Complaint volume
519 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
519 consumer-submitted complaints on record for the 2021 GMC Sierra, grouped by component category.
519 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 109 complaints, with an average reported failure mileage of 51,910 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 169
POWER TRAIN 64
ENGINE AND ENGINE COOLING 40
POWER TRAIN,ENGINE 29
ELECTRICAL SYSTEM 26
UNKNOWN OR OTHER 16
STEERING 13
UNKNOWN OR OTHER,ENGINE 12
ELECTRICAL SYSTEM,ENGINE 10
SERVICE BRAKES 9
519 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Apr 2025 | POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM | Engine power reduced, could not accelerate, fuel pump issue and was bucking the engine Went to dealer and complained as gmc not working to help me, dealer fixed issue but said no other complaints out there and car was fixed, gmc called me several times and keeps saying no issues with the vin associated. The car was fixed but I am stuck with a truck that is probably not saleable once these issues continue. This issue happened initially with 30 k on it and dealer could not find the issue and this times at 61500 happened again | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN,ENGINE | was getting on the interstate whenever i hit 70 mph just heard a hard knock in the engine and truck was driving rough. the truck it self dropped to 60mph. before it occurred there was no check engine light on or anything. after i had the dash light up with engine light, brake light, stability light. about a week later took it to the dealer they said it was fuel injectors they replaced it took them about 2weeks but the problem wasn’t resolved but then stated it was the lifters which they said it almost common for this to happened. so i took it somewhere else to get replaced and they said yes it was the lifters and i needed to replace the camshaft because when the lifters go out it will damage the camshaft. all they did to diagnose my problem was hear it was ticking and the knocks also with the codes from the dealer diagnosis. after my repairs it was expensive least to say | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Engine light came on, went to the dealership where I bought the truck less then two weeks prior. The Chevy dealership ran diagnostic test on it. They said it was the Engine Coolant Control Valve. This is a common problem with the 3.0 Duramax diesel engine. I belong to a group on Facebook with the same truck as mine. they are all having the same issue. We are waiting for a recall. the part is on back order and cost $300 just for the part plus labor. I bought the extended warranty and they said it did not cover this part. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Had the car since 2021. Recently started shaking while driving over 45 mph. Took the car in gmc dealership where they told me it’s an engine issue and need a brand new engine. How would I need an engine having the car for 4 years? And there is no recall? | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN,ENGINE | July of 2023, lifters failed on left side of engine. Lifters replaced and cam shaft replaced. January 2025, lifters failed on right side of engine. Replaced. March 2025. Engine seized on interstate. Truck lost all power while driving, no warning signs prior. Dealership has no rental vehicles and we are not old enough to rent from a third party company so family had to drive 9 hours to our location so we wouldn’t be stranded. Three times this truck has failed us. GM is putting in a new motor as it’s still under warranty, but the new motor has no additional warranty. So basically this new motor will be warrantied for less than 7k miles. They cannot say if the new motor has the remanufactured lifters or not. So we could be facing the same exact issues. Can’t ever get ahold of anyone directly though GM. | Crash: No Fire: No | Unknown |
| Apr 2025 | ELECTRICAL SYSTEM,ENGINE | Transmission recall was performed at a gmc dealership. Vehicle has been the the shop repeatedly since. Coolant control valve crank case position sensor new catalytic converter and dpf system. New low temp coolant loop pump. In the shop now for another low temp coolant pump that’s been shorted out. Seems to have on going electrical issues since recall was performed | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 70 MPH, several unknown warning lights illuminated, with the message to shift to neutral displayed. The contact pulled over to the right side of the road and attempted to restart the vehicle; however, the vehicle failed to respond as needed. An unknown dealer was contacted. The contact stated that the failure had occurred on several occasions. The vehicle was towed to the dealer, where it was diagnosed that the engine was damaged and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and offered a monetary payment. The approximate failure mileage was 80,000. | Crash: No Fire: No Towed | 80,000 |
| Apr 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal sound coming from the engine compartment. The contact pulled over to the side of the road and discovered that the engine oil level was low. The check engine warning light was illuminated. The failure occurred on several different occasions. The vehicle was taken to a dealer, where it was diagnosed that the lifters needed to be replaced. The vehicle was repaired; however, the failure persisted. The vehicle was taken to a different dealer (Legacy Westbank Buick GMC; 3611 Lapalco Blvd, Harvey, LA 70058) to be diagnosed. The vehicle was not diagnosed or repaired. The contact was taken to a different dealer (Mossy of Picayune; 241 Frontage Rd, Picayune, MS 39466) where it was diagnosed that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 27,000. | Crash: No Fire: No Medical attention | 27,000 |
| Apr 2025 | ELECTRICAL SYSTEM,SERVICE BRAKES | ESC ERROR PARKING BREAK NOT RELEASING Dashboard lights started flashing Check engine light came on | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | at 16,000 miles Bank 1 lifters fail and replaced under warranty. now at 90190 miles Bank 1 lifters have failed again this time damaging the camshaft. I have all the service records for this engine and I was verbally assured by GM in 2021 that they would cover this repair until 100,000 miles. I know from looking on Google and talking with service advisors at GM that the 6.2L ecoTec3 V8 engines are having multiple problems related to my issue. GM should be able to warranty this engine to 100,000 miles and from past experience this engine should last 200,000 with good service. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Driving 75mph towing a 24' trailer and the motor just shut down and almost caused a massive pile up on [XXX] . INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Apr 2025 | ELECTRICAL SYSTEM | This truck, along with many others, has had wiring harness issues. My truck has fought this issue within the first six months of owning the truck. Since Jan 2025 it has left me stranded 3 times to be towed, and in the shop a total of 6 times for wiring harness issues. Rubbing that GM is 100% aware of how its designed. This has caused the truck to hesitate, shake, lunge, go in and out of gear severely hard then shut off while driving. All three time this happened to me recently i was on the interstate. GM has work orders out with all the codes and symptoms but wont do anything about it. Yes, i am out of warranty, but i am now paying over $5,000 for a new harness to be installed by a different dealer. The dealer that had always worked on this truck requested $8,100 so i called a new GM shop. This is a large issue and they keep turning their back and not addressing the issue and putting drivers at risk! Can provide last diagnostics and can request all notes from Stoops Buick GMC in Muncie Indiana, i have a rather large file there on this truck. | Crash: No Fire: No | Unknown |
