GMC Sierra Complaints (2021)

671 consumer complaints on file.

#11759956August 27, 2026
ELECTRICAL SYSTEM
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 25 MPH near the residence with the contact's daughter as a passenger, the vehicle experienced a complete loss of motive power when depressing the accelerator pedal. Several unspecified warning lights illuminated. The contact and the passenger pushed the vehicle to the residence. The vehicle was towed to an independent mechanic, where it was diagnosed that the electrical system experienced a severe power loss and the electrical modules were damaged. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 89,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11759357August 25, 2026
ENGINE
While driving down an isolated 2 lane road in West Texas, the engine in my 2021 GMC Sierra 1500 began making knocking sounds and vibrating badly. The truck's acceleration was extremely sluggish and the vibration worsened at slow speeds. I was able to slowly make my way back towards a dealership, where the diagnostic teardown revealed a bent pushrod and camshaft damage.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11759464August 25, 2026
POWER TRAIN, ENGINE
For close to one year, there feels like a catch, grind, stall, or slight shake, mostly while the vehicle is shifting gears, made worse or noticed more by higher speeds like driving on the highway vs. slow city streets. It's difficult to explain or assess so not sure if it is the engine or transmission. With the open recall from GMC on some vehicles with the same engine as mine it is concerning that maybe it should have been included.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11758686August 22, 2026
ENGINE
1. What component or system failed or malfunctioned, and is it available for inspection upon request? The engine oil consumption system/engine is experiencing excessive oil consumption. My 2021 GMC Sierra is equipped with the 6.2L engine, and the engine is consuming oil at a rate that I believe is abnormally high. The vehicle and engine are available for inspection upon request. I am also concerned that my vehicle may be affected by an engine-related recall or safety campaign associated with this engine. When attempting to verify the recall status, the system appears to have an error and is not identifying my vehicle. I am requesting that the vehicle’s VIN and engine configuration be manually verified against all applicable recalls and safety campaigns. 2. How was your safety or the safety of others put at risk? The excessive oil consumption creates a potential safety concern because I am concerned that the engine could become critically low on oil while I am driving, potentially resulting in engine damage, loss of power, or complete engine failure. This could occur while traveling at highway speeds or in an area where it may be difficult or unsafe to stop. I regularly travel with my family, which increases my concern about the possibility of an unexpected engine failure and the potential risk to my passengers and other motorists. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. I previously addressed this issue with Newton Chevrolet in [XXX], and later took the vehicle to Malcolm Chevrolet in [XXX], after continuing to experience concerns about excessive oil consumption. Malcolm Chevrolet tested the vehicle and confirmed that it is consuming oil at an excessive rate. The prior visit to Newton Chevrolet and the subsequent confirmation by Malcolm Chevrolet demonstrate that this concern has been reported and evaluated by more than one dealership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11758744August 22, 2026
ENGINE
While driving my son to school we were driving 45 mph and the entire engine shut off and lost all power. Engine would not restart. Took it to the dealer and was told the engine was dead.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11758633August 21, 2026
ENGINE
I purchased this truck from a used car dealer. It had received the fix in January this year. They sold it to me I put 15,000.00 down and financed 15,000.00. I had the truck two weeks and was driving down the road to pick up some tools from a friends. I pulled from a drive way I heard a pop likei hit something In The road nothing was in the drive or road I could have hit. I made it two stop signs to make the turn too go pick up the tools and as I am slowing down to stop the stuck shuts off at like 45 miles an hour and leaves me comming to a stop with a truck crank crank crank no start. Cause it said shift I to neutral to restart. I did and the engine went to cranking over and o er really fast. And I was Abel to get control and get stopped at stop sign blocking the stop sign and a guy with a boat behind me. My friend came with his truck and pulled me from intersection up into His yard. And I had car lot I bought it from come get it they tried to finance me a motor thru there prefers dealer. I went to them they explained that the cams and timing chain was staying still as they turned the engine Over by hand. The timing chain stayed staionary. I researched the truck online figured out there is a l87 recall and had it taken to dealer they are offering good will payment on labor because it is 6, 000 miles past the 150000 dead line Wich I only placed just over a thousand of the 156000 miles on this truck. I have been without this truck for 31 days as of today. And I feel they should replace entire engine. I Am so frustrated with this cause I already payed 15000 and don’t have the money to fix this truck.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756772August 13, 2026
STRUCTURE:BODY
rear sliding window has plastic body seam that is broken allowing water to leak into the truck and cause mold and rust
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756392August 12, 2026
ENGINE
2021 6.2L GMC Sierra Denali. Has the L87 engine that is recalled but yet my truck doesn’t fall under the recall although the recall is for 2021-2024 engines. Everything that the engine recall states is the issue with my truck, I have service report from dealership stating that there is wear/breakage of cam shaft/crank shaft amongst other things including cylinder 3 and 5 misfiring , bearings broken , filings in the oil , banging in the engine and safety lights on. My local GMC dealership recommended that the only acceptable action was to replace the engine at my cost of course. This is unacceptable of a supposed reputable large corporation not caring about the “little guy”. The truck only has 136000 kms on it and I was only going 60 km/hr when this happened. Please help as I feel GM knows this engine is faulty but somehow has managed to escape a recall on my vin number
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756397August 12, 2026
VEHICLE SPEED CONTROL
Push on accelerator truck barely would go, shifted hard, codes check engine lights flashing, engine sounded bad
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756447August 12, 2026
POWER TRAIN
Transmission Valve Body failure. - Caused wheels to lockup momentarily and killed the engine with sudden loss of propulsion. Link to video of incident: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756237August 11, 2026
