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 |
|---|---|---|---|---|
| May 2024 | VISIBILITY/WIPER | The wiper blade motor is defective. While driving during a storm the wiper blade motor stopped working on the delayed and low settings. This was a safety issue while driving. I took my vehicle to get looked at a GM Dealer to look at the vehicle. My vehicle is only 3 years old and should not have issues with the wiper blade motor. | Crash: No Fire: No | Unknown |
| May 2024 | SUSPENSION | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 40 MPH, the front driver's side wheel separated and fell underneath the front end of the vehicle, causing the vehicle to veer towards oncoming traffic. The contact was able to pull to the side of the road, where the vehicle was awaiting to be towed. The contact related the failure to NHTSA Campaign Number: 21V718000 (Suspension); however, the VIN was not included. The dealer was notified of the failure. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was 37,470. | Crash: No Fire: No | 37,470 |
| May 2024 | ENGINE | The coolant control valve is faulty and needs to be replaced. GMC and the dealership know about the issue (Bulletin No. PIP5791), but are not fixing it in a timely manner. This is a safety concern as the system will automatically reduce engine power, which is a major concern when towing and/or in mountainous terrain. | Crash: No Fire: No | Unknown |
| May 2024 | ELECTRICAL SYSTEM,ENGINE | The component that has failed is the engine coolant flow control valve AC Delco part number 55516369. Unfortunately the part is still installed on the vehicle. It has been taken to a dealer and this is a known issue but no recall has been issued. The check engine comes on sometimes but not always, sometimes the pickup has plenty of power to drive and sometime it will barely pull itself, all in the same trip without shutting the ignition off. The symptoms first started in December of 2023, but were sporadic, now it is nearly everytime the pickup is started. It is extremely dangerous to drive this vehicle when it has a problem. You cannot tell if it will accelerate normally or is you will push the pedal and it does nothing. The part to repair the problem is on backorder and no release date is yet available. We have been waiting for 3 months and still no word on when this will be repaired. | Crash: No Fire: No | Unknown |
| May 2024 | ELECTRICAL SYSTEM,SERVICE BRAKES | My truck had smoke rolling out at work when I noticed it. Tried to put it out it Burnt my hands ! destroyed the inside I had it towed and insurance investigator said it was do to a brake controller for the trailer. And I took it to get estimate and the service dept said it was do To brake controller my truck was totaled my wallet toast my coat was toast my I phone my deposit my truck i drove daily to work out of and personal. General Motors would not help I called the. First. Then I was frustrated called my insurance they started a claim and low balled me now I lost 2 months of work bills stacked and low ball price on what the offer was) and haven’t gotten one yet. Called gm back they said I had an active claim they woundenr help it’s there defect I lost my job my mind etc on this. Two investigators state the same thing even there service dept. A gm service dept said the same thing. No warning indicators at al I will never buy another truck. The safety issue is people driving around not knowing. The 2500 and 3500 have them. Looked it up the plant that made my truck left the parts for manufacturing outdoors they got wet. It’s on the internet people r gionbg to get hurt. Lucky I was outside when my was on fire. Please help on the matter. Thank u | Crash: No Fire: Yes | Unknown |
| Apr 2024 | ELECTRICAL SYSTEM | Tail gate failing from water intrusion. Wont stay up while driving. Already a recall for it in Canada but nothing in the USA where i see others have the same problem | Crash: No Fire: No | Unknown |
| Apr 2024 | ELECTRICAL SYSTEM,STRUCTURE | Tailgate drops without warning, lower button on tailgate doesn't work. | Crash: No Fire: No | Unknown |
