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 |
|---|---|---|---|---|
| Jun 2025 | POWER TRAIN | coolant control valve failure activating check engine light, reduced power mode and fan running continuously. Truck has been in the shop for 3 weeks already with no part available. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | I heard a ticking in the engine and noticed multiple warning lights in the dashboard. I called the GMC dealer and was told the next opening was several weeks away. I was also told that it would be OK to drive the vehicle which I did (~10 miles) and parked the truck in my driveway until I could get the truck in for a diagnostic evaluation. The service department at the GMC dealer where the vehicle was purchased identified a defective camshaft/lifter as the source of the noise and lights. The service manager recommended either an engine rebuild at their shop or purchase a replacement motor from the GMC inventory network. The serial # of the old motor is: 126852545. The serial # of the new motor is: 40208378. The cost of the new motor, replacement of required fluids and parts and labor was $12,360. 100% of the repair was paid by myself. The .pdf of the service record (RO #: 9189240) exceeds the 10 MB limit and cannot be uploaded. I have a hard copy if needed. The dealership where the vehicle was purchased and serviced is: TULLEY Buick - GMC - BMW - Mazda P.O. Box T 147 Daniel Webster Highway South Nashua, New Hampshire 03060 (603) 888-0550 www.tulley.com | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds, the check engine warning light illuminated, and the engine fan activated and operated at a very high velocity. Additionally, the message "Engine Power Failure" message was displayed, and the vehicle stalled. The vehicle was taken to the local dealer who diagnosed that the engine coolant control valve was faulty and needed to be replaced. The contact was informed that the parts were on backorder and no repairs were performed. The manufacturer was not yet contacted. The failure mileage was 45,000. | Crash: No Fire: No | 45,000 |
| Jun 2025 | ENGINE | I had an engine warning warning light on my dash around May 5th. A notice of reduced speed also lit up my dash while I was on the freeway. I scheduled a service for May 15th and was told the engine coolant flow control valve needed to be replaced. I was also told there was a backlog of other vehicles waiting for the same part. It has been over a month and I am still unable to drive my truck which I use for work. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact stated upon starting the vehicle and shifting to drive(D) in the morning, the transmission hesitated to shift to second gear and then shifted harshly. There was no warning light illuminated. The vehicle was taken to the dealer, where it was test-driven, but the failure could not be duplicated. The contact stated that the failure occurred once a day on first start-up of the vehicle and upon shifting to drive(D). The vehicle was taken back to the dealer over the weekend, and the dealer was able to duplicate the failure on first start-up of the vehicle and upon shift to drive(D). The dealer related the failure to TSB Number: 16-NA-361; and informed the contact the manufacturer had not made a repair available. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to file a complaint. The failure mileage was unknown. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at various speeds, the check engine warning light illuminated, and the engine fan activated and operated at a very high velocity. Additionally, the message "Engine Power Failure" message was displayed, and the vehicle stalled. The vehicle was taken to the local dealer who diagnosed that the engine coolant control valve was faulty and needed to be replaced. The contact was informed that the parts were on backorder and no repairs were performed. The manufacturer was not yet contacted. The failure mileage was 48,000. | Crash: No Fire: No | 48,000 |
| Jun 2025 | ENGINE | My Truck has been consuming oil since new, latest documented consumption test was 1.25 quarts in 1967 miles. GM dealership said that is normal and no further diagnosis is required. GM says acceptable consumption is 1 quart per 2,000 miles. This truck has a 6.2L engine that is not under the current recall ( N252494000 ). The engine problems affect more vehicles that the current recall and should be investigated. | Crash: No Fire: No | Unknown |
| Jun 2025 | UNKNOWN OR OTHER,ENGINE | Dealer keeps ignoring engine knock noise states its normal , mpg is down dramatically . Shift to park , vehicle only has 34k miles and dealer does not want to repair under warranty due to vehicle being a 2021 Battery keeps draining for no reason , new battery added still does the same thing | Crash: No Fire: No | Unknown |
| Jun 2025 | FUEL/PROPULSION SYSTEM | - #5 injector failure, no. - Once the injector failed, the vehicle would violently shake when trying to accelerate. - Yes, was not covered under factory warranty but replaced by third-party extended warranty. -Yes, replaced by the dealership. -No warnings prior, once the injector failed warning for brake system check and vehicle mileage limits set in warning. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was unavailable. The dealer was not contacted and confirmed that parts were not yet available. The manufacturer was not made aware of the failure. The contact had not experienced a failure. VIN tool confirms parts not available. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN | received my truck back after replacement of the front transmission pump and idle gear, the same day the transmission had horrible down shifts, sometimes it would just downshift into neutral and bounce off the rev limiter. the service advisor told me that my transmission had to "relearn" my driving habits when I called him and would take 200-400 miles.. i drove it one more day and drove it back to the dealer to have them drive it. the agreed that something was wrong, but didn't know what and had to contact gm engineers. 2 days later they told me that the valve body needs to be replaced. I dropped it off to find out that it had been ordered with zero ETA of when they will receive it.. so now im stuck with a loaner and no ETA on when parts will be available. | Crash: No Fire: No | Unknown |
