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Power Train, seat Belts, engine
01/22/2025
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 immed...
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Engine And Engine Cooling
06/14/2025
The contact owns a 2021 GMC Yukon. The vehicle was taken to the local dealer for a routine oil change. While driving, the oil low light illuminated. The vehicle was burning an excessive amount of oil. The local dealer was contacted again, but the vehicle was not diagnosed or repaired. The manufacturer was contacted, who referred to the local dealer. The failure mileage was approximately 149,000.
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Engine, fuel/propulsion System
04/28/2026
The vehicle suddenly began vibrating noticeably when idling and at low speeds. About 30 minutes after this started happening a warning lamp lit up. We drove the vehicle about 2 miles to a local auto parts store to get an initial computer diagnosis of the issue. The test resulted in a code of "P0304" which detected a cylinder #4 misfire and recommended a fuel injector replacement. We brought the vehicle to a local mechanic to get the issue further evaluated. After this evaluation, it was determined that the cylinder #4 misfire was related to a lifter failure. The mechanic explained that this situation could possibly have caused more damage, specifically to the camshaft, but that job was bigger than he was willing to take on. He recommended we get the vehicle towed to the dealership for further evaluation. He also informed us that this situation was common with the engine in this vehicle and GMC is aware of it. He directed us to some articles online that elaborated on the pote...
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Engine
05/05/2026
I took my GMC Yukon in for a recall. They changed the oil, programmed my module, changed the cap, and tested the engine, saying it was good. I took it on a trip, 7000 miles later engine locked up.
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Power Train, engine, fuel/propulsion System
04/28/2026
The vehicle drove normally earlier in the day with no major drivability concerns. Later, reverse gear suddenly stopped functioning and the engine would rev abnormally without the vehicle moving properly while in reverse. Shortly afterward, while driving, the vehicle displayed the warning message “Reduce Acceleration – Drive with Care” and began losing acceleration and propulsion. The vehicle would not accelerate normally and later could not exceed approximately 20-35 MPH. The condition created a significant safety concern due to sudden loss of acceleration and propulsion while operating in traffic. The engine RPM would increase abnormally while the vehicle failed to respond properly in drive and reverse. An independent mechanic inspected the transmission and found diagnostic trouble codes P0747, P0776, and P0700 related to transmission pressure control and valve body operation. Inspection also revealed significant metal contamination, sludge, and clutch material inside the transmissi...