| Apr 2024 | STRUCTURE | The contact owns a 2021 GMC Sierra 1500. The contact stated that there was water leaking through the rear sliding window. The dealer was notified of the failure and advised the contact that a fee would be charged for the repair. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 51,000. | Crash: No Fire: No | 51,000 |
| Mar 2024 | STRUCTURE | I have a 2021 GMC Sierra 1500 with a power 6-point tailgate. The inner tailgate has been spontaneously opening for some reason. It seems the electric lock mechanism trips. This could case the contents of my truck bed to fall out. This issue is a known issue for GMC Sierras and a recall has been issued for the 2500's and 3500's but for some reason not the 1500's even though the tailgate is the exact same. I have an appointment to have the issue serviced at dealership, but since there is no current recall they will not cover the expense. | Crash: No Fire: No | Unknown |
| Mar 2024 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at approximately 75 MPH and depressing the accelerator pedal, the vehicle failed to accelerate as intended. The check engine warning light was illuminated. The contact stated that the vehicle would slow down as if it was losing motive power. The vehicle was driven to a local dealer where it was diagnosed that the coolant control valve needed to be replaced. The vehicle was not repaired due to parts not being available. The manufacturer was notified of the failure. The failure mileage was approximately 32,000. | Crash: No Fire: No | 32,000 |
| Mar 2024 | STRUCTURE | GMC1500 Sierra pick up truck. Rear tailgate dropped today, 3.15.2024. Weather was rainy, tailgate was up at the start of the trip. Contacted GM Corp and was told this model 1500 was not part of the recall?? | Crash: No Fire: No | Unknown |
| Mar 2024 | STEERING | Alignment Cam Guide Pins sheared off while driving on highway. Alignment went all over the place and car was drifting side to side. Also, steering wheel spun a quarter turn while car was not turning but still driving on highway. Almost caused me to crash. GMC does not want to acknowledge the issue or allow me to file a warranty claim. Car could not be driven to GM dealership safely and had to be repaired at closest shop | Crash: No Fire: No | Unknown |
| Mar 2024 | ELECTRICAL SYSTEM | While driving down the road at random times of the day, random days, random drive periods, random locations, the DIC and touch screen along with radio will shutdown and restart, like rebooting the system or just starting the truck. I loose the mph, gauges, navigation, everything on the dash and touch screen the it will come back on like nothing happened. I have contacted 2 dealers and they say I need to download updates but when I go to update it is not required or needed. | Crash: No Fire: No | Unknown |
| Mar 2024 | ELECTRICAL SYSTEM | It started year and a half ago involving my tailgate. The buttons to operate by upper and lower tailgate failed to operate on the rear of the truck, but cab button and remote button would open the full tailgate. Returned truck to dealer and they replaced the rear control. It worked for approximate 4 or 5 months the the total tailgate button failed, half tailgate button worked no problem. About 6 mths ago I went to drive to work and hit a bump felt like something bounced but really didn't think of tailgate being open. Drove on interstate for 7 miles at speed of 70 to 75 mph. I had my structural firefighting equip in the bed. Stopped at a drive thru for coffee then drove 5 miles to other side of town to my workplace put truck in reverse and my camera showed the ground, my tailgate was open. Thank goodness nothing fell out of the bed. 2-3 days later left for work, hit bump and felt the rattle in the rear again, stopped and tailgate down, closed tailgate and it opened again immediate after closing. This has occurred numerous times, now the half gate now unmatched along with entire tailgate and opens hitting hitch, scratched paint off. Thought it was me hitting keys in my pocket but continued to occur with key in cab. My mileage warranty passed so I was waiting to get some extra cash to fix the tailgate latches. Have not seen any recalls for GMC sierra 1500 denali, thought I would file a "complaint". | Crash: No Fire: No | Unknown |