| Jun 2025 | AIR BAGS,WHEELS | • The airbag system failed to deploy during a collision that resulted in the total loss of the vehicle. Additionally, the vehicle was operating with a 17” spare tire (undersized compared to the standard 20” wheels), which may have contributed to the accident. The vehicle has been totaled and is currently in the possession of the insurance company, but may be available for inspection upon request. • Despite the severity of the collision, none of the airbags deployed, which could have resulted in serious injury if the circumstances were different. The use of an undersized 17” spare tire may have affected the vehicle’s stability, braking, or performance, contributing to the crash. • No. The vehicle was declared a total loss and has not been evaluated for defect reproduction by a dealer or service center. However, I am aware of related recalls and lawsuits regarding both improper spare tire sizing and airbag non-deployment in 2020–2021 GMC Sierra models. • The vehicle has been inspected by the insurance company during the total loss evaluation. A police report was also completed at the scene of the accident. To my knowledge, the manufacturer (GM) has not inspected the vehicle at this time. • No. There were no warning lights, messages, or symptoms prior to the crash. The vehicle gave no indication of any issue with the airbags or tire compatibility leading up to the accident. I was involved in an accident in my 2021 GMC Sierra. At the time, the vehicle was operating with a 17” spare tire installed, which I later discovered may be significantly undersized compared to the standard 20” wheels. During the crash, the impact was severe enough to total the vehicle, but none of the airbags deployed. Fortunately, there were no injuries, but I believe the non-deployment of the airbags represents a critical product safety defect. I’ve since learned that GM has recalled similar vehicles for incorrect spare tires, and that lawsuits have been filed regarding calibration issues. | Crash: Yes Fire: No Towed | Unknown |
| Jun 2025 | ENGINE | Engine seized while at idle speed and has to be replaced. It was a catastrophic event, but not covered under the current recall for 6.2L L87 engines. | Crash: No Fire: No | Unknown |
| Jun 2025 | STEERING,SERVICE BRAKES,ENGINE | While traveling on the interstate the vehicle lost all propulsion and started to rapidly decelerate. Shortly after propulsion was lost the engine turned off completely affecting the steering and braking of the vehicle. The vehicle was towed to the GMC dealership that we purchased it from. repairs have not begun so I assume it would be available for inspection. We were traveling on a three lane interstate up a grade at 80 MPH. Had I not been able to safely get the vehicle stopped and out of traffic or had we lost control going down a grade we would not have been able to stop the vehicle and there would've potentially been a catastrophic accident most likely resulting in injury or death. No the dealership has not diagnosed the failure physically. The service writer did suggest that it sounds like the failure reported from the recall not being addressed. I did contact the dealer about the recall on Saturday May6th. At which time I was informed there was not a solution for the vehicle for my vehicle at that time. There were no warning prior to the incident. After the engine stopped operating there was a warning produced on the instrument panel that read "Engine Oil Hot" and the instrument panel no longer registered any oil pressure. | Crash: No Fire: No | Unknown |
| Jun 2025 | VISIBILITY/WIPER | I don't believe this needs to have an investigation, but i would like it documented and brought to GM's attention for future body designs. I have never had as many rocks/debris hit my windshield as I have with this truck. I have had one chip in a windshield in 30+ years of driving, until this truck where I have had several that needed repairs, and this last one has created a Crack large enough where my windshield needs replaced. It may be bad luck, but I've talked to multiple other Sierra owners and most of them have had the same issue. A couple have had the windshield replaced almost yearly. Please at minimum inform GM engineers to possibly determine the cause (I assume aerodynamics) so they can incorporate the flaw (if there really is one) into future designs. The photo I included happened almost immediately after the impact. The crack has grown several inches since as expected. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | Reached the 100,000 mile mark and the truck started shuddering. Took it to the dealership and they tell me the torque converter is coming apart and I need a new transmission. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ENGINE | My truck has a known recall from GMC which results in total loss of propulsion. It has not failed yet, but this is dangerous to me, my family/kids, and potentially others on the road. I have made multiple attempts to speak with GMC about the issue and also my local dealer. Neither group will provide concrete information as to when they can look at/service my truck even though there is a known remedy - [XXX] I brought my car into the dealer December of 2024 for brakes and also a rattling noise since it was uncharacteristic. Noises can be indicative of this larger problem (which I know now and didn't then) but they "didn't hear a rattle" and the "condition could not be duplicated" which is patently false since it still makes the noise/has gotten worse. Since then, I have taken the following actions: - I called and spoke with the local dealer service team on 5/5 - was told since it's showing incomplete, no remedy available there was nothing they could do - Spoke with GMC on 5/5 - they directed me to the local dealership - Made an appointment online on 5/10 to get my truck serviced and to check for this problem - They immediately called me first thing on Monday 5/12 to cancel my appointment and again tell me there is nothing they can do about this issue - I have continued to express my safety concerns to both parties - I spoke to GMC today, 5/30 and was told that there is no timeline for the issue (with my VIN) even though the remedy is known - An appointment is scheduled on 6/12 with my local dealership, but if I recall status hasn't changed, they will not check for this problem INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | front idler gear for the transmission pump failed at 39500 miles. was fixed under GMC warranty. but now after getting the truck back the transmission has extremely harsh down shifts. still waiting for GM to figure out what to do next.. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ENGINE | The truck ever since of bought it has been nothing but issues. Starting with the fuel pump issues then electrical issues and most recently the coolant flow control valve. This is my work truck and now I’m out of a truck with no loaner and the dealership has no eta. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | I’m filing a complaint regarding GM Recall N232404000/N232404002, which affects the L87 6.2L V8 engine in my 2021 GMC Sierra 1500 AT4. This recall is tied to a serious defect that can cause sudden loss of propulsion due to internal engine failure. My vehicle has shown symptoms since purchase — including engine ticking, unusual noises, and low oil levels — all documented by dealership service records. GM originally instructed dealers to replace engines based on build date, which made sense given the nature of the defect. But now they’ve changed the remedy midstream. Instead of replacing potentially defective engines, they perform a PicoScope test, and if it “passes,” the only action taken is replacing the oil with a different grade. This does nothing to resolve the underlying issue. How does a manufacturer go from replacing engines due to internal failure risks to simply changing the oil and calling the problem solved? This undermines the purpose of a safety recall and places future liability on the consumer. A known internal mechanical defect cannot be fixed with an oil change, yet GM is closing out cases this way. Now I’m stuck with a vehicle I can’t fully trust — one that may still fail unexpectedly — and possibly face diminished resale or trade-in value due to an engine that other buyers will view as unreliable or patched over. GM is leaving owners with the long-term risk while clearing their books of liability. I urge the NHTSA to investigate whether this revised approach truly meets federal recall standards. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was unavailable. The dealer was contacted; however, the contact was informed that parts were not yet available for the recall repair. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | Unknown There is a recall on the this model but with different motor but when I took mine in they said it was a.manufactured defect but I was out of warranty because I purchased it cash and didn't get extended warranty now im having to replace and pay for a head and new engine over 10,000 when vehicle doesn't even have 70,000 miles it started with a engine light going on amd off for 2 weeks then it just stopped working It's too coincidental that the sister truck make n model to this had a recall for exactly what is wrong with mine | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | We have the 6.2 liter GM engine that has lost propultion. We are not covered in the recall and are 30,000 miles above the milage warranty, but still within the time portion of the warranty. GM payment assisitance has only offered us $1600 to help with replacing our engine. The dealership told me their warranty parts price was higher, so it really didn't offset any cost. This is our ONLY vehicle for our small appliance repair business. Our vehicle was manufactured at the plant in Canada where all the other faulty engines were manufactured. Please consider widening the recall to include our vehicle. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the low oil warning light illuminated. The vehicle was taken to the dealer but was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 67,600. | Crash: No Fire: No | 67,600 |
| May 2025 | ENGINE | My GM 6.2L V8 engine has seized in less than 100K Miles. Thankfully not whilst driving and being potentially harmful to myself or others with the catastrophic failure. This problem is being widely report and continually occurring. GM is saying that I am not included in the massive recall for this, However NHTSA notes the vin range as NR and indicates incidents are still occurring. Seems to be a real lemon situation here and even bigger a letdown to uphold consumer safety. | Crash: No Fire: No | Unknown |