Complaint volume
436