| Apr 2025 | UNKNOWN OR OTHER | My tailgate will randomly open on its own. I’ve had several instances( 5 or 6 times so far) when I’ve had open on its own. Only once so far when i was driving. Luckily, i was on my private road without anything in my bed that could fall out. I often carry mountain bikes over the tailgate which could pose a serious danger if the tailgate were to open when driving. Also earlier this evening when the tailgate came down on its own while driving, when I got to my destination, I was unable to open the tailgate at all from outside the vehicle. It is apparent the button to release the switch is malfunctioning. I was able to get it to open by using release button inside the vehicle. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Driving on highway at approximately 70 mph and the engine completely cut off without warning. Error message on dash said put car in neutral and press the start button. After safely pulling over, the vehicle was never able to start or even crank. Towed back to the dealership. Catastrophic engine failure according to the dealership. Vehicle has the 6.2 V8 engine with known issues by GMC apparently. Only 32k miles and under warranty but dealership reports that replacement engines are on back order and they have not been able to source one. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Engine failure. Engine Locked up and truck shut down in the middle of the Freeway. Barely made it to the side of the road. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Lifter failure resulting in damage cam shafts | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN,ELECTRICAL SYSTEM,LATCHES/LOCKS/LINKAGES | The contact owns a 2021 GMC Sierra 1500. The contact stated while the vehicle was parked, the contact attempted to turn off the vehicle; however, the vehicle remained running. A message was displayed to shift to park(P). The contact stated that the lights, radio, and other functions remained operational. On another occasion, the vehicle jerked, and the steering was difficult to turn. The dealer was contacted; however, the vehicle had not been taken to be diagnosed or repaired. The contact also stated that the trunk failed to fully close. The message that the trunk was open was displayed. The contact attempted to close the trunk and message on the displayed was turned off; however, the trunk remained slightly open. The vehicle was not taken to be diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 63,315. | Crash: No Fire: No | 63,315 |
| Apr 2025 | POWER TRAIN | Transmission will slam hard then truck goes into low power mode and doesn’t shift. | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at 50 MPH, the transmission independently downshifted and the rear wheels seized. The contact stated that the rear wheels skidded. In addition, the contact noticed an abnormal clunking sound. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The dealer was made aware of the failure. The contact stated that the failure occurred immediately after the recall repair under NHTSA Campaign Number: 24V797000 (Power Train) was performed by the dealer. The manufacturer was not made aware of the failure. The failure mileage was unknown. | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN | P1098 coolant Control Valve malfunction and out of stock | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | At cold start-up, engine (6.2) makes a metal-to-metal grinding sound for 60-90 seconds. After warm-up, a steady tick on the right side of the engine while running. I contacted GM and they said, " this was normal at start up". however, with me being a mechanical engineer, all of my school and working experience tells me anything grinding metal to metal is not good. | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE | Engine seized and now we need a new motor | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN | I own a 2021 GMC Sierra 1500 Duramax diesel. At around 60,000 miles, I received an engine coolant system alert through OnStar and retrieved a P1098 trouble code, which indicates a failure in the coolant control valve. This issue causes the engine fan to run excessively, creating loud noise, reduced fuel economy, and possible drivability concerns. After researching owner forums and talking to multiple service departments, I discovered this is a widespread problem among 2020–2022 GMC/Chevrolet Duramax 3.0L diesel owners. In many cases, the coolant control valve is failing prematurely, and the replacement part is on national backorder, suggesting a high failure rate. GM has not issued a recall or service bulletin to address the issue, and many customers are being told to pay out of pocket despite the systemic nature of the failure. This component is tied to engine temperature control, and failure could pose a safety risk if the engine overheats or derates unexpectedly. I am filing this complaint to document the issue and request NHTSA investigate this as a potential defect. | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN,ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 30 MPH, there was an abnormal knocking sound coming from the engine compartment, after which the vehicle lost motive power. The contact was able to pull over to the side of the road. No warning lights were illuminated. The vehicle was taken to a dealer, who determined that the engine needed to be replaced. The vehicle was repaired. The contact stated that prior to the engine failure, the transmission was replaced. The manufacturer was not notified of the failure. The failure mileage was approximately 20,000. | Crash: No Fire: No Towed | 20,000 |
| Mar 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train); however, the dealer was unable to complete the recall and returned the vehicle to the contact in a worse condition than when the contact had dropped the vehicle off at the dealer. The contact stated that while attempting to drive the vehicle off the dealer parking lot, the check engine and reduced power warning lights flashed on the instrument cluster. The contact stated that he returned the vehicle to the dealer and was informed that the vehicle could not be repaired. The manufacturer was not made aware of the issue. The failure mileage was approximately 114,000. | Crash: No Fire: No | 114,000 |