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 2025 | POWER TRAIN,ENGINE | Engine has stopped a couple of times at low speeds, Was able to restart and continue. Engine will occasionally make a "straining / Dieseling sputtering sound" when execellerating from low speeds or Stop. Transmission will make strange and strained shifts from time to time. This is reaccruing problem that comes and goes over the last approximately 2 yrs since about 9000 miles to current approx 25000 miles. | Crash: No Fire: No | Unknown |
| May 2025 | LATCHES/LOCKS/LINKAGES | The contact owns a 2021 GMC Sierra 1500. The contact stated that the rear tailgate panel buttons had deteriorated causing water intrusion into the panel, and the buttons became inoperable when pressed, and the rear tailgate would not open. The vehicle was taken to the local dealer who replaced the rear tailgate panel, and the vehicle was repaired. The manufacturer was notified of the failure, but no assistance was offered. The failure mileage was 20,000. | Crash: No Fire: No | 20,000 |
| May 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal rattling sound coming from the vehicle, with several unknown warning lights illuminated. The vehicle was driven to the residence. The vehicle was taken to the dealer where it was diagnosed with cam shaft and lifter failures. The contact was informed that the cam shaft and the lifters needed to be replaced. The vehicle was not repaired. In addition, the contact stated that when the vehicle was purchased in 2020, the failure had occurred; however, the repair was covered under warranty. The manufacturer was not made aware of the failure. The failure mileage was approximately 7,000. | Crash: No Fire: No | 7,000 |
| May 2025 | ENGINE | code P1098. Engine light comes on, power is reduced, coolant fan runs on high. Temp gauge fluctuates. This last for 20 minutes or so. The engine then returns to normal. After a few days the engine trouble light goes off. This happens every several weeks. Parts are backlogged and I understand this is a common problem with this engine. I have 64000 on it. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | The transmissions in this as well as several other models of GM as well as Ford products with these transmissions are known to have major issues. My particular vehicle has major transmission shipping issues that started right around 90,000 miles or so. It started with a hard shift occasionally and has now progressed to a consistant hard shift, as well as a major shudder issue in the 35-45 mph range as well as the 65-75mph range ( when shifting into applicable gears) this has gotten worse over the last few weeks. These GM/Ford collaboration transmissions have been faulty from their inception and are well known to start malfunctioning in the 80-120,000 mile range. Please recall these transmissions so that consumers are not faced with thousands of dollars in repairs in vehicles that should last well beyond the short life span of the transmissions. I have been quoted 62-6500.00 for a replacement as there is no rebuilding these transmissions according to the mechanics I have consulted...(some have cited part availability issues as a reason). This has been a well reported problem with these vehicles/ transmissions for years now with many complaints and issues about the faulty transmissions. Just google it. I don't understand why theu have yet to be recalled. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | While driving vehicle started running rough and exhaust was white from tail pipes, could not accelerate and warning lights were flashing. Limped to dealership and diagnosed with a bent rod and had to tear both sides of engine apart and replace heads on both sides due to bulletin for Gmail at 7500 miles. Why is this vehicle not part of the recall to protect my investment? | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | While the vehicle is traveling at highway speeds it is misfiring and sputtering, giving the feeling of a hard shift. When the vehicle is idling, the engine is sputtering like it’s going to shut off. If the truck were to shut down, as it seems to be trying to do, this could be deadly at highest speeds or intersections. The vehicle has been at a dealer since January 2025. They claimed to have fixed it but upon paying over $1200 and picking it up from the dealer, the problem persisted. We had to take it back to the dealer within 5 minutes of picking it with zero repairs and no estimated time of repairs ever since. No warning lights appeared at all. | Crash: No Fire: No | Unknown |
| May 2025 | ELECTRICAL SYSTEM | GM has has a known issue with a switch/sensor placed at the base of the shifter that causes the “shift to park” error message that prevents the electrical system from shutting down when the vehicle is physically in park and the engine is turned off, In fact, GM has issued a recall for several different models in which a “shift to park” error message is displayed because of the poor design; however, they continue to see the same issue occur but claim it is not a warranty issue (unless it occurs within 3 year/36,000 mile time frame. This is not an issue that can be caused by owner misuse, and I believe that GM should be held liable for repairs given that the issue is, and has been, known for several years now. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | So there is recall already for the engine but I’m not part of it which is weird cause my engine has been acting weird which I’m trying to take to dealer ship but they don’t want it due to I not being in the recall list. I have the engine 6.2 LTI have an 2021 GMC Sierra Denali | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | VEHICLE IS DIAGANOSED WITH A COOLANT CONTROL VALVE ISSUE. VEHICLE IS CURRENTLY AT A GM DEALER AWAITNG REPLACEMENT PART AND PART IS ON BACK ORDER FOR AN UNDERTEMINED AMOUNT OF TIME. IT IS WIDELY KNOWN THIS IS A COMMON PROBLEM WITH THIS MAKE AND YEAR MODEL OF VEHICLE. THIS MATTER PUTS AN UNDUE HARDSHIP ON ME AS A VEHICLE OWNER. WITH NO KNOWN ETA FOR THIS PART I STAND TO BE OUT OF USE OF THIS VEHICLE FOR A LONG TIME. GM NEEDS TO BE MORE ACCOUNTABLE AND ATTENTIVE TO THEIR CUSTOMERS AT A TIME LIKE THIS. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,VEHICLE SPEED CONTROL,FUEL/PROPULSION SYSTEM | The engine coolant flow control valve position sensor is faulty. I brought mt truck in to my dealership and I have been waiting for over a month to get the issue fixed because “the part is on backorder”. This issue makes my truck sound like a jet engine because it makes the truck think overheating and causes the fan to come on at full blast. After drivinf for awhile it goes into “ reduced engine power mode” which is totally unsafe because it reduces the horse power to that of a lawn mower. It takes about 30 seconds to get from 0-60, so merging onto freeways or in conditions where you need extra speed its completely useless and increases the scenario of being rear ended, immensely. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | The camshaft cover in pre 2021 3.0L Duramax motors is leaking oil/def internally causing oil loss. This is something GM has noted in their TSB pages but has not issued a recall over. This is a hazard to emissions, oil consumption, and the def system. Also could result in premature engine failure. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | -While driving the vehicle on the highway, abruptly lost power and RPM. Check engine light, along with multiple other warning lights lit up. When parking the truck soon after, had an associated rough idle with low RPM. The truck was then towed to GMC dealership. -Multiple fuel injectors failed, starting misfiring and caused damage to the engine. Unknown if previous injectors are available, replaced at GMC dealership. The damage resulted in recommendation to replace the engine. -Engine began misfiring while traveling at highway speeds, placing me at an increased risk of loss of control of the vehicle. -The problem was reproduced, confirmed, and inspected at a GMC dealership. -No warning lights or symptoms were present prior to accident. Incident occurred abruptly. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 75 MPH, the vehicle lost automotive power. The contact pulled over onto the side of the road, and upon parking on the side of the road, the message "Shift to Neutral" was displayed. The contact shifted into neutral, and the vehicle was restarted. The vehicle was taken to a local dealer, and was diagnosed, and the contact was informed that no cause for the failure was found. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 24,453. | Crash: No Fire: No | 24,453 |
| May 2025 | POWER TRAIN,ENGINE,LANE DEPARTURE | El motor de mi camioneta falló por completo empezó a hacerle unos ruidos muy fuertes dentro del motor con solo 80,000 millas es del 2021 la compré el año pasado no llegó ni un año de uso una camioneta que supuestamente era muy buenas Estaba en el momento de lo sucedido estaba con mi mujer y mi hijo en el auto regresábamos de un restaurante acá en Miami y la camioneta se paró de pronto La camioneta fue inspeccionada por la garantía extendida la cual no asumió la reparación Luego del problema si salieron luces amarillas y rojas en la pantalla de mi camioneta | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | In February of 2025 my check engine light came on while i was at work. Went to the local auto zone to have the code read and it. Right after that i drove straight to Gay Family Auto. along the way there was a jolt followed by a stall The car behind me nearly re ended me. i made it to the dealership after inspection i was told i blew a rod and had metal shavings due to an engine failure. Up to this point i had no indication of any issues or dash board warnings. i was told i needed to provide all prof of oil changes which i did. after two months i get my truck back from GMC with a new motor. The new motor is now under recall for doing the exact same thing as my old motor. GM basically took out a faulty motor replaced it with a new one in hopes nothing happens. I reached out to GM and they told me to take it to a dealership for inspection. The dealership told me they wont touch it til GMC sends a solution. im currently driving a truck that could possiably fail again | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ENGINE | While driving on the highway the engine died forcing me to change lanes to cross traffic and coast to a stop on the shoulder. It was dangerous and unexpected. It would not restart so I had to have it towed. Inspection revealed the bearings had gone bad in the engine and the engine would have to be replaced. I had to wait 2 and half months for an engine. