GMC Complaints

My engine has had continual random piston misfire issues, I have changed the spark plugs, fuel injectors, and cat converter. The vehicle has "dynamic fuel management" (DFM) where four of the cylinders turn off when the load on the engine is low and turn back on when the load is high. A mechanic reviewed the vehicle and determined that all eight cylinders are turning off while driving due to the DFM. When it misfires there is momentary loss of power that potentially puts others at risk. A dealership performed a repair per a Bulletin but the issue was not fixed. The mechanic indicated this is a software issue with the computer update per the Bulletin. I have installed a DFM disabler to prevent DFM from working, don't have misfires, but this is an engineering issue that GM hasn't/won't address.

Known issue and has been attributed to a manufacturing defct, but no recall- Leaking headlight caused damage to headlight- now turn signal and headlight do not work. Entire assembly needs to be replaced, GM / Extended Warranty Company will not cover, this safety part. Head light and turn signal were working on the way to the dealer, 1 month later when we picked it up - Right turn signal malfuction reading appeared on dash, headlight blinking and will not work. Picked up on Friday 1/30/25, and made an appointment for the following Wednesday to take it back in. Was told by dealer today that the replacement will not be covered and will cost $2100.00 to replace. This is a safety part and the truck can not be driven legally or safely without both headlights working.

The electric power steering motor stopped working while driving on the highway. The vehicle was almost impossible to control and almost caused me to enter the oncoming lane of traffic.

All lifters had to be replaced at 5,315 miles on 7/28/21 #7 Piston had to be replaced at 42,431 miles on 5/24/24 This vehicle has the 6.2 L V8 L87 engine that is part of NHTSA Investigation # PE25001 I am reaching the 5yr/50,000 mile drivetrain warranty and am concerned that this engine could have recurring problems.

Driving truck at highway speed and went to pass a group of slower vehicles on my right. I increased speed to 75 mph and the engine stopped and I had no acceleration. Engine would not shift into Neutral and would not restart. I coasted off to an exit ramp and the truck stopped in the middle of it blocking traffic for about an hour. Highway Patrol was on site to help direct traffic through the intersection of the off ramp and side road. We sat for approximately an hour before a tow truck could get us out of the intersection. The truck transmission was locked tight and the tow truck had to put the back wheel on skates to move it. I had to pay $175.00 to this tow truck company to move me approximately 200 yards to a local restaurant where we waited for the GMC provided tow service to arrive. GMC provided tow truck would only tow to nearest dealership which was in Weimer, TX. At the time of failure there was no warning. The truck just shut down making loud wining noises since the transmission was still in gear. This was an extremely stressful event and I was worried that someone was going to strike us at highway speed from the rear. Traffic was heavy that day on [XXX] heading [XXX] towards San Antonio and most left lane speeds were 75-80 mph and bumper to bumper traffic. The GMC Dealer in Weimer was very professional and inspected the engine on Dec 2nd notifying me that is was a total failure and would need to be replaced under warranty. The dealer had a new engine in hand within a few days and the truck was repaired with two weeks. I had a couple other issues with the OnStar system and the wireless after I picked up the truck and drive it home. I returned it to the dealer and proper parts were ordered to replace a bad control module that had failed during the engine failure. It took some additional time on my own after this was replaced to get my OnStar account back up and running correctly. This truck also had "tailgate drop" issues that the dealer fixed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMAT

The GM N242454440 “collision Rear Wheel Lock Up from Transmission Valve Failure” was performed. The recall rendered the electrical charging system inoperable. GM engineering has been working on the vehicle for more than one month and recently determined that the recall software does not work properly with all vehicles. My truck is being returned to me without the recall being performed. Accordingly the safety hazard associated with rear wheel lockup has not been addressed and cannot be addressed at this time. Presumably GM will develop software in the future to address the safety condition. Meanwhile the safety hazard remains unaddressed for my vehicle and an unknown number others. Reference Riverview Chevrolet GMC repair order 894074

Nothing has happened so far but I believe they have an issue with the Allison transmission. When you first start off in the morning driving slow the transmission shifts hard with a thump. I've taken it in to the GMC dealership in Ft. Walton Beach, Florida and they kept the truck overnight and said everything seems to work as it should. I just traded my 2021 gmc 3500hd dually with 130k miles on it and never heard that or ever had an issue so I'm not sure what changed since then? I'm not sure what you guys can do to look into it? Thank you [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Oil consumption rate was too high, roughly 2qts every 1500miles. Caused timing chain to break. Second time with the oil consumption. First fix under 100k mile warranty checked off as recall. It was done before a recall came out. Paying for timing chain to get fixed but recommended a new engine. Prefer GMC to replace engine since it's an ongoing issue. 307373 miles strong and now this.

When pressing brakes to start the car the pedal goes all the way to the floor with little or no resistance. It has happened three times in 3 months. Took it to GM dealer after the first two incidents and they did a software update. Took it in again after the third incident and they did nothing.

While driving, vehicle threw an error “ reduced acceleration, drive with care”. I had my children in the car when the car abruptly reduced speed and car jerked. It was very scary while driving. It was stuck in 5th gear. I was taken to dealership. Code showed it needs a Transmission Valve Body replacement. Part # 24065353. Dealership has stated part is “on backorder with no ETA of the part”. My car has been sitting on the lot for 17 days waiting to be fixed.