Complaint volume
489 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
489 consumer-submitted complaints on record for the 2021 GMC Sierra, grouped by component category.
489 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 38
POWER TRAIN,ENGINE 29
ELECTRICAL SYSTEM 26
UNKNOWN OR OTHER 15
STEERING 13
UNKNOWN OR OTHER,ENGINE 12
ELECTRICAL SYSTEM,ENGINE 9
SERVICE BRAKES 9
489 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Oct 2025 | POWER TRAIN,VEHICLE SPEED CONTROL,ENGINE | DTC CODE P1098 PRESENT RELATED TO FAULTY COOLANT CONTROL VALVE ON 3.0 DURAMAX DIESEL ENGIINE. THIS IS A KNOWN ISSUE WITH THIS ENGINE AND IS SUPPOSED TO BE COVERED UNDER THE 100K MILE POWERTRAIN WARRANTY. PREVIOUSLY TOOK VEHICLE INTO DEALERSHIP FOR REPAIR INVOLVING REPLACEMENT OF THE COOLANT CONTROL VALVE BUT WAS TOLD REPROGRAMMING OF THE ECM WAS REQUIRED FIRST STEP PER GM REPAIR BULLETIN. REPROGRAMMING COST ME $195 AND WAS TOLD THIS WAS NOT COVERED UNDER THE 100K POWERTRAIN WARRANTY. NOW, A FEW MONTHS LATER, THE SAME ISSUE AND DTC CODE P1098 HAPPENED AGAIN WHILE DRIVING ON FREEWAY AT FREEWAY SPEEDS AND CAUSED VEHICLE COMPUTER TO LIMIT SPEED OF THE VEHICLE WHICH CAUSED HAZARDOUS SITUATION IN CONSTRUCTION ZONE AS WAS NOT ABLE TO MAINTAIN SPEED OF TRAFFIC WHILE TOWING TRAILER WITH BOAT. I ALSO UNDERSTAND THAT GM HAS ISSUED SPECIAL EXTENDED WARRANTY RELATED TO THIS COOLANT CONTROL VALVE IN SEPTEMBER 2025 WHICH EXTENDS THE WARRANTY COVERAGE UP TO 15 YEARS AND/OR UP TO 150K MILES BUT I WAS TOLD AT THE DEALERSHIP THAT MY VIN# DOES NOT QUALIFY FOR THIS EXTENDED COVERAGE FOR SOME UNKNOWN REASON? | Crash: No Fire: No | Unknown |
| Oct 2025 | UNKNOWN OR OTHER | The retractable running board on the driver side retracted well my 3-year-old daughter was climbing into the back of the truck. She then fell off and to the ground. On more than one occasion, I was standing on the retractable running board on the driver side. I was buckling my daughter up in her car seat. The running board retracted in without me doing anything. I did not touch the door and had the driver's side driver door and passenger door open at the same time. This has also happened when just the passenger door was open. The running board retracts and knocks my shins into the truck body. This is quite dangerous and could easily cause great harm. I am not the only one with this issue and have read numerous complaints in online forums. I came across a potential remediation of the problem in an online forum. That remediation included disconnecting the rear toes switch that moves the running board towards the back of the truck, allowing a person to easily reach items that have slid all the way to the front of the bed. Since I disconnected that I have not had a problem with the driver side running board. The passenger side running board is not exhibiting this behavior. For clarity, the running boards are the factory installed running boards, not an aftermarket running board. Please get GM to fix this blatantly obvious safety concern. Thank you very much. | Crash: No Fire: No | Unknown |
| Oct 2025 | ENGINE | Vehicle showing signs of a failing coolant flow control valve and/orcoolant temperature sensor. - AC takes a long time to cool down - Engine fan will stay on after the vehicle is shut off - I often see the notice of “A/C Off Due To High Engine Temp” From what I can find, this issue I’m experiencing is a known point of failure in this vehicle make/model/year. On 10/10/2025, I took the vehicle to Fountain Buick GMC Service in Orlando, FL. The service manager recognized the symptoms immediately, and even knew right away that the part to fix it was on back order - further bolstering that it is an issue that GM is aware of and deals with regularly. Per the service manager, GM’s initial response was to issue a “pay to play” software update that is covered under the 3yr/36,000 warranty, but not the 5yr/100K. Out of warranty, this “solution” costs $499.99, and has a < 10% degree of success. If the update doesn’t fix the issue, then it would be covered. However, the need for the software update was not communicated to consumers. Regardless, since the issue is not yet severe enough to be recognized via code (despite symptoms, pictures, and video), GM will not take any action under warranty towards fixing it at this time. The vehicle’s 5yr/100K warranty expires on 10/15/2025. If the code throws on 10/16/2025, it will not be covered under warranty, but *may* be covered under dealer assistance. And regardless, the $499.99 charge will apply, independent of warranty coverage. More important than the money is the safety. The engine’s temperature is not being regulated, the symptoms I’m experiencing are terminal, and this issue will not be fixed on its own. | Crash: No Fire: No | Unknown |
| Oct 2025 | POWER TRAIN | Transmission on my vehicle has failed three times since I bought the vehicle in October of 2021. Vehicle currently has 39,000 miles. First transmission issue was resolved by the dealership by replacing the transmission valve body. This solved the problem for approximately 12,000 miles. In September of 2025 with 39,000 miles the transmission suffered a catastrophic breakdown which lead to complete transmission replacement. After being “fix” the vehicle suffered another catastrophic transmission failure within 400 miles of the complete transmission replacement. This incident caused the vehicle to shut completely down and I was stuck in the traffic lane of the US Highway. Fortunately my vehicle and I were not struck while waiting 30 minutes for a tow truck. Presently the vehicle is back at the dealership awaiting repair. From my review of available on-line information it appears there are 10’’s of thousands of GMC Sierra pickups with major transmission issues. This needed to be addressed before someone is killed due to the poor quality of these GMC trucks. | Crash: No Fire: No | Unknown |
