Complaint volume
487 consumer-submitted complaints are matched to this model year. Treat the count as a research signal, then read the actual summaries for repeated symptoms.
Complaint records
2021 GMC Sierra Complaints
487 consumer-submitted complaints on record for the 2021 GMC Sierra, grouped by component category.
487 Total complaints
5 Crash reports
6 Fire reports
2 Injury reports
Complaint data reflects consumer-submitted reports. A complaint is not proof
of a defect, recall, or manufacturer fault. Enriched severity fields come
from official bulk records when the complaint can be matched by ODI number.
Buyer interpretation
How to use these complaints before buying
Complaint records are most useful when they turn into inspection points, seller questions, and comparison checks against nearby model years.
Pattern to inspect
The most common categories are engine, power train, engine and engine cooling. Use those categories as a test-drive checklist instead of judging the vehicle from the total count alone.
Severity flags
Enriched records include 5 crash reports, 6 fire reports, 2 injury reports, and 0 fatality reports. These fields come from complaint records and should be read in context.
Mileage clue
Mileage is available on 104 complaints, with an average reported failure mileage of 51,093 miles. Compare that with the mileage on the listing.
Questions to ask the seller
- Have you had any problems related to engine, power train, engine and engine cooling?
- Can I see recent maintenance and repair records?
- Has the vehicle ever been towed, involved in a crash, or repaired for the same issue twice?
- Can we also check the recall record for this 2021 GMC Sierra?
Used-car checklist
Use these complaints before the test drive.
Build a buyer checklist to turn these issues into questions and inspection points.
2021 GMC Sierra
Build buyer checklist Compare with other years Sends year, make, and model to pre-fill your checklist.
How severe are the 2021 GMC Sierra complaints?
5 Crash
6 Fire
2 Injury
0 Fatality
30 Towed
3 Medical attention
What are the most common 2021 GMC Sierra complaint categories?
ENGINE 156
POWER TRAIN 59
ENGINE AND ENGINE COOLING 37
POWER TRAIN,ENGINE 29
ELECTRICAL SYSTEM 26
UNKNOWN OR OTHER 14
STEERING 13
UNKNOWN OR OTHER,ENGINE 12
ELECTRICAL SYSTEM,ENGINE 9
SERVICE BRAKES 9
487 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Apr 2026 | POWER TRAIN,ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 45 MPH, the transmission inadvertently shifted from drive (D) to first gear. The check engine warning light was illuminated. The vehicle was pulled over to the side of the road and then towed to the dealer, where it was diagnosed, and it was determined that the valve body needed to be replaced. The vehicle was not repaired because parts were not available. The manufacturer was notified of the failure. The failure mileage was approximately 103,000. | Crash: No Fire: No Towed | 103,000 |
| Apr 2026 | ENGINE AND ENGINE COOLING | See attached document for complaint. INFORMATION, DETAILS, COMMENTS, DATES, AND NUMBERS ON RECALL 20211500 DENALI Recall Vehicle Information: All models of GM's with 6.2L gas engine (My personal truck I owned} • Recall date: April 23, 2025 650,000 + GM vehicles with 6.2L gas engine, years 2019-2023 • Manufacturer Recall Number: N2524944000 (letter issued by State of Washington Dept. of Licensing, PO Box 9020 Olympia, WA. 98507-9020 • NHTSA Recall Number: 25V274 • 2021 GMC 1500 Sierra Denali, x-tended cab, 4wh dr, 6.2 L gas engine • Vin #: WITH 6,400 MILES ON MY TRUCK May 15, 2025 • Went to local dealer, Becker Buick-GMC in Spokane, WA., to verify there was a recall on my truck and vin. #. Confirmed with there service department and sales person Jon Stone. • I was informed that the Dealership, service dept., and salesman Jon Stone, and Sales Mgr. Cameron could only say the following: "GMC DOES NOT have the tools made yet to verify if the engine will need to be replaced and would add me too the list and keep me posted." • I was informed at this time that t he issues with the engine were: engine could stop and start again at random; the engine start to smoke and stop; the engine could catch fi re whether it was running or not, or the engine could do ALL THREE things. • I was told to just keep driving the truck but watch for any of these issues. May 28, 2025 • Stopped in local dealer, Becker Buick-GMC, again to see if any updates. • Told GMC still had done nothing to develop the