Complaint volume
516 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
516 consumer-submitted complaints on record for the 2021 GMC Sierra, grouped by component category.
516 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 167
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
516 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Jul 2026 | POWER TRAIN | The 10 speed automatic transmission shakes and jumps between gears. The transmission also shakes and rumbles at cruising speeds. The diesel engine version of this truck is already recalled. My truck is a gas engine and should also be recalled. This is the same defective 10 speed transmission used in all GM vehicles and recalled in many. This vehicle needs to be recalled and fix before the wheels lock up and kill someone. | Crash: No Fire: No | Unknown |
| Jul 2026 | ELECTRICAL SYSTEM,ENGINE,FUEL/PROPULSION SYSTEM | I am submitting supplemental evidence regarding my 2021 GMC Sierra (VIN [XXX]) for Recall Query RQ26001, Campaign 25V-274. Despite multiple repair attempts, my vehicle remains unsafe and non-compliant with GM Service Bulletin N252494002. The recall remedy was performed deficiently. [XXX] Northeast Buick GMC installed a remanufactured short block instead of the required complete engine, reused the original seized-engine oil pan (which continues to leak), and failed to address critical electrical damage. Documentation proves they deleted Labor Operation 14BUZ (Engine Electrical) after their technician noted a blown mega fuse. A second dealer, Penske Chevrolet, subsequently deleted Labor Operation 77CVZ01 from my repair order, demonstrating a systemic pattern of ignoring recall-required repairs. Electrical damage has cascaded, resulting in a burnt fuse block and active faults P0615, P0617, P26E4, P26E6, U0623, and U0284. More critically, within 24 miles of my last service, the vehicle developed a new, severe safety failure: the "Service Brake Pad Monitor" system failed, accompanied by a red "Service System" dashboard alert and a noticeably spongy brake pedal. These brakes were recently serviced, yet this failure introduces a new risk of crash not present prior to the recall "remedy." GM Executive Resolution Case XXX has provided no resolution, reimbursement, or safety assurance, ignoring all deadlines since XXX. I possess extensive documentation, including service orders showing deleted labor operations and diagnostic logs. I request this update be integrated into the investigation of RQ26001, as the current remedy is demonstrably ineffective and has exacerbated safety hazards. The manufacturer’s refusal to remediate these issues, despite my compliance, leaves me with an unsafe vehicle and significant financial loss. I am prepared to provide all supporting records to substantiate this complaint. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Jul 2026 | ENGINE | I was driving and my check engine light came on a mile from my house. I drove home and the next morning, I started my truck. It was loud and pulsating like it wanted to stall out. I had it towed to a repair shop. They plugged into the truck and said it was giving code P0016. I had it towed to another place and that it is where it is sitting now. I also received a email from onstar saying "A critical issue with the engine and transmission system in your 2021 GMC sierra Crew Cab has been detected. P0016 was detected. I searched my VIN # and it says that there are no recalls on my truck. I do see that there was a silent recall on the engine that is in my truck. | Crash: No Fire: No | Unknown |
| Jul 2026 | POWER TRAIN | transmission shuddering, harsh or delayed shifting, and erratic gear changes. The truck jerks really bad during each shift of the ten speeds. A vibration or shudder typically occurring at speeds between 25-65 mph under light throttle. Also makes a bad noise every times it’s shifting. I have no lights on the dash and the gmc app tells me everything is fine when clearly it’s not . I see there’s a recall for my year and make but for some reason my vin doesn’t fall in the category | Crash: No Fire: No | Unknown |
| Jul 2026 | POWER TRAIN | My car suffered a catastrophic engine failure, metal schards were found in the oil filter and was left out of the 2021 recall 25V274. The in service date of vehicle is March 13, 2021. The car was 83 days out of warranty when the engine failed. The truck has 47,000 miles on it. They are now trying to charge us, barter with us. They have gone from $2800 for repair, negotiated down to $100 to sign this off as a good will repair stripping us of lemon law rights and future recall remedies. Car is currently sitting at the dealership. | Crash: No Fire: No | Unknown |