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2021 GMC Sierra 1500. The contact stated that the vehicle was experiencing excessive oil consumption. The low oil pressure warning light was illuminated. The vehicle was taken to the dealer, but the failure could not be duplicated. The vehicle was taken to the dealer several times, where an oil consumption test was performed. The contact stated that the oil consumption test was not completed. The contact stated that while driving 55-60 MPH, the contact noticed an abnormal oil odor, and the low oil pressure warning light was illuminated. The contact pulled over. The contact then noticed that a significant amount of oil was leaking onto the ground. The vehicle was towed to the residence of the contact's brother. The contact stated that upon inspecting the vehicle, the contact became aware that oil was leaking from the oil pan. The vehicle was towed to the contact's residence, where the contact added oil to the vehicle. The vehicle was taken to Beck & Masten GMC Coastal (200 US-77, Robstown, TX 78380), where the rear main seal gasket was replaced; however, the failure persisted. The vehicle was taken back to the dealer, where it was diagnosed that the alternator and the crankshaft hoses had failed due to excessive oil leaks. The dealer charged a fee for the alternator and the crankshaft hoses replacement. The dealer informed the contact that the rear main seal gasket replacement was covered. The dealer related the oil leak to the oil pressure. The vehicle was not repaired. The manufacturer was notified of the failure, and cases were filed; however, no further assistance was provided. The failure mileage was 44,000. | Crash: No Fire: No | 44,000 |
| May 2025 | ENGINE | The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the vehicle lost motive power, with several unknown warning lights illuminated. The vehicle was able to restart but went into LIMP Mode. The vehicle was towed to the dealer, where it was diagnosed that the cylinder head had failed and needed to be replaced. The vehicle was repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The approximate failure mileage was 43,000. | Crash: No Fire: No Towed | 43,000 |
| May 2025 | STEERING,WHEELS | I was driving approximately 25-30 mph coming over an overpass moving into the right hand lane when my truck right front end failed. The steering and brakes locked up for approximately 50’ until I hit the curb for the sidewalk and stopped. I safely exited the vehicle checked the left side of my truck for damage and didn’t find anything. I walked around the back of my truck and came to the passenger side where I found my right front wheel and tire completely broken away from both upper and lower control arms, the ball joint broke and failed as well as the brake line. If I was driving on the highway at 65-75 this catastrophic failure could have resulted in a fatal collision. The night before my [XXX] daughter and I returned from her outdoor Ed trip in Sausalito and we drove an hour home to Napa on [XXX] and [XXX] . I thank god this didn’t happen with her in the car on the highway. I had my truck towed to Jimmy Vasser Chevy in Napa so I can see if the extended warranty will cover the repairs since it was an obvious catastrophic failure of the whole right front end. It’s still sitting there. The extended warranty inspector came Friday to take pictures of the damage INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: Yes Fire: No Towed | Unknown |
| May 2025 | POWER TRAIN | Was driving vehicle on freeway at normal speeds and the vehicle lost propulsion. Engine was off and vehicle said to shift to neutral and restart. I was able to exit the freeway safely (barely) to the median. Vehicle would not restart. It has the L87 engine which is under recall. Vehicle is at dealership submitted under the recall. I am being told there is "no remedy" and "no parts" and given no timeframe for any fix to be completed. I am still liable for the payments, insurance and this is our only vehicle in a single father of three family. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | The vehicle will crank and not start. Dealership said they cannot replicate the fault. Same problem occurred after with dealership not helping. I am a US Soldier currently stationed in Germany and continue to have the same problem every 2months. It will crank and not start. The truck will start on the second attempt after cranking for about 20seconds. The continued issue can permanently damage expensive repair parts that I will not be able to afford. I know I am not the only one with the same issue as I have talked to others and have no solution for this. | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER,ENGINE | We NEVER RECEIVED A RECALL NOTICE FYI . This vehicle has been serviced consistently.never an issue. Driving on [XXX] very busy! Truck literally stopped in the middle of the freeway in a very bad location. Desert. Noon. Kids with us. Could have died. Preliminary eval: engine seized, piston rod failure. Not sure the rest - we have to tow it home first. Failed while traveling. Please call for more information if needed. [XXX] [XXX] 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,ENGINE | I was coming home after work, before I got home I stopped at the gas station to fill up my tank, after I filled up my tank I start driving home but while on my way home my truck wasn’t speed as I expected and it only goes maximum of 10mph and I was confused, I stop and check my truck see what happens but there is no sign since there was no sign I get on my truck and start driving to home, after I got home I was trying to revers parking and that’s when I realized my truck wouldn’t reverse. I thought of if it happened while I was driving on highway and my truck stopped on the middle of highway I could have lost my life. I called the dealer and the dealer told me it might be because of the engine then next day I took it to the shop and they couldn’t figure until couple days later and it took them around 2-3 weeks to replace my transmission. Luckily I had the power train warranty when I bought the vehicle and it don’t cost anything. If I didn’t have that power train warranty everything will come out of my pocket, the cost was around $6-7k. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | Coolant Control Valve (ccv) on these vehicles are notorious for breaking down/ becoming non-operative. I have been waiting for a part for months. | Crash: No Fire: No | Unknown |