necessary tools to evaluate the engine and had no date to report or share with me on when they co uld. • Again, I was told to keep driving the truck and if I had a problem, Becker Buick would come and tow me. • Salespeople did ask if I wanted to just buy a new truck several times. They were impressed my truck only had 6400 miles on it and in such excellent shape. This was to be my retirement truck. June 5, 6, 7, 2025 • I visited several car dealers in the Spokane, WA. Area. Ford, Chevy, Dodge and Toyota. While looking at new/different vehicles to buy/trade I got much the same responses. "Sorry, we CAN" TTAKE YOUR TRUCK IN TRADE, until GM releases it off the recall list and states it is repaired. Everyone was aware of this massive recall by GM. June 18, 2025 • Not getting ANY ANSWERS, I called GMC Customer Service at 800.462.8782 and spoke with Cust. Service Manager, Brandy. • After long conversations, Brandy informed me that the tool(s) to check and evaluate the engine had NOT been developed yet and she could not give me a time line as to when that would be. She further confirmed that NO DEALER in the USA had the tools yet, even after I volunteered to drive to one. • I then said what I was wanting at this point, as their GMC dealer (Becker Buick) had told me to keep driving the truck, was I wanted either a long block engine replacement at NO CHARGE or at minimum and extended warranty of 125,000 miles on the complete engine and running gear. • I was informed by her that she could not honor either, and that any of her managers would tell me that I had to work directly with my local dealer. She offered no other solutions or advice, other then GMC would keep all the dealers updated on the tools, actions, and results. • I asked for the phone info and name of the Spokane area rep and requested a meeting with him. I was told I had to do that at local dealer level. June 24, 2025 • I met with salespeople Jon Stone and his manager to discuss options, if any, that I might have. • Told them about my full conversation with Cust. Service Brandy and how upset I was. • She {Brandy) stated that I would need to get the area rep info from them. They said he was due in town the next week and would give me a call so we could have discussions. (NOTE: next week came and went and I did NOT get a call. I was told he had to change his schedule last minute) • Now, I had two trips coming up in Sept. and Oct. that I was driving the truck to. One in Havasau A:Z.. And | Crash: No Fire: No | Unknown |
| Apr 2026 | POWER TRAIN,ENGINE | I have a 2021 GMC Sierra 1500 AT4 3.0L diesel pickup truck with 98,500 miles. The coolant control valve failed on my vehicle and for some reason it is not covered under GM's special bulletin that covers this part 15yr/150,000. Ridiculous. | Crash: No Fire: No | Unknown |
| Apr 2026 | ENGINE | 6.2 lifter failure at 44500 miles | Crash: No Fire: No | Unknown |
| Apr 2026 | ENGINE,FUEL/PROPULSION SYSTEM | Began with a misfire on cylinder 5 code P0305. Replaced spark plugs, wires, and coil pack. Misfire still existed. Fuel injector on cylinder 5 was stuck open and had to be replaced. Misfire still existed. No spark from new coil pack on cylinder 5, replaced coil pack connector. Misfire still existed, but lifter tick became present. Removed cylinder head and found exhaust lifter on cylinder 5 was bad and needed replaced. Currently awaiting parts delivery (only available through GM dealer). Have been without vehicle for 7 weeks now. Was told this was most likely related to Active Fuel Management. | Crash: No Fire: No | Unknown |
| Apr 2026 | ENGINE | -The engine in my 2021 GMC Denali 1500 with the 6.2L engine failed its second engine with ~4,000 miles on the new engine. It is currently at GMC dealer waiting for a 3rd new engine. - Fortunately i was parked when the failure happened and the engine locked up. -Dealer confirmed that a valve dropped and damaged the cylinder wall. - There were no warning lamps or other indication that a failure was about to happen. -Current mileage ~91,000. First motor changed ~85,000 due to recall with previous owner. | Crash: No Fire: No | Unknown |
| Apr 2026 | ENGINE | THE ENGINE COMPLETELY SHUTS OFF WHEN I STOP AT A STOP SIGN OR STOP LIGHT. I HAVE BEEN STUCK IN TRAFFIC INTERSECTIONS ON SEVERAL OCCASIONS UNABLE TO MOVE WHEN THE LIGHT TURNS GREEN. EVENTUALLY THIS WILL LEAD TO ME GETTING REAR ENDED AND PUSHED INTO IN THE MIDDLE OF AN INTERSECTION. MY LIFE IS IN DANGER WHEN I DRIVE THIS VEHICLE. I GOT MY ENGINE REPLACED AND STILL THE SAME ISSUE IS OCCURRING WITH THE AUTO STOP AND START SYSTEM. | Crash: No Fire: No | Unknown |
