2021 GMC Sierra owner complaints

Faulty lifters replaced on passenger side. Had only 25000 miles on engine. GM extended warranty on thousands with this engine but not mine. Have only 28000 miles on truck and just turned 5th year so warranty is void. GM should extend warranty on all vehicles with this engine.

Traveling on interstate going at the posted speed limit and turned off the interstate onto my exit turn and vehicle engine started knocking and engine shut off oil warning light came on all while trying to stop the vehicle at the cross traffice stop sighn and ended up stopped in the middle of another highway barley missing the cross traffic coming at me from both directions. This happened at i94 and county highway 34 at barnesville minnesota exit. This sudden engine failure nearly killed me and the 2 vehicle drivers that nearly struck my truck from both directions. GMC would not help me with my repair of over $11000.00 dollars for a new crate motor from GMC. Siting my truck did not fall under the l87 recall. Failure rod bearings and crank bearings with a ton metal shavings in the oil and f

Famous lifter issue in the l84 engine. Hundreds of documented complaints and current class action lawsuit. I had to stop on a busy highway and it caused unsafe passing and irritated humans.

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 15 MPH and making a turn, the vehicle lost power steering assist functionality. Additionally, the brake pedal was depressed several times but failed to respond. The parking brake, traction control, brake, engine, and headlights warning lights were illuminated. The contact also stated that the warning message "Limited Power" was displayed. The contact stated that he depressed the brake pedal with his two feet from a standing position and the vehicle decelerated and he pulled into a driveway. The contact was able to continue to drive the vehicle. The vehicle was taken to the dealer who diagnosed that the vehicle software needed to be updated. The contact stated that the vehicle was repaired. The manufacturer was not no

mechanical and electrical issues with my GMC Sierra Elevation Duramax Diesel, purchased in 2021. Despite multiple dealership visits, diagnostic evaluations, repairs, and software updates, these issues persist and have significantly impacted the reliability and safety of the vehicle. In December 2025, my vehicle was taken to the dealership for diagnostics and a third software update intended to resolve recurring engine-related faults. Throughout 2025, the check engine light illuminated on approximately 30 occasions, confirmed by at-home diagnostic scans. The same diagnostic code related to the 1) SCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 2 P2C7A - Engine I 2) Exhaust Gas Recirculation (EGR) Cooler Efficiency Below Threshold P14D9 - Engine has appeared repeatedl

15000 miles lifter failure in traffic highway at speed 70 MPH lost power engine failed multilane highway rush hour traffic no warning failure

The vehicle was bought brand new and was only driven for a week. It was in motion on the freeway when the engine started to sound noisier than usual, like that of an older truck. It was hard to notice on higher speeds on the freeway, but upon slowing down on curves, it got more obvious that something was really wrong because the noise sounded like something was loose inside the engine. There was no 'check engine' light or any other warning lights. Upon exiting the freeway, the engine shut off completely while in motion. Fortunately, I was able to pull in a parking lot and park it safely. The engine would not start safely after that, and 'check engine' activated. The vehicle is currently being diagnosed at a dealership. Last update was that the engine was being taken apart complete

The contact owns a 2021 GMC Sierra 1500. The contact stated that after the vehicle was taken to a local car wash, upon further inspection, the tailgate door had independently unlatched and was open. No warning light was illuminated. In addition, the contact stated that while driving at an undisclosed speed, the local Police Department called about luggage found on the side of the road. Upon further inspection, the contact noticed that the tailgate had independently unlatched and was open. The vehicle was previously taken to a local dealer, where the vehicle was repaired under warranty. The vehicle was taken back to the same local dealer where it was repaired for a tailgate switch failure at the owner's expense. The manufacturer was made aware of the failure. The failure mileage was approxi

The coolant control valve has failed on two occasions—once during the warranty period and again approximately 18 months later, outside of warranty. Each failure resulted in continuous fan operation and fluctuating engine temperatures. Failed on around June 2024 and again December 17, 2025

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 40 MPH, the message that the tailgate was opened was displayed, and the contact became aware that the tailgate had opened. The contact pulled over to the right side of the road to close the tailgate. The vehicle was not taken to an independent mechanic or dealer to be diagnosed or repaired. The contact stated that the VIN was not included in NHTSA Campaign Number: 24V060000 (LATCHES/LOCKS/LINKAGES). The manufacturer was notified of the failure and opened a case and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was 41,000.

