Complaint volume
484 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
484 consumer-submitted complaints on record for the 2021 GMC Sierra, grouped by component category.
484 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 155
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
484 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Mar 2026 | ENGINE,FUEL/PROPULSION SYSTEM | Engine developed a low knock type noise just above idle while beginning to move in the parking lot. It was also noted pulling away from an intersection at low rpm under light acceleration. Oil pressure was normal, 30 psi and approximately 50-60 at cruising speed. Low level knock began earlier in the day but no other symptoms. Oil level was checked and found to be at proper level. At mile 2 into my trip a chirping/ squeak type noise was heard under light throttle and light load at approximately 1500 rpm. The noise stopped when accelerator was released. Rough running sensation followed the noise under the load. Noise returned when the accelerator was pressed and then the engine stopped running while traveling 45-50 mph. Placed the shifter to neutral and attempted to restart, engine rolled slowly for a brief moment and then locked up entirely. Starter only clicks when attempted after that. Vehicle left me stranded with no heat on the shoulder of the highway in the dark in Northern Michigan on March 5, ambient temp was 28 degrees. Vehicle towed to closest dealership which is also where it was purchased for inspection on 3/6/2026. General motors customer care contacted and case opened. No assistance with repair at time of callback. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN | With the cruise set at 55-60 mph the Rpms will jump, along with a slight shudder feeling. Cruise control has turned off a few times due to this. Cruise set at 25mph and would shudder/lunge forward. Torque converter is showing it’s slipping and will need replaced. No check engine lights. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN | Per GMC dealership, this vehicle suffered a Transmission valve body failure and they are recommending replacement of the entire transmission. | Crash: No Fire: No | Unknown |
| Mar 2026 | POWER TRAIN | My vehicles transmission is part of a recall but my vin is not registered for this recall repair. Please assist. | Crash: No Fire: No | Unknown |
| Feb 2026 | POWER TRAIN | Engine coolant control valve failure. This is a widespread issue on 2020-2022 3.0L Diesel trucks and it hasn’t been addressed by GM, leaving owners to pay out of pocket for a faulty part. | Crash: No Fire: No | Unknown |
| Feb 2026 | POWER TRAIN | Vehicle began to slip or shift hard when putting it in gear or coming to a stop. The next morning the vehicle would not move when put in drive or reverse. | Crash: No Fire: No | Unknown |
| Feb 2026 | POWER TRAIN,ENGINE,BACK OVER PREVENTION | I was driving on a highway on my way home from work. Thank god there was not a lot of traffic because my truck just shut off lost all power, then I received a message on the dash to put on neutral and restart. I tried multiple times to turn it back on. It never turned on and had to get it towed to nearest dealership. It took them a week to inform that the engine locked up even though I tried to take it for the recall they told me to wait and reschedule the appointment. Never got a new appointment until the engine failed and I got it towed to the dealership and have also not received a new kind of loaner from GM. This will be my last GMC truck I purchase. | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that while operating the vehicle, the check engine warning light illuminated and remained illuminated. While driving at various speeds, the vehicle entered LIMP Mode, causing the vehicle to decelerate. Additionally, the radiator fan was continually activated while operating the vehicle. The vehicle was taken to the local dealer, who diagnosed that the coolant control valve was inoperative and needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure, but no assistance was offered. The failure mileage was 119,000. | Crash: No Fire: No | 119,000 |
| Feb 2026 | ENGINE | The failed component is the engine coolant control valve on a 3.0L Duramax truck. The failure has been documented and confirmed by both an independent mechanic and an authorized dealership. The malfunction creates a significant safety hazard. Without warning, the truck will suddenly enter a reduced engine power mode while traveling at normal highway speeds. When this occurs, the vehicle will not allow acceleration beyond approximately 50 miles per hour. This is especially dangerous when operating on roadways with speed limits of 70+ mph, as the sudden and unexpected loss of power places myself and surrounding motorists at risk. The problem has been reproduced and confirmed by Steele GMC in Round Rock, Texas. In addition, the vehicle has been inspected by an independent mechanic, both of whom verified the coolant control valve failure. Prior to the initial occurrence of the failure, there were no warning signs. Once the malfunction occurred, the check engine light