| Apr 2026 | ENGINE | There is a recall on the 6.2 motor that is in my truck at my last oil change they performed a pico scoop diagnostic on the truck said it passed and gave it the new type of oil and oil cap that was suppose to fix it. Now a couple months later I walk out start my truck to let it warm up and after starting all of a sudden the engine started nocking bad and loss of oil pressure and on dip stick. I looked it up and this is what happens when the engine fails due to the massive recall on the 6.2 engines. I called the dealer and they are having me tow the truck potentially at my expense for them to look at and decide if it falls into the category of the recall after they did the test, and at one point told me that cause they did the test it is no longer recalled. I am being told people who have had the engines replaced because of the recall that the replacement engines have failed as well. I have a 9 month old baby and this left me stranded and unable to pick him up from daycare I had to scramble to find somone able to do so. I'm concerned that this could have happened while driving and having him with me or being left stranded somewhere.I'm glad it didn't happen when I was dropping him off that morning and while I was driving And meanwhile while they look at the issue and decide weather this falls under there recall or not and while it gets repaired I'm left without a vehicle and to be honest I don't feel safe even if they do repair it as there seems to not be an actual fix to the situation. this is unsafe and unacceptable for the price we have to pay for these rigs and the safety regulations and standards we have, how is this even an issue. | Crash: No Fire: No | Unknown |
| Mar 2026 | UNKNOWN OR OTHER | P1098 code coolant control valve fail service bulletin N252508341 my vin not covered but same motor and same part ! | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN | I believe the torque converter is failing. While driving approximately 38 mph and also 48 mph up to 51 mph the vehicle have a vibration feeling like driving on a rumble strip. If you maintain the same speed, the vibration continues if you speed up, slow down, or let off the gas it goes away. There are so many detailed explanations on forums and social media from other customers experiencing the same problem, but not seeing any recall made by GMC. | Crash: No Fire: No | Unknown |
| Mar 2026 | STEERING | Loss of steering, erratic steering control. Steering locks up | Crash: No Fire: No | Unknown |
| Mar 2026 | ELECTRICAL SYSTEM,ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 50-65 MPH on an incline, the contact believed that the transmission was slipping or there was a misfire coming from the engine. The contact stated that the vehicle failed to restart automatically after the engine AUTO Start/Stop system was engaged after a complete stop. Additionally, the contact stated that after driving for a while, the vehicle went into LIMP Mode. The check engine warning light and other warning lights were illuminated. The vehicle was taken to the dealer to be diagnosed. The contact related the failure to GM Campaign Number: N252515590 (Corroded Ground Strap); however, the dealer had informed the contact that the vehicle was not covered because the VIN was not included and there was no warranty coverage on the vehicle. The vehicle was not yet diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 75,000. | Crash: No Fire: No | 75,000 |
| Mar 2026 | TIRES | Tires are LT275/65R20. While driving on interstate at approximately the speed limit and low 80 degree temperatures in South Carolina with proper placard pressure tire inflation checked two days prior, the truck developed a faint vibration which got worse over three or four miles. I slowed my speed and pulled over at next offramp and visually inspected truck for signs of vibration. Including looking over tires. It seemed like a drive line issue, however truck is a 2021 model with only 38,000 miles. After I could not find anything out of place I got back on the interstate to see if problems still existed. I was only traveling at 45 mph and vibration was getting worse, so I tried to slow and make it to next offramp when the driver side tire blew out causing me to have to quickly react to prevent having an accident. The tire tread and multiple parts of the