| Jul 2026 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while turning the ignition on, the "Service Parking Brake" message was displayed, and the check engine warning light illuminated. Additionally, the engine ran rough. The vehicle was taken to the dealer, where it was diagnosed that the engine lifters needed to be replaced; however, the dealer could not diagnose if there was further engine damage until the lifter repair was completed. The manufacturer was made aware of the failure. The failure mileage was approximately 72,530. | Crash: No Fire: No | 72,530 |
| Jul 2026 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the "Add oil to engine" message was displayed. The vehicle was driven to an AutoZone within two minutes and turned off. Upon inspection of the engine oil level, the contact observed that the dipstick was completely dry. The dealer was notified of the issue, and an appointment was scheduled for an oil consumption test. The vehicle was not yet diagnosed or repaired. The contact stated that the vehicle had been serviced for a routine oil change on April 21, 2026, at 53,590 miles. The contact related the failure to NHTSA Action Number: RQ26001(ENGINE). The manufacturer was not made aware of the failure. The failure mileage was approximately 56,802. | Crash: No Fire: No | Unknown |
| Jul 2026 | ELECTRICAL SYSTEM,ENGINE | I own a 2021 GMC Sierra AT4 3.0L Duramax (VIN [XXX]). The vehicle has codes P1098 (Coolant Control Valve Performance) and P129F which coincides with the first code. My dealer believes this is consistent with an Engine Coolant Control Valve failure. I understand Special Coverage XXX exists for this issue, but I've been told my VIN is not included. My truck has the exact engine, symptoms, and diagnostic codes addressed by Special Coverage N252508341, but my VIN is excluded. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Jul 2026 | POWER TRAIN,FUEL/PROPULSION SYSTEM | Dashboard lit up with engine light and stated that there's no compulsion | Crash: No Fire: No | Unknown |
| Jul 2026 | ENGINE | Since purchase of my 1500 Sierra 6.2L on 10FEB2021, the vehicle has always appeared to burn an excessive amount of oil which is consistent with GM’s 6.2L engines and has created safety issues leading to sweeping recalls on this engine model from 2021-2024. I have been informed that the engine was consistently down 2+ qts of oil at every recommended oil change (approximately every 5000mi) although GM literature indicated that this level of consumption was usual in their 6.2L engine. In a JAN26 oil change at approximately 35,000mi I was told that my engine was down over 3qts of oil. On 17FEB2026 I took my vehicle into my Chevy/GMC Dealership to request an oil consumption test at ~35, 089mi. On 30JUN2026 I returned to the dealership for my 2000mi check-in, at ~37,800mi, and was informed that my vehicle had failed the consumption test. With over 600,000 vehicles recalled since 2024 in the 6.2L category, my vehicle/VIN has never been associated with a recall. Despite having minimal miles on this engine, I am now financially penalized for repairs because I had just exceeded the initial Powertrain Warranty and my extended warranty would not cover a pre-existing condition. GM’s 6.2L engines have pre-existing issues from the factory and represents a danger to consumers and the driving public because of these failures. | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE | 2021 GMC Sierra after purchase at 4,700 miles had issue with the lifter rods and were replaced at that time. Now the truck has a little over 67,000 miles and once again have the same issue. This appears to be a known issue with this truck and the 5.3L engines. The truck is in repair and since it is slightly over its warranty of 60,000 miles. The dealer will not cover the repair. Seeing that this is an ongoing and known issues with service bulletins it seems that this should be a potential recall. We were lucky that we identified the issue early and were able to get to the dealer to fix. Otherwise we could have broken down in the middle of our daily commute in the expressway. | Crash: No Fire: No | Unknown |