illuminated. General Motors has issued Service Bulletin #25-NA-185 (revised December 4, 2025), which addresses engine coolant control valve failures on 3.0L Duramax vehicles and outlines the proper diagnostic and repair procedures for this exact failure mode. This bulletin applies to 2021–2026 3.0L Duramax trucks. Additionally, GM has implemented Special Coverage program N252508341 for 3.0L Duramax coolant control valve failures, which extends coverage up to 15 years or 150,000 miles when diagnostics confirm the failure condition. Despite the fact that my vehicle’s documented failure matches the exact conditions described in the above-referenced service bulletin and special coverage program, I was informed by Steele GMC that my specific VIN is not included in the warranty. Given the documented safety risk, the confirmed diagnosis, and the existence of official GM guidance addressing this precise issue, I respectfully request this be reviewed and appropriate coverage or corrective action be authorized | Crash: No Fire: No | Unknown |
| Feb 2026 | POWER TRAIN | I have had shuddering on the highway and a few hard random diwnshifts. Last week I went to start my truck and the transmission started grinding and rattling. I was told after towing to the dealer it needed a transmission due to pump not getting enough fluid and had failed. I was told I needed to pay, even though the part causing the problem had a extended 150,000 miles and the subsequent pump failure is a result of the control valve failure. | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE | Had a P1098 code. The truck was diagnosed by a certified technician. Found to have a failing coolant control valve. GM has issued special coverage for this known failure. Special coverage is not including the VIN for this truck although it falls in the criteria for model, year, and engine model. | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE | Engine failure without any warning. Car maintenance was kept up-to-date. | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE | At 22,000 miles I experienced issues while driving on a 150 mile trip. We frequently take this particular drive. We choose to driver later in the evening to miss commuter traffic. This even we pull over for a late dinner and hear a loud ticking noise while the the truck seems to lose power. I turn the vehicle off and start it again and its worse, it barely idols and shuts down. I'm in a parking lot and drive down the block to a gas station where serves only gas and no mechanics onsite. I turn off the car and wait 5 mins and restart, same results but this time all the warning lights come on. We end up finding a hotel and in the morning i find a Chevrolet dealership down the block, I ask if I can take it in, there the advisor connects to my obd port and says there are many issues and needs to see a mechanic. I manage to get it towed 80's to the original dealership. Advisor says the engine is bad and replaces it. Now my vehicle has 38,000 miles and I run into the same issue, loud ticking sounds and low power. Immediately I drive it home and the next day have it towed to the dealership to have it looked at. The advisor said during their analysis they saw metal in the air filter so another engine has to ordered and installed. | Crash: No Fire: No | Unknown |
| Feb 2026 | POWER TRAIN,ENGINE | The engine has been burning oil since purchased but really highlighted when at 47k miles I got a dashboard message saying “reducing power to engine” I checked the oil and it didn’t register in dipstick. I added 3quarts of oil to show up on dipstick. When I changed the oil which I did at my own garage only 2.5qrt came out including what was in filter. It’s since take an average of 2.5qrt between oil change at 7500. Also the transmission is slipping which happened after warranty expired at about 69k miles and I don’t want it to repair or repair until gm fixes these issues which they know are problem in2020-2021 models but they haven’t addressed it. My truck has been serviced at the dealership except fo 3 oil changes. The issue are noted but the answer is car burn oil typically between changes. Yeah they do if it was 20yrs old not 3yrs. The issue lies with GM. It’s Needs to be addressed. | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE | Loss of power code p0016 now truck won't start | Crash: No Fire: No | Unknown |
| Feb 2026 | ENGINE | Burns excessive amounts of oil between oil changes.All cars were covered under the g.M recall mine fell, one month behind.But this motor is the exact motor that has been recalled to put in a heavier weight oil.Please expand the recall.So my truck can go in. | Crash: No Fire: No | Unknown |
| Jan 2026 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 65 MPH, the vehicle was shaking abnormally with the check engine warning light illuminated. The contact pulled over to the side of the road and had the vehicle towed to the residence. The contact referenced NHTSA Campaign Number: 25V274000) (ENGINE AND ENGINE COOLING) as a possible cause for the failure. A dealer was not contacted. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was 66,456. | Crash: No Fire: No | 66,456 |