truck inner fender guards and liner were thrown out into traffic and truck bed side is badly damaged. Prior to blow out there were no warnings on the dash board to to indicate any sort of issue and I verified tire pressures when I stopped after the vibration initially set in. The TPMS system was working properly at the time of the blowout. I have the tire if further inspection is warranted. My safety was at risk when tire blew out on the interstate along with vehicles traveling around me to avoid hitting the flying debris and tire tread. Further this was driver side tire and I had to change the tire on the side of the interstate with traffic right beside my vehicle. I called GMC and they said they would do nothing to help because they see tires as a maintenance item and truck is out of warranty period. I am a mechanical engineer having worked many years for major tire company as a tire design engineer. I am very familiar with load ratings, tire wear, life expectancies, and I believe theis tires failed prematurely. I bought this truck new and have always had tires properly inflated a never overloaded. | Crash: No Fire: No | Unknown |
| Mar 2026 | ENGINE | L87 engine failure 4 months after it passed the recall test. Experienced shuddering and rpm fluctuation with the cruise control set. Was thinking torque converter. Got it replaced under warranty and the the issues were still there. A week after new TC the truck was running very rough driving down the road. Check engine light along with a low oil Pressure warning and Lost all engine power going 60mph. Would not re fire. Had to coast to a stop with no headlights on only fog lights. Truck is at dealership now will be needing a new engine. P0016 engine code. The truck was in the shop multiple times for misfire and rpm’s jumping and cruise control turning off on its own. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN | I've been to the dealership a few times due to the truck jerking violently under very light acceleration when its trying to shift gears. also there was a few times that the rear wheels have locked up while driving. | Crash: No Fire: No | Unknown |
| Mar 2026 | ENGINE | I am filing a complaint regarding a catastrophic engine failure in my 2021 GMC Sierra 1500 equipped with the 6.2L V8 engine. While driving under normal conditions, the engine suddenly failed without warning and threw a connecting rod, rendering the vehicle inoperable. There were no prior warning signs such as knocking, overheating, oil pressure issues or even a check engine light. The vehicle has been properly maintained, including regular oil changes using manufacturer-recommended 0W-40 oil. This failure created a serious safety concern due to the sudden loss of power while driving, which could have resulted in a dangerous situation, especially at highway speeds or in traffic. I am aware that General Motors has issued a recall and/or is aware of similar failures involving the 6.2L engine in certain 2021 vehicles. However, my vehicle’s build date falls just outside the currently defined recall range, despite experiencing the exact same type of catastrophic failure described in those cases. My build date is 12/20 and the recall was issued for 3/21. Given the similarity of this failure to known issues, I believe this defect extends beyond the currently identified recall population. This raises concerns that additional vehicles, including mine, are at risk of sudden engine failure without warning. I am requesting that National Highway Traffic Safety Administration investigate this issue further and consider expanding the recall to include additional affected vehicles outside the current build date range. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN,FUEL/PROPULSION SYSTEM | The DEF tank in my truck is defective and its the second time in the last 14 months it has broke. The part is now back ordered and according to the dealership this is a nationwide issue regarding these specific trucks. I have contacted around 10 dealers in my area and all tell me the same thing that they have multiple trucks waiting on the same issue. I have not had my truck for over 2 months and have no idea when i will be getting it back due to dealership having no idea when the part will be released due to the back order. This seems to a huge issue with these trucks and GM is doing nothing to help resolve it. I've reached out to GM directly and get no assistance and now have made 2 payments on my truck and the dealership refuses to give me a loaner vehicle. i am looking for some help or relief on what to do to go about my issue | Crash: No Fire: No | Unknown |
