GMC Yukon XL misfire problems

Filed Nov 7, 2026 · Engine · TX

I am filing this complaint against McKinney Buick GMC, located at [XXX]. I own a 2009 GMC Yukon XL. On XXX, I paid McKinney Buick GMC for repair services under Repair Order/Invoice #XXX. Following the dealership's service, my vehicle began experiencing serious mechanical problems, including engine misfires, rough and unstable idling, and jerking and shaking while slowing down. I became concerned that these problems could be related to the dealership's previous repair work. I returned the vehicle to McKinney Buick GMC and specifically requested that the dealership inspect the vehicle and investigate the problems. However, the dealership kept my vehicle for several days without performing the requested diagnostic inspection or making any repairs. I eventually had to retrieve my vehicle without the problem being resolved. I also requested a complimentary loaner vehicle or rental assistance while my vehicle was being held by the dealership, but my request was refused. I paid for the original repair service and expected the dealership to take responsibility for investigating problems that developed afterward. Instead, I was left without a resolution and had to take my vehicle back in the same unresolved condition. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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 · MD

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 the federal safety agency's ongoing investigation of L87 engine failures, particularly those occurring in vehicles outside the original recall population. I request that the federal safety agency review and document this failure as part of its ongoing evaluation of the L87 engine and the scope of the existing recall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 20, 2026 · Engine, Transmission · AZ

Truck has shuttered, rough idle since May 2026 after purchased new March 2026. We have been to two different GMC dealers who cannot duplicate the problem. Last week the truck started to shutter regularly after highway travel. When coming to a stop in traffic, the truck shutters to kill, loses power, RPMs drop below 500 and then recovers to a rough idle. Last evening Oct 20,2026 while driving the engine light came on, vehicle computer stated “ Issue with Engine / Transmission System Schedule service now.” This is the third time the vehicle will be at the GM dealer for diagnosis. Two times previous, dealer stated “unable to duplicate customer’s complaint.” We have owned this 2026 GMC truck for 8 months, purchased new and have nothing but issues which no GM dealer seems to be aware of nor can duplicate. This vehicle is unreliable and now has sat out of service awaiting a diagnosis for over 15 days at two different dealers. We have opened our second case with GMC Customer Care’s with zero assistance. It is the duty of a manufacturer to provide consumers with a safe and reliable vehicle. My 2026 GMC Yukon Denali is not safe and puts me and my family at risk of engine failure and a potential accident. We have documented every event and have videos of described defective vehicle operation.

Filed Oct 14, 2026 · Engine, Transmission · LA

On 9/11/26 the Yukon XL flashed a check engine light and message stated to service within 7 business days. 30 seconds later the power shut off and barely coasted to the side of the highway. Engine would turn over but not start. Could not shift into neutral b/c wouldn’t start. Error message: ECM - Engine and Transmission SystemP102AThe Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer.Service within 7 days Had vehicle towed to dealership. Was repaired and picked up on 9/25/26. Paid for new battery over $400.00 On 9/29/2026 Yukon XL would not shift into reverse. The error message on the car stated. TCM - Engine and Transmission SystemP2718. Odometer: 76117 Miles

Filed Sep 23, 2026 · Engine · CA

This is an ongoing problem from date of purchase, before the normal oil change time the low oil light comes on. When i check the oil dip stick it is in fact low. I have to add at least 2 qts of oil to get it to the right level. Time frame would be at least once every 2 months under normal CA driving conditions. Also does have a rough idle and noise that sounds like the motor is going to come apart on startup. I have takin it to the dealer, they performed consumption test and checked the motor recall. The dealer told us that our motor passed the recall inspection, made the changes, oil, oil cap, etc. Then told us it passed the consumption test. Since then I still have to add oil between oil changes. We were told by the service tech that even if the motor is bad, there is no replacements at this time and the vehicle would just sit at our dealership until we can get a replacement. No one has been hurt at this time. I'm just waiting for the motor to lock up. The vehicle can be inspected upon request. The only warning light that comes on is the low engine oil warning.

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 · 137,000 miles · NC

The contact owns a 2017 GMC Yukon XL. The contact stated that on several occasions while driving at various speeds, there was a loud ticking and tapping sound coming from the engine compartment. The vehicle was taken to two independent mechanics, where it was diagnosed and determined that there was a lifter failure caused by the AFM system and an engine misfire, and that the lifters, camshaft, and timing chain needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 137,000.

Filed Aug 31, 2026 · Engine · MI

After engine passed check for possible replacement because of recall, engine failed 5000 miles after. Even though I have a new engine now, there is no warranty coverage other than the lower part of the engine. I am already having misfire issues.