2021 GMC Yukon XL: check engine light

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 Oct 14, 2026 · Engine · NC

High oil consumption, will have oil changed and days later need oil, catalyst converter failed causing what was said for the check engine light to come on, truck now has a shutter around 50 mph, my radio is in and out, and sometimes it sounds like a computer shutting down. It has been one thing after the next.

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 10, 2026 · Engine · CA

My 2021 GMC Yukon XL Denali with the 6.2L L87 V8 has experienced two significant lifter/valvetrain failures. The first occurred at approximately 6,500 miles and was repaired by a GMC dealer. That failure involved cylinder #4, including a collapsed/stuck lifter and bent pushrod. The current failure occurred at approximately 110,269 miles. The vehicle initially operated normally. While traveling about 10 mph and approaching a major thoroughfare, the engine suddenly began making a loud knocking noise and the vehicle began shaking violently. There were no warning lights or other symptoms beforehand. Three children were in the vehicle. When the driver attempted to accelerate, the vehicle failed to gain speed normally, and additional accelerator input made the knocking and shaking significantly worse. The check-engine light began flashing, and “Service ESC” and “Service Traction Control” warnings appeared, along with multiple other warning lights. The engine continued running. The driver made a U-turn before entering the major roadway and drove about 0.2 miles very slowly back home. An independent repair facility diagnosed P0305, cylinder #5 misfire. Moving the ignition coil and spark plug did not move the misfire, and the #5 spark plug was oil-soaked. A GMC dealer later confirmed a stuck lifter on cylinder #5 and advised that the failed lifter damaged the camshaft. My concern is the sudden loss of normal acceleration and severe engine malfunction without warning, especially because this same L87 engine previously suffered a major lifter failure at low mileage. I am asking the federal safety agency to determine whether repeated L87 lifter/valvetrain failures represent an additional safety-related defect or failure pattern.

Filed Sep 1, 2026 · Engine · IL

Our 2021 YukonXL started running rough and the check engine light came on. We took it to the shop the next day and was told there was complete lifter failure and that we need a new engine.

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 Jul 13, 2026 · Engine · 116,204 miles · AL

The contact owns a 2021 GMC Yukon XL. The contact stated that while driving 55 MPH, several unknown warning lights illuminated, and the check engine warning light started blinking. The contact pulled over and became aware that the vehicle was shaking. The vehicle was turned off and restarted; however, the failure persisted, with smoke coming from the vehicle. The vehicle was repaired under the federal safety agency Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING); but the repair failed to fix the vehicle. The vehicle was taken to the dealer, where it was diagnosed, and it was determined that the camshaft needed to be replaced and that cylinder #8 was damaged and had detached. The manufacturer was notified of the failure. The failure mileage was 116,204.

Filed Jul 7, 2026 · Engine · GA

This is from dealership “found customers concern of engine light is on and ticking noise found cylinder 4 lifters to be collapsed causing the exhaust gasses to be trapped in the cylinder causing the cylinder wall to dry out and leaving scratches on the cylinder wall recommend replacing motor due to this problem at this time”

Filed Jun 16, 2026 · Fuel system · 59,000 miles · MA

The contact owns a 2021 GMC Yukon XL. The contact stated that while starting the vehicle, the engine stalled and the vehicle failed to start. The check engine warning light was illuminated. The vehicle was towed to an independent mechanic, who determined that the fuel pump power control module needed to be replaced. The vehicle was not repaired. The contact related the failure to the federal safety agency Campaign Number: 21V739000 (Fuel System, Gasoline); however, the VIN was not included in the recall. The manufacturer was made aware of the failure and advised the contact to file a complaint with the federal safety agency Hotline. The failure mileage was approximately 59,000.

Filed Jun 12, 2026 · Acceleration, Engine · AR

Check engine light comes on and an alert says "acceleration reduced" dealer says the coolant control valve is bad but the engine never overheats but the fans are running max speed 100% of the time.

Filed Apr 26, 2026 · Engine · PA

On April 20th, 2025 while accelerating from a stop light, my vehicle (2021 GMC Yukon Denali XL, 6.2L V8) started making a ticking noise and the service engine light started flashing. I was within a few minutes of my house and limped my vehicle home. The next morning, I started it and it exhibited the same symptoms. I called my local GMC Dealer, Wright Buick GMC, and was advised to have the vehicle towed to them. It was towed to the dealership and within a few days I was advised that the engine needed replaced. I had heard a story that there was a pending recall, so I had hoped that this would resolve itself without a bill to me. unfortunately I was advised that there was no actual outcome on how to handle recalls, so if I wanted my vehicle back, I would have to pay the $11K for replacement as I was outside of my power train warranty (I had roughly 73,000 miles on my car). I have hoped for some resolution to include my vehicle in this recall but I have not yet received any word from GMC.

Filed Apr 13, 2026 · Transmission · 82,000 miles · OH

The contact owns a 2021 GMC Yukon XL. The contact stated that while driving approximately 55 MPH, the vehicle decelerated unintentionally and failed to accelerate above 35 MPH. The vehicle failed to respond when the accelerator pedal was depressed. The contact arrived at the residence and was able to coast into the driveway; however, the vehicle failed to drive forward or reverse. The check engine warning light was illuminated at the time of the failure, with the message “Reduce Acceleration - Drive with Care” displayed. The contact waited for a while and then attempted to move the vehicle, and the vehicle drove forward slowly, and while attempting to reverse(R), the engine revved abnormally but failed to respond. The gear shifter was shifted to drive, but the vehicle failed to respond, and the engine continued to rev until depressing the brake pedal. The vehicle was towed to the dealer, and the contact was informed that the valve body needed to be replaced. The vehicle was not repaired because the part was on back order. The contact researched and associated the failure with the federal safety agency Campaign Number: 24V797000 (Power Train). The manufacturer was informed of the failure, and it was confirmed that the VIN was not included in the federal safety agency Campaign Number: 24V797000 (Power Train), and it opened a case. The manufacturer referred the contact to the federal safety agency Hotline to report the failure. The failure mileage was approximately 82,000.