmed by dealership service department following standard maintenance schedule. Warning Symptoms: Display screen went blank; failure occurred instantly during autostop/traffic light stop without prior warning. Inspection Availability: Vehicle and affected systems are available for inspection upon request. INCIDENT 3: Fuel Pump Driver Module (FPDM) Failure Component / System Failed: Fuel Pump Driver Module (FPDM - Part #13554821) / Engine Control Module (ECM) Communication Failure Description: Total loss of…”

“INCIDENT 3: Fuel Pump Driver Module (FPDM) Failure Component / System Failed: Fuel Pump Driver Module (FPDM - Part #13554821) / Engine Control Module (ECM) Communication Failure Description: Total loss of communication between the ECM and FPDM, causing the engine to abruptly die while idling at a traffic light. Subsequent attempt to restart using push-to-start produced a severe mechanical screeching noise. Safety Risk: Unexpected stall in active traffic left the vehicle stranded and unable to restart safely, exposing occupants to collision hazards. Dealer / Repair Shop Confirmation: Confirmed by Service Technician. Diagnostic Code P129F ("ECM lost communication with fuel pump driver module") logged; verified power and ground failures at the module. Replaced FPDM (Part #13554821). Warning Symptoms: None prior to failure. Sudden engine shutdown followed by screeching sound on attempted restart. Inspection Availability: Vehicle and replaced module are available for inspection upon request.”

“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”

“I own a 2021 GMC Yukon XL Denali equipped with the 6.2L L87 V8 engine (VIN: [XXX]). At approximately 149,000 miles, the engine developed a significant internal mechanical failure requiring complete replacement. The vehicle was diagnosed by Lexington Park Chevrolet Buick GMC, an authorized GM dealership in [XXX]. The technician identified a misfire in cylinder #5, significant oil contamination of the combustion chamber and spark plug, and broken oil-control rings on piston #5. The technician also documented bottom-end engine noise and determined that replacement of the engine assembly was necessary. The dealership replaced the engine with a GM remanufactured 6.2L L87 engine (part number 19420611), at an estimated cost of $10,950. Although my vehicle was not included in GM Safety Recall 25V-274 (N252494000), I am concerned that this significant internal engine failure may be relevant to NHTSA's ongoing investigation of L87 engine failures, particularly those occurring in vehicles outside the original recall population. I request that NHTSA review and document this failure as part of its ongoing evaluation of the L87 engine and the scope of the existing recall.”

“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.”