I have a 2021 GC Sierra 1500, The guidance lines in the display when in reverse go from non-existent to barely visible and are not usable especially in sunlight. The service man at Miller Chevrolet in Marianna Fla says GMC is aware of the problem, that it was caused by the last update download and will be fixed by another download to correct the problem. He also says the same issue is nationwide and all trucks have the issue which I find hard to believe. 1.If that were true it would be a simple matter of a few lines of code to correct the problem. 2. I have been chasing this problem since October and have now made four trips to the dealership. 3. I cannot believe all trucks have this issue and also I suspect the same backup system is in all GMC vehicles regardless of type. 4. I cannot

Transmission valvebody failure, causing rapid, repeated rear wheel lock ups. Videos can be provided. These happen almost daily at highway speeds. This will cause a very bad accident

I received a notice of a recall for a known problem with GMC transmissions. it is very well known that these transmissions lock up and cause problems with braking and can cause the vehicle to slide off the road when the tires lock up. it also causes hard shifting, which I have experienced. GMC said they will not fix the transmission, they instead will add a device to monitor the transmission, so when the transmission locks up and causes an accident, it will let me know that it was the transmissions fault!!! How is this legal? they will let me know that their transmission caused the accident after the fact? why not fix it? typical of government to do nothing about safety... and instead make laws that allow big corporations and government to make money off of peoples deaths!

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds and downshifting, the rear wheels locked up with the parking brake warning light flashed on the instrument panel. The vehicle would resume normal operation soon after the failure. The vehicle was taken to a dealer where the contact was informed that there was a pending NHTSA Campaign Number: 24V797000 (Power Train) on the vehicle for the failure. The contact was informed that there was a temporary fix on the vehicle to repair the defect. After the temporary fix was performed, the contact experienced the failure twice within a week. The contact received a call that the permanent fix was available; however, soon after the repair was performed, the failure immediately occurred upon leaving the dealer.

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 24V797000 (POWER TRAIN); however, the part to do the recall repair was unavailable. The local dealer was contacted, and it was confirmed that the part was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact stated that the transmission was shifting hard while driving. The local dealer was notified of the failure. The cause of the failure was not yet determined. The manufacturer was not made aware of the issue. The failure mileage was 120,000. VIN tool confirms parts not available.

The Intermediate speed sensor 2 and internal transmission harness failed. The repair was to replace the internal transmission harness and intermediate speed sensor. This vehicle is a 2021 and I was told this was recalled on a 2022 only.

my truck keeps having this same issue since [XXX], always take it to team Gillman second august 26 same reason they replaced the battery but is a manufacturing defect while i am driving stops out of sudden AND THIS IS THE THIRD TIME THEY SUPPOSED TO CALL ME I HAVENT RECEIVE NO CALL IS AT TEAM GILLMAN SAME REASON ONLY HAS 18000 MILES MY NAME IS [XXX] CELL [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds, the tailgate opened unintendedly. No warning light was illuminated. The vehicle was taken to the dealer but was not diagnosed or repaired. The dealer informed the contact that the VIN was not included in GM Campaign Number: N232426401. The manufacturer was not notified of the failure. The failure mileage was approximately 57,000.

The power steering on the truck would quit working at times. I made an appointment with a local dealership to have it checked out. I was told the steering rack was binding and would need to be replaced. I was also told there was a two to four week backorder on the parts. As I am trying to back out of my garage to take it to the dealer the steering totally locked up. I called a wrecker to take the truck to the dealer the next day. When the wrecker operator started to load the truck, at first the steering wheel wouldn't turn . Then it broke lose and worked fine. Imagine if I were driving when this on again off again power steering would quit working!! I should also say this truck only has fifty-seven thousand miles on it. Since there is a backorder on these parts it tells me that I'm n