2016 GMC YUKON XL Complaints

1. My vehicle is having transmission issues with shuddering and shifting. M5U RPO code 8L90 transmission. 2. My safety and the safety of others is a concern if the transmission is not working as intended my vehicle could be at risk an accident that could be avoided. 3. The problem has not be reproduced or confirmed by a dealer I work on my own vehicles and I am going to repair this issue myself if able. 4. There are no trouble codes on my vehicle when scanned with an OBD2 scanner.

After my child had thrown up all over the car seat her father had taken her inside to clean up and I took the car seat apart to throw the pieces into the washer to clean them. The harness strap did not come out fully clean so I contacted Graco for a replacement piece and I was told that they don’t replace those and that the strap being removed totaled my car seat. It has a woven material tab that goes up through the hard plastic base and locks in by opening itself. It’s essentially a T in the material so it can be folded to go back through the hard plastic base. I was told that since the manual doesn’t provide instructions regarding that piece that I should know it’s not to be removed. No where in the manual, on the car seat or on the strap says it’s not to be removed. I did not damage/break/cut any pieces to get it in or out of the car seat. I was a mom in a panic trying to clean the car seat as quickly as possible so I could tend to my sick child. There were no warning signs telling me anywhere not to remove it. I don’t want other parents to do what I did and have a totaled car seat that they continue to use. I did not have the manual at the time of removing the pieces for cleaning but I have since located the PDF and read through all 96 pages.

My wife was driving down the highway and out of no where there was a loud taping sound, the vehicle started running real bad (skipping), the vehicle lost power and she lost control of the steering. As a result, she ran off the road into a ditch. this is a known concern with the 6.2 liter engines and all signs are pointing to lifter failure. She could have ben seriously injured and GM is responsible for this.

I am submitting this complaint to report what I believe to be a serious and systemic safety defect involving GM 6.2L engines equipped with fuel efficiency systems such as Active Fuel Management (AFM) or Dynamic Fuel Management (DFM). I have experienced catastrophic engine failure in two separate GMC Yukon Denali vehicles with nearly identical symptoms, which strongly suggests a broader design defect rather than isolated mechanical issues. My first vehicle, a 2015 GMC Yukon Denali XL, developed significant engine performance problems consistent with known lifter and camshaft failures widely reported in GM vehicles using these fuel efficiency systems. Due to ongoing reliability concerns and the financial burden of potential repair, I was forced to trade this vehicle at a loss. My second vehicle, a 2016 GMC Yukon Denali XL equipped with the same engine platform, suffered sudden and catastrophic engine failure in February 2026. This failure occurred abruptly and without meaningful prior warning, rendering the vehicle inoperable and creating a potentially hazardous situation. Sudden engine failure of this nature presents a significant safety risk, particularly if it occurs at highway speeds or in heavy traffic. An oil service had been performed on this vehicle in December 2025 at a Jiffy Lube franchise. After the failure, an independent service provider documented that the oil fill cap had been left loose. However, the Jiffy Lube franchise and its insurance carrier have denied responsibility, asserting that the engine failure is attributable to known defects and reliability issues associated with GM’s fuel efficiency engine systems. As a result, both the manufacturer and the service provider are denying responsibility for a catastrophic mechanical failure that has serious safety implications. This leaves consumers exposed to sudden engine failure risk with no meaningful recourse. Based on my direct experience with two separate vehicles exhibiting similar catastroph

I was test driving the vehicle after some and as I was test, driving it, the steering lot up on me. Luckily, I was entering a residential area when it occurred down the street from my residency; in which I was able to drive it to my residency, during that short ride, you could smell a burning smell coming out along with some crackling noises. I had to get the vehicle towed a week later to the mechanic shop where they fix one of my engine problems and verified that I needed a new power steering unit and gave me a quote, I couldn’t afford the word and started doing research and came across the recall for the power steering within my vehicle year, make and model. I replaced the power steering unit, but I’m having a difficult time celebrating the system..

My vehicle has been in 16 times since I bought it the most recent incident is for the engine which started about six months ago. It’s been in since then for other issues concurrently with this one it hesitates like it’s getting stuck in sand before it wants to go first the mechanic told me he didn’t sense it but the thermostat was stuck open so they fix that. Second time it went in they thought it was some sort of a filter and some other components I’m not sure. Again it was not fixed then my son and I were out in Minnesota freezing cold night in November and go and drive and then when again it was the drive train this time that got fixed a month ago about a week ago it starts making a noise like there’s too much snow in the tires. I get my car washed every few days but I got it washed again and that didn’t fix it so it’s in the shop again and I’m paying for a rental again. I have the Walser guard thank the Lord because it’s paid for itself about 15 times over. I’ve gotten two transmissions, an air conditioner, two sensors the arm that other people have complained about I don’t know exactly the name of it the trailer component that you plug into also blew out my seven way and I had to have my seven way wire fixed so I’m nervous about plugging that back in. My dad passed away and I spent $70,000 of my inheritance by this car. I should’ve flushed it down a toilet instead. Everybody makes fun at work that this car is literally gonna kill my kids and I because every other day it feels like we’re stuck on the side of the road.

Driving after dark on a main street in St George Utah, the engine suddenly surged and then revved down. It felt like someone jamming it into 4WD. Traffic was tailgating me, and I was nearly hit. I could not pull completely out of the right lane. I put on hazard lights. Check engine light came on, and TCS light came on. I decided to get out of traffic & crawled forward about 30 yards into a Sinclair station lot, then backed it into a spot where a tow truck could get it. It was clearly not drivable. Called AAA and a driver was able to get to me within 1/2 an hour. Checked the AAA website for mechanics since I was merely travelling through St. George and had no knowledge of the area. Hawker's Automotive was listed first, with many excellent reviews. Tow truck arrived and driver loaded it on the JerrDan bed. I asked him to take me to the Hawker's garage location. I locked it and put the key in the overnight box with my name, number, and description. Next day the mechanics said lifter arm was collapsed. Needed tearing down, replacing and probably new camshaft. Gave me estimate for "estimated" repair of about $8,000 or new engine at about $12,000! This is a KNOWN GMC failure apparently. Recalls have been initiated on newer models, but every mechanic will tell you that this happens all the time to all the 6.2L, V8 engine at around 150,000. I bought it used at about 156,000 miles and have put about 5,000 miles on it. And changed the oil at purchase, and about 1,000 miles ago. I researched model and year before purchasing. All online reviews I found were positive. Nothing out there on this know manufacturing flaw. But now when I type in 'catastrophic engine failure 2016 Denali XL" many many reviews and videos state that it is a known problem to both GMC and NHTSA. I or someone could have been killed by such a dramatic loss of power! This is a SAFETY issue and NHTSA needs to review ALL THE COMPLAINTS ON FILE ALREADY. Thankyou

There is a hesitation when trying to accelerate. The car will then slam forward and there is a rattling noise that the car also makes. This has almost caused accidents. I was driving in town which is where I do most of my driving.

The engine is the component that failed and is available for inspection. The issue has been confirmed by an independent service center, and the repair quote is attached. There were no prior warning signs before the failure; the vehicle suddenly began making a knocking noise and experienced a loss of power.

While driving vehicle the vehicle appears to shut off as if someone is turning off the ignition. The steering control becomes stiff, power is lost and electronics flash and turn off and on. This has happened on multiple occasions and is intermittent during acceleration. The accessible grounds have been checked, battery checked and replaced, and alternator checked and verified to be charging appropriately. Several codes are present and have been cleared to return indicating low voltage issues with multiple systems.