| Jun 2026 | STRUCTURE,UNKNOWN OR OTHER | There is a water leak in the rear passenger compartment of my vehicle. Unsure where water is coming from. Continued leaking poses a risk to my safety as I may be exposed to black mold as well as anyone else who is riding in my vehicle. The problem hasn’t been addressed by the dealer yet but this is a known issue. At this point I have spoken with a representative from the service department at the dealership but cannot get an appointment for several weeks. I was also advised that the problem would need to be diagnosed before being addressed at my cost due to being outside of the warranty period. There were no warning lights or any other signs that this is occurring and was only discovered because I was putting something in the back seat on 6/26/26. | Crash: No Fire: No | Unknown |
| Jun 2026 | ELECTRICAL SYSTEM,UNKNOWN OR OTHER,BACK OVER PREVENTION | When I put the vehicle in park, the dash warning says it is not in park or shift to park. The components continue to work. I have taken it to the dealership and according to the service manger, this is a very common occurrence in these trucks. This seems to me that it would be a very serious safety issue if one assumes their vehicle is in park and it is actually not. The shift to park warning is a safety warning to alert the driver it is not in park so the vehicle doesn’t roll off and hit someone (especially a child playing in the driveway). Assuming that alert is just a malfunction could get someone killed. I did notice that this was considered a safety recall for some models of GMC vehicles but not others. I’m not sure why there hasn’t been a recall on these trucks when the service manager specifically said they are having this issue on a lot of trucks. | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE | My truck went into Reduced Power Mode while driving on the highway (Very Dangerous and life threatening) for a Coolant Control Valve Failure code (P1098), which has been confirmed by a GM dealership. GM already has extended the warranty for Special Coverage N252508341 for selective Vin numbers only and my Vin number is being excluded which isnt safe at all or fair. My truck is a 2021 Sierra Denali 3.0L lm2 duramax and has the same exact problem (coolant control valve failure code), and the same exact faulty part, and the same exact motor (LM2) which directly matches the perimeters for the N252508341 Special Coverage Program but my truck isnt being recalled or covered for repair due to them selectively choosing certain Vin numbers to recall only. | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE | While driving, the vehicle experienced a sudden and momentary loss of power, similar to briefly applying the brakes, after which power resumed. This was followed by a progressively louder squealing noise. I pulled over to investigate, at which point the engine shut off and a low oil pressure warning appeared on the dashboard. The vehicle would not restart. The vehicle was then towed to a dealership, where initial inspection suggested the issue may be related to the L87 recall involving the crankshaft bearing. | Crash: No Fire: No | Unknown |
| Jun 2026 | POWER TRAIN | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed, but the vehicle continued to move forward. There was no warning light illuminated. The vehicle was taken to the dealer and was diagnosed with transmission failure. The contact stated that the valve body and torque converter needed to be replaced. The dealer informed the contact that the transmission might need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 65,561. The VIN was unavailable. | Crash: No Fire: No | 65,561 |
| Jun 2026 | ENGINE | The AFM caused piston flapping and other major engine problems such as abnormal wear. The problem with the engine could have caused a catastrophic failure along the side of a highway. The problem has been diagnosed and the engine has been replaced at my expense. The repairs were made at a local mechanic shop. The engine would start make a loud ticking noise at 2000 RPM or above. The mechanic shop referred to this as piston flapping. This was caused by inadequate oil pressure at all cylinders due to the Active Fuel Management. | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra. The contact stated that while driving at approximately 40-45, the engine warning light illuminated. There was an abnormal sound coming from the fan. The vehicle was taken to the local dealer, where it was diagnosed and determined that the coolant flow valve needed to be replaced. The vehicle was not included in a special coverage program. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 50,000. | Crash: No Fire: No | 50,000 |