| Jan 2026 | ENGINE | The oil consumption is abnormal and burns almost 2.5 to 3 quarts between oil changes. This can be a heavy risk to the engine if I don’t check on it every couple weeks. I don’t think after the price I’ve paid for this truck that I should have this concern and this should not be the case | Crash: No Fire: No | Unknown |
| Jan 2026 | POWER TRAIN,WHEELS | 4 months after bring my truck back to the dealership for a body valve issue on the 10 speed transmission. The truck went into limp mode while I was driving. | Crash: No Fire: No | Unknown |
| Jan 2026 | ENGINE | My 6.2 engine locked up and left me stranded. Had it replaced with s new engine on 10/31/2025 and I'm having problems again with it. As well as my 10 speed transmission slipping and hunting for gears | Crash: No Fire: No | Unknown |
| Jan 2026 | POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM | On the afternoon of 01/20/26, I was merging onto the highway in my 2021 GMC Sierra 1500 when a loud bang was heard from the engine compartment at approximately 60 mph. Immediately after the ban was heard, several indicator lights on the dashboard were illuminated, including the ESC, check engine light, and parking brake light. A power loss was felt when attempting to accelerate and the banging noise worsened anytime the accelerator was depressed. I was able to drive the vehicle to the nearest GM dealership that coincidentally was at the closest exit off of the highway I was traveling on. The dealership performed diagnostic and determined that the damage was caused due to the ongoing GM recall associated with Safety Recall N252494000. My vehicle had previously been inspected as part of the recall and was found to have passed. Vehicle had been driven approximately 4,000 miles after recall was performed. | Crash: No Fire: No | Unknown |
| Jan 2026 | POWER TRAIN | 1-At approximately 40,000 miles, my transmission was replaced under warranty. It had been failing since approximately 2000 miles having a very hard time shifting between first and second gear. It was finally replaced at 40,000 miles. 2- At approximately 45,000 miles I took my truck into the dealership for this latest recall on the 6.2 L failure for inspection. Vehicle is inspected and I was told I would need to have an engine replacement. I was told that there was no ETA on when a replacement engine would be available and that I would be contacted when one was. Afterwards I was sent back home in the truck they just inspected for potential engine failure and said had a bad engine. As of now, I’m still waiting on a word of a new engine and my truck is still operating, but leaves me concerned that it could fail at any moment while driving it. | Crash: No Fire: No | Unknown |
| Jan 2026 | ENGINE | The engine has a knocking sound. I took it into the dealer and they replaced the exhaust system thinking that was the problem. However, the knocking still happens intermittently. I have video documentation of the noise. | Crash: No Fire: No | Unknown |
| Jan 2026 | ENGINE | There is an active recall for the 6.2 L engines, which is what I have and it’s an issue with burning oil and catastrophic engine failure due to rods and bearings. And I just got this vehicle in November and I have already went through 15 quarts of oil in two months so I’m waiting for my engine to blow up going down the road to cause a wreck like has happened to multiple vehicles already and I also have a rod knock now due to this issue so it could be any time now that my engine fails and I end up getting hurt or my family I took it to the Chevy dealership and I have called GM to do an oil consumption test and to put in a claim so that way if it does fail, then it has paperwork to follow, but it is a major safety concern but something needs to be done considering there’s already 600,000 recalls on this issue already there needs to be more for the rest of the people that are having this issue like myself and I’m spending $50,000 on this truck for the engines to fail and me end up dying before something‘s done. and it’s also very distracting as you’re driving down the road and your vehicle tells you that you’re low on all so you have to try to find a way to get off the highway to have someone bring you all so you can continue to drive and it’s not just a cordial. It is up to 5 quarts of all at a time. | Crash: No Fire: No | Unknown |
| Jan 2026 | ENGINE | For the second time since I have owned the vehicle that was purchased brand new. The engine seized during driving on the highway and began making loud noises that was knocking and jerking the vehicle. The issue occurred initially around 15,000 miles and was diagnosed as lifter failure, was repaired and returned in July 2022. At 64,000 miles on January 15, 2026, while on an interstate the engine did the same thing and the vehicle went into limp mode. It has been diagnosed as lifter failure this second time and is awaiting appropriate repairs. Both incidents put myself in passengers at danger due to the nature in which the vehicle entered limp mode on the highway. | Crash: No Fire: No | Unknown |