| Feb 2024 | ENGINE | I purchased this vehicle used with approx 16k miles on it. Not long after getting it - as I was driving it started dinging and then would shut off. Sometimes I’m in the fast lane going 75Mph and it’ll just shut off. The dealership can’t get it to repeat itself. They said they’ve heard of it happening before but it throws different codes. There’s no rhyme or reason to causing it to shut off, but here lately I don’t even get the warning bell. It just dies on me. As soon as i shift it to neutral and press start it’ll restart instantly. But it’s scary nonetheless, and causes me to drop speed instantly and poses a safety risk especially when I have semi’s or other vehicles close behind. | Crash: No Fire: No | Unknown |
| Jan 2024 | UNKNOWN OR OTHER | The Flex Tailgate has on multiple occasions has malfunctioned in cold temperatures. I have had instances where I can get it open when I have vital supplies in the bed of my truck because of the Tonneau Cover being on (I have a hard cover made for this truck) and the tailgate malfunctioning. I have also had an instance where my tailgate opened (after clicking shut) while driving without the notification coming up on my dash. I could've been held liable if my equipment fell out and caused an accident. Moral of the story this truck as a lot of issues when temps are below freezing even after being warmed up for 15 minutes or longer. I wouldn't recommend this truck based on the function of the Flex Tailgate. I would prefer a classic a handle and less tech now that I have seen it fail so many times. | Crash: No Fire: No | Unknown |
| Jan 2024 | SERVICE BRAKES | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brakes seized, and the service brakes warning light illuminated. Additionally, the contact stated that the vehicle jerked forward. The vehicle was driven to the residence and parked. The contact stated that the vehicle was turned off; however, the service brakes warning light remained illuminated. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 34,500. | Crash: No Fire: No | 34,500 |
| Dec 2023 | ELECTRICAL SYSTEM | My 2021 GMC 1/2 Serria SLT 4x4 Crew Cab short bed, V-8 Gas engine with Automatic Transmission. I bought this pickup used with apprx. 41k miles on it. I had it about 2 months when I went out to start it and the battery was completely discharged, it would not even click or any lights come on. I hooked it up to a battery charger and got it started, took it to a shop and had the battery and alternator check which both were ok. Drove back home and went out the next morning and the battery was completely drained again, got it started and went an put in a new battery. 16 days later it did the same thing this time it smelled like wires burning when I opened the hood. Called the dealer I bought it from and they put it on a diagnostic machine for over 3 hours could not find anything. Then next morning the battery was again completely drained. Got it started and took it to another shop to get it checked out and after almost 3 hours there they found nothing. Came back home an it sat for just over 40 hours and again the battery was completely drained. I could smell what I think is plastic or rubber when I opened the hood again. My main concern is that this may be a fire hazard and could not only burn up my pick up but my house as well. The check engine light has came on but goes off so I am at a complete loss on this and seems as if GM is not concerned either. I have tried contacting GM but so far nothing other than a note from GM Canada that I need to contact the GM USA, and again that is the only thing I have gotten from anyone. Perhaps this is just a odd thing, I don't know but I do know it is not a safe thing. | Crash: No Fire: No | Unknown |