VISIBILITY/WIPER
A small drip started approximately 18 months ago from top middle of left side window in rear slider. It was first mistaken as blow by from car wash. Leaking slowly progressed to dripping down middle of both side windows in rear sliders. Leaking progressed to drops coming from under headliner then dropping on side portions of rear slider. It then would drip onto seat or behind seats. Leakage was consistent with TSB 18-NA-383 as well as 20-NA-142 and 24-NA-103. In discussing with dealership, they recommended likely microfractures and sealant process called for in bulletins would likely resolve matter. As due diligence, spoke with independent glass shop to confirm. Glass shop indicated would not know until physically checked cracks/source of leak and looked for damage but based upon photos it appeared to be several frame fractures consistent with bulletins. I arranged rear slider replacement through independent shop. Upon pulling OEM slider, numerous stress cracks and fractures were noted. These included stain marks from water intrusion. Photos included showing original leaking as well as sample of cracks in original OEM plastic frame portion.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11754985August 5, 2026
POWER TRAIN
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission was shuddering, especially while driving uphill. The dealer was contacted, and the vehicle was diagnosed and determined to have a failure associated with a GM TSB for the incorrect transmission fluid inside the transmission reservoir. The vehicle was not yet repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 38,875.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755097August 5, 2026
SERVICE BRAKES
The left rear internal "top-hat" parking brake shoes suffered a total manufacturing bonding failure, causing the friction lining to completely delaminate and detach from the metal backing plates inside the rotor hub. This triggered Diagnostic Trouble Code (DTC) C060B (Left Park Brake Actuator Circuit). The failed components were replaced by the servicing facility and are unavailable, but the official dealer diagnostic scan sheet and itemized repair invoice are preserved and available for inspection upon request. Safety was compromised in two ways. First, the mechanical failure completely disabled the electronic parking brake system, forcing a heavy-duty truck to rely exclusively on the transmission's parking pawl to remain stationary. This creates a severe rolling vehicle hazard, especially on inclines or when hauling/towing heavy loads. Second, when these shoes disintegrate, the loose friction debris trapped inside the enclosed drum can shift, wedge, and cause a sudden mechanical wheel lockup or severe brake dragging at highway speeds, threatening vehicle control. The problem was officially confirmed and diagnosed by an authorized General Motors dealership service center. The technician scanned the vehicle, retrieved DTC code C060B, and confirmed upon inspection that the internal parking brake shoes had completely disintegrated. There were absolutely no physical symptoms, abnormal noises, dragging sensations, or brake pedal changes prior to the failure, as the parking brake shoes sit isolated inside the rotor hub. The issue appeared suddenly on May 23, 2026, when the vehicle immediately displayed a parking brake malfunction warning lamp on the instrument cluster dashboard and completely refused to engage the electronic parking brake.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753912July 31, 2026
ENGINE
P1010 and P2B86 engine code, constant cooling fan on engine. Confirmed by dealership, quoted for coolant control valve. VIN not included in special coverage N252508341 for this known issue. Limited engine power alert, unable to maintain speed on highway. Dangerous condition traveling under speed limit.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753949July 31, 2026
ENGINE
Engine temp rises way above mid-level and will stay there for several minutes before cooling back down to normal temps. 2 different mechanic shops have told me it's the coolant control valve, but want $2500 to fix it. This service bulletin is for the same year, make, model, and motor as my truck, but the dealership said it wasn't covered.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753689July 30, 2026
FUEL/PROPULSION SYSTEM
After finishing a long drive south, I shut the engine off and a yellow engine code popped on. I connected my computer to it and revealed a P129F code (fuel pump control module). I have noticed that other GMC models have been included in a recall concerning this problem. The 2021 GMC 2500 Denali should be also since it is the same problem. This needs to be covered by the manufacturer since it is a constant problem.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753693July 30, 2026
ENGINE, POWER TRAIN
2021 Harley Davidson Sierra 4WD, 6.2L L87. Started the truck in the morning and immediately heard intermittent, very loud banging noise coming from engine. Shut truck down quickly and had it towed to dealer. Diagnosis was bent pushrods & failed lifters which were replaced under warranty. Factory warranty expired only 4 months after this failure, and the recall does not include my VIN so I did not get an extended warranty or any other protection. GM has yet to even reimburse the tow bill. Completely unacceptable for a truck that was well over $100k when new.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753444July 29, 2026
ENGINE AND ENGINE COOLING
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 70 MPH, the vehicle suddenly lost motive power, decelerated, and failed to properly accelerate while depressing the accelerator pedal. The check engine warning light was illuminated. After exiting the freeway, the vehicle stalled. The vehicle was towed to the residence and then later towed to the dealer for assistance. The contact was informed that there were metal shavings inside the engine oil. The contact was informed that the engine needed to be replaced. The vehicle was not yet repaired. The contact was informed that the VIN was not included in NHTSA Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING). The contact stated that the vehicle had experienced the failure listed in the recall. The manufacturer was not yet contacted. The failure mileage was 149,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753543July 29, 2026
ENGINE, FUEL/PROPULSION SYSTEM
CORRODED GROUNDING STRAP FAILED CYLINDER 5 GLOW PLUG CIRCUIT CRACKED AND SEPARATED EXHAUST BACKPRESSURE VALVE
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11753048July 27, 2026
ENGINE
The vehicle has about 38000. The warrantee expired about 6 months ago. About three weeks ago I started the engine, it sounded like a cement mixer filled with rocks. I had it taken to my dealer. They investigated the problem and determined that it has bad lifters and bent push rods. The dealer told me that it is a known problem but it is not covered by the current 6.2l engine recall
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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