| Oct 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. While the contact's husband was driving at an undisclosed speed, the contact noticed an abnormally bumpy ride. The contact felt as if the vehicle was driving over rocks. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, parts were not yet available for the recall repair. In addition, the contact stated that the vehicle had been at the dealer for more than two months awaiting parts. The manufacturer was made aware of the failure and a case was filed. The failure mileage was approximately 80,000. | Crash: No Fire: No | 80,000 |
| Oct 2025 | ELECTRICAL SYSTEM,UNKNOWN OR OTHER | I took my truck through a car wash and then parked at my parents house. While the vehicle was parked, the trunk latch kept releasing. The trunk popped open. I left it open but you could hear the latch continually releasing and the lights blinking. This went on for an hour and I was unable to drive home because my trunk kept unlatching! A recall was released for other Sierras but not mine. Please investigate my vin and others that may be affected. | Crash: No Fire: No | Unknown |
| Oct 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 45-50 MPH, the engine revved and the transmission unintendedly downshifted, causing the vehicle to decelerate unexpectedly. The transmission then seized, and the vehicle skidded. No warning light was illuminated. The vehicle was towed to the dealer, who determined that the transmission had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 127,000. | Crash: No Fire: No Towed | 127,000 |
| Oct 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign number: 24V797000 (POWER TRAIN), and the dealer performed an interim repair on the vehicle. In March 2025 the part was available, and the recall repair was completed. The contact stated that on one occasion, while driving at an undisclosed speed and then coming to a complete stop, the vehicle jerked and the transmission unexpectedly downshifted. The message “Low Power Mode” was displayed on the instrument panel. The vehicle then failed to accelerate as intended while depressing the accelerator pedal. The contact drove to a parking lot and turned off the vehicle. The vehicle was towed to Don Moore Chevrolet GMC, where it was diagnosed with transmission control valve failure. The contact was informed it would be months before the repair could be performed. The vehicle was towed to another dealer, where the transmission control valve failure was confirmed, and the contact was informed there were metal shavings found inside the transmission. The vehicle remained at the dealer unrepaired. The manufacturer was made aware of the failure. The failure mileage was approximately 115,000. | Crash: No Fire: No Towed | 115,000 |
| Sep 2025 | POWER TRAIN,ENGINE | Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working” | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN | Transmission failure at a little over 120,000 miles while towing a side by side on the highway. This highway has a speed limit of 80 which is dangerous when the vehicle stops working properly for myself and any other drivers in itself. Earlier this year the transmission had been updated due to a recall and was deemed to work good by the dealership but didn’t notice any difference. Had an engine light pop up a couple hours before but no messages or any other signs to inform me of the issue and was still working fine with no struggle until it gave out | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN | Torque Converter failure confirmed by dealer: was driving at high way speeds when I noticed a slipping sensation from the transmission upon any sort of acceleration. No warning lights were illuminated or any symptoms leading up to the failure. This could have potentially caused me to lose any form of acceleration that would enable me to get off of the highway or away from a situation requiring sudden acceleration. | Crash: No Fire: No | Unknown |
| Sep 2025 | SERVICE BRAKES | The 2021 GMC Sierra 1500 has an Electronic Parking Brake (EPB) that bolts on to the rear calipers. The EPB does not release, in order for service, you have to long press the parking brake, then the truck goes into service mode & will release the brakes for service, some newer models may not have this feature. The vehicle has 36,000 miles on it & the inside rear brake rotors are worn down from the EPB dragging & not releasing as supposed to, causing excessive premature wear & that could cause a safety hazard fleet wide. The EPB should not be in use while the vehicle is moving, but it is coded to not release, meaning whenever you press the brake it never moves back out away from the rotor, causing drag & or even can cause warping of the rotor. I do not understand the thought process in regards to not letting the EPB release, it acts like the screw type caliper that would have the same issues of every time it moves out it will not go in until taken apart & screwed in, again meaning the brake pad is constantly dragging on the rotor which could in turn also affect the miles per gallon. I see the thought process to use EPB as useful but not a good execution by the manufacturer. | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN | I have contacted local GMC repair facility (Frank Brown in Lubbock Tx.) about the safety recall on my 6.2 liter engine to attempt to schedule an inspection of my engine and cannot get them to inspect the engine which the recall notice said they would do. They continue to stall and say the inspection isn't approved by GM. I've tried 3 different times to address this isuue without satisfactory results. I recieved the GM safety recall N252494000 notice for my vehicle in May 2025 | Crash: No Fire: No | Unknown |