| Nov 2023 | WHEELS,UNKNOWN OR OTHER | 5 days after purchasing and While driving down the interstate at 80 mph, there was a loud clunk at the same time the back wheels locked up for a split second, long enough to burn the tires and throw everyone in the vehicle forward then the vehicle continued on. It happened three more times, we trailered it and brought it to the dealer. They said nothing is wrong with it. However, I was able to locate the previous owners who stated they'd been bringing it to several dealerships to have it taken care of for the past six months and every dealer said that nothing is wrong with it. But the same thing happened to them for six months. One mechanic in Idaho even replaced the motor trying to fix it and it still continued. The dealer I purchased from never mentioned it having a new motor, and I pulled the Carfax report and it shows several times it was in the shop including the motor replacement, but the shop visits aren't detailed it just says maintenance. Several mechanics we've spoken with say it's in the transmission, drivetrain. But the dealer refuses to do anything unless it'll replicate when they test drive it. But they don't test drive it on the highway or for a long enough time. Multiple owners now in multiple states the same problem and no one will help. This could be a catastrophic incident if the roads had been a little wet or someone was close enough behind us when it happened it would have been a serious car accident, if not worse. I am not sure you can help but Im reaching out to everything that I can find. | Crash: No Fire: No | Unknown |
| Oct 2023 | STEERING,SERVICE BRAKES,ENGINE | "Service parking brake" "steering assist is reduced drive with care" comments showed up on screen…check engine light on, truck shaking/ vibrating completely as if wanting to turn off this all happened while driving on the road and randomly happened…please help..very Concerned | Crash: No Fire: No | Unknown |
| Sep 2023 | ENGINE | Lifters camshaft malfunction. Known issue with 2021 GMC Sierra 20,000 miles | Crash: No Fire: No | Unknown |
| Sep 2023 | ELECTRICAL SYSTEM | Tailgate opens when driving and when parked. I thought something must of hit the button on the dash the first time it happened but now it is constantly doing it on its own. It has damaged the hitch. | Crash: No Fire: No | Unknown |
| Aug 2023 | SERVICE BRAKES | WHEN DRIVING HOME AFTER PICKING UP MY 2.5-YEAR-OLD AND 6-MONTH-OLD THE BREAKS FELT VERY ODD AND NOT RIGHT. WHEN I APPLIED THEM, IT FELT ROUGH TO APPLY AND THEN HEARD A NASTY SOUND COMING FROM THE REAR OFF TRUCK. I TOOK MY TRUCK IMMEDIATELY TOO THE DEALER AND JUST GOT THE PHONE CALL BACK THAT THE MASTER CYCLINDER FOR MY BRAKE SYSTEM NEEDS TO BE REPLACED. THIS VEHICLE HAS 22,500 MILES ON IT AND IT ALREADY NEEDS SOMETHING FIXED LIKE THIS IS PRETTY SCARY SINCE MY FRIEND JUST HAD IT HAPPEN TO THEM AND THEY GOT IN A MAJOR CAR ACCIDENT. THANK GOD I DIDNT HAVE TO PUT MY FAMILY THROUGH THAT. HAVING A BREAK FAILURE IS SOMETHING NOONE WANTS AND NOT WHEN THE VEHICLE IS PRETTY MUCH BRAND NEW STILL. THE DEALER HAS CONFIRMED THAT THIS IS A VERY RARE CODE IN TERMS THEY USED TO BE HAPPENING. THERE WAS NO WARNING LIGHT OR ANYTHING IT JUST HAPPENED THEN AS I WAS TAKING IT UP TO THE DEALER, I GOT THE SERVICE BRAKE SYSTEM ALERT ON MY DASH. | Crash: No Fire: No | Unknown |
| Aug 2023 | POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM | After having simple oil and filter, and engine and cabin filter replaced at Alpine Buick GMC in Colorado Springs, CO, I received my vehicle back and noticed a complete difference in performance. It hesitates when accelerating, stays low in every gear, and bounces, and I mean bounces hard, when shifting gears, especially slowing down. When slowing down, as it shifts to the next lower gear, it almost pushes the truck forward against me pushing the breaks. Then, when feathering to accelerate slowly, it almost bounces back up to speed, hesitating until I let off the accelerator pedal a little, and it immediately shifts to about 1000 rpm in gear. I have to push really hard for it to go up a gear, and when it does, it has lost all power. My vehicle doesn’t run right anymore after my service appt. I have brought it to my hometown dealership and they say it runs fine and nothings wrong. But there is something wrong with it. | Crash: No Fire: No | Unknown |
| Aug 2023 | POWER TRAIN | Transmission shifting is at times confused causing the vehicle to jump forward shifting to first gear. It pushes your vehicle 2-5 miles an hr faster when slowing down. The transmission also does the opposite when letting off the accelerator, shifting fast to a lower gear slowing the vehicle down quickly in a jerking motion at times. I have an 8 speed transmission. GMC dealer is replacing my torque converter, stating this may fix the issue, but it is a safety concern. | Crash: No Fire: No | Unknown |