| Jun 2026 | ENGINE | My vehicle began exhibiting symptoms consistent with a failed Engine Coolant Flow Control Valve. The check engine light illuminated, and diagnostic testing indicated a fault related to the coolant control valve system. In addition, I experienced abnormal cooling system operation, including the engine cooling fans continuing to run after the vehicle was shut off. Vehicle was tested few times in Auto Zone These symptoms affected the normal operation of the vehicle and are consistent with the condition described in Special Coverage N252508341. Based on the diagnostic findings and vehicle symptoms, I believe my vehicle qualifies for coverage under this program. I respectfully request that my vehicle be inspected and evaluated under Special Coverage N252508341 and that any eligible repairs be performed according to the terms of the coverage program. | Crash: No Fire: No | Unknown |
| Jun 2026 | UNKNOWN OR OTHER | The problem is in the power-locking manual tailgate’s exterior release switch assembly. Water intrusion into the switch can cause a short circuit, leading the tailgate to unlatch while the truck is in Park. Once moving, momentum and air pressure can cause the tailgate to open further, potentially dumping cargo onto the road and creating a hazard. | Crash: No Fire: No | Unknown |
| Jun 2026 | POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM | While driving my vehicle, the engine and transmission lost power and the check engine light came on. The vehicle went into limp mode and engine propulsion was limited. Had I been traveling at a faster speed, this would have been very unsafe. After coming to a stop, placing the transmission in reverse did not move the vehicle and there was a grinding noise. I was able to savely move forward in limp mode, but the shifting was harsh. I was able to find an empty parking lot to safely park. The truck was towed to Jim Winter dealership in Jackson MI for inspection. | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the reduced power mode and Check Engine warning lights illuminated. The vehicle was taken to the dealer, where it was diagnosed with coolant control valve failure. The contact was informed that the coolant control valve needed to be replaced. The vehicle was not repaired. The contact was informed that the failure was like the failure description in Special Coverage Bulletin: N252508341. The manufacturer was made aware of the failure but provided no assistance. The contact was informed that the VIN was not associated with the Special Coverage. The failure mileage was approximately 58,500. | Crash: No Fire: No | 58,500 |
| Jun 2026 | POWER TRAIN | When pressing on the gas, especially when moderately accelerating, the truck experiences severe shaking, which interferes with acceleration, as well as causing the truck to "jump" when the transmission gear "catches", even while driving. When the truck is at a full stop and the engine is auto off, when it restarts, it does so frequently when it reengages that it causes a physical "jump" in the vehicle, causing the driver's foot to come off the brake pedal. This has been most noticeable since my vehicle hit about 70k miles. I currently have 84k miles. I engaged the dealer and was told the transmission is out of warranty. I see that other GMC Sierra models suffer similar problems and recalls have been issued to GMC that they must repair those vehicles. Despite that, my vehicle is not included in any current recall program. | Crash: No Fire: No | Unknown |
| Jun 2026 | POWER TRAIN,ELECTRICAL SYSTEM,FUEL/PROPULSION SYSTEM | So I made an appointment to have my truck recalled and the Wednesday before I took it, and it cranked no start and I called the dealership. Ask if they had any other those like this and they said that it could be the fuel injector module and so I got it to a mechanic shop to read the codes and it gave me a code p062b and I asked the dealership to look into it and they never figured out what we were not wrong. I just testing the battery. Well, then I got it back after the recall was done and new transmission valve body put in and about 30 miles down the road it started to shake violently and had a flashing engine light so I got it home called the dealership the next morning because they were closed set up another appointment got it to the dealership dealership said it had a couple misfires but since it wasn’t over 100 they weren’t concerned even though I’m pretty sure it is related to the fuel model going out because it has been cranking rapidly whenever I try to start it, but they won’t do anything to figure out what’s wrong? | Crash: No Fire: No | Unknown |
| Jun 2026 | ENGINE | Engine Coolant Control Valve Position Sensor Minimum Stop Performance, and Chevy recalled this on this same motor and GMC needs to pays for this as it’s a major problem! | Crash: No Fire: No | Unknown |