| Sep 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 not yet available. The contact then received a notice that parts for the recall were available. The vehicle was taken to the dealer, and the contact was informed that the recall remedy was for the dealer to use a higher viscosity oil. The contact expressed concerns that the remedy was not a sufficient repair and that the engine was still vulnerable to failure. The vehicle was repaired under the recall. The manufacturer was not made aware of the failure. The contact had not experienced a failure. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE | Engine lifters bent a pushrod and scratched my camshaft in my engine causing me to be stranded with minor children. 3rd time since I bought this in 2021 that I have had engine faults in this truck. | Crash: No Fire: No | Unknown |
| Sep 2025 | STEERING | My power steering completely failed. This is a safety issue and could have caused bodily harm. I have looked on line and I am not the only one with this issue, and as I investigated it shows that this issue was recall situation on earlier models. My truck is currently in the shop and looks like it will cost $5,000 to do the full repair. | Crash: No Fire: No | Unknown |
| Sep 2025 | ELECTRICAL SYSTEM,UNKNOWN OR OTHER | I am experiencing a recurring issue with my 2021 GMC Sierra where the dashboard displays a “Shift to Park” warning even though the vehicle is already in Park. This typically occurs when I attempt to shut off the vehicle. The doors unlock as expected, confirming the truck is in Park, but the warning prevents me from turning off the ignition immediately. After a few seconds, the warning usually disappears, allowing me to shut off the truck. This issue is more frequent in cold weather, suggesting a temperature-sensitive electrical or mechanical fault. Based on research and community reports, this appears to be a known issue across multiple GM vehicles, often linked to a faulty micro switch or wiring harness in the shifter assembly. I am concerned about the safety implications, especially if the vehicle fails to shut off properly or if the issue worsens over time. GM has not issued a recall for this problem, and I believe it warrants further investigation due to its widespread nature and potential risk. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently lost motive power. The contact was able to pull over to the shoulder of the roadway, where the vehicle failed to restart. No warning lights were illuminated. The vehicle was not taken to the dealer or an independent mechanic. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); the VIN was included, but parts were not yet available. The manufacturer was not notified of the failure. The failure mileage was 60,000. | Crash: No Fire: No | 60,000 |
| Sep 2025 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 15 MPH, the vehicle briefly jerked and jolted, prompting him to discontinue driving the vehicle. The vehicle returned to normal functionality, but the failure became a regular occurrence. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed failures with the output shaft speed sensor and the transmission control module. The vehicle was not repaired. The manufacturer was notified of the failure but provided no assistance. The failure mileage was 89,000. | Crash: No Fire: No | 89,000 |
| Sep 2025 | ENGINE AND ENGINE COOLING | See attached document for complaint. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE AND ENGINE COOLING | See attached document for complaint. I am writing as the owner of a 2021 GMC Sierra 1500 equipped with the 6.2-liter engine that has recently been included in a significant recall. I've been advised that the engine may need to be replaced entirely. As you can imagine, this is extremely concerning given the scale of the defect and the vital role this truck plays i'n my dayto- day responsibilities. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE AND ENGINE COOLING | See attached document for complaint. This law firm represents [XXX] . [XXX] owns a GMC truck with VIN: xxxxxx which is subject to the above referenced recall. Please accept this letter as Mr. [XXX] 's written complaint due to his dealer's failure to remedy the defect covered under the above referenced recall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Sep 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 not yet available. The local dealer was contacted. 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. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE | Complete engine failure on July 17, 2025, related to current recall for defective engine parts on 6.2L V8 L87 engine. Towed to dealer same day. Dealer continues to report no ETA available on replacement engine. Dealer has had possession of my unrepaired truck for 46 days now and counting. | Crash: No Fire: No | Unknown |
| Aug 2025 | UNKNOWN OR OTHER,ENGINE | Coolant control valve failure. Instantly reduces power on truck. National back order on parts. No remedy. | Crash: No Fire: No | Unknown |