| Mar 2026 | UNKNOWN OR OTHER | When my android auto does not connect, it essentially disables the whole infotainment system which is incredibly distracting and dangerous while driving. I am requesting that this be fixed so that I can still use some of the infotainment system but they are redusing to to do anything to fix the issue. The dealer has advised that they are unable to fix the issue because it is software related but yet the software team is saying it is a dealer issue. Please help me get a resolution to this issue! | Crash: No Fire: No | Unknown |
| Mar 2026 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that on Aug. 14, 2025, the PICO engine test was completed on the vehicle under NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling). The dealer stated that the engine had passed the test, and the engine oil was changed to a higher viscosity oil, and the oil cap, oil filter, and the page in the Owner’s Manual were updated. The contact stated that the vehicle was making abnormal sounds while idling, and the fuel consumption had increased. The dealer was contacted and advised the contact to bring the vehicle back to have the engine test performed again; however, the contact refused. The vehicle was not repaired. The contact stated that the engine test had not been performed on the vehicle and that the vehicle was unsafe. The manufacturer was informed of the failure and informed the contact that the vehicle was repaired. The failure mileage was approximately 44,000. | Crash: No Fire: No | 44,000 |
| Mar 2026 | ENGINE | at roughly 5,000 miles had lifter failure which caused loss of power. That was repaired under warranty. Same issue at 86,000 miles - loss of power. New engine which I had to pay for. Same issue at 126,000 miles. New engine required. Covered under warranty. Side note. New engine will only have balance of warranty from 2nd engine or about 5,000-6,000 miles. first incident Feb 2001, second incident about Nov 2004, third incident Mar 2026. | Crash: No Fire: No | Unknown |
| Mar 2026 | ENGINE | Loss of power, and knocking from the engine while driving. Check brake system, check srs, check parking brake and check engine light flashing came on at the same time. The problem has been reproduced at a mechanics shop and has been determined that cylinder 6 is dead. | Crash: No Fire: No | Unknown |
| Mar 2026 | ELECTRICAL SYSTEM,ENGINE | Following the remedy of the engine recall in 2025, the truck started having intermittent electrical issues (i.e. warning lights on dash turn on/off: service 4WD, Loss traction Control, etc) come one while the truck is being driven. If the truck is turned off while the dash warning lights are on, it will NOT Start for about 24 hours. If the warning lights are ignored, eventually they will go off on their own. Additionally, the truck is having "no-start" problems (randomly the truck does not start, then after a few days it starts). A New development, when backing up there is a scraping/squealing sound (possibly universal joint). Truck has been back to the dealership that replaced the engine block for the recall and they have failed to identify any issues as these problems are intermittent. Engine Recall Replacement Invoice (Attached) | Crash: No Fire: No | Unknown |
| Mar 2026 | ENGINE | Took it to dealer for engine sound said nothing was wrong 4 days later rod bearing went out while driving. Truck no longer able to drive | Crash: No Fire: No | Unknown |
| Mar 2026 | SUSPENSION,POWER TRAIN | Transmission Shuttering which was confirmed from from GMC dealership , but refused to do any repairs after confirmation or diagnostic and test driving. Demanded a 220$ fee be paid before releasing my vehicle back. Also gave GMC Bulliten # 25-NA-148 which states the same issues I'm currently having. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN,ENGINE | Driving down the road and engine shut off and would not start back. Had it towed to dealer and it needed a motor replacement. Waited over a month for the shop to finish it. New motor has 3k miles on it and is making noise, transmission is stuttering hard and the air conditioning quit working all around the same time. Had to take the truck back to the dealer after the replacement motor was installed because of a faulty “new” starter. | Crash: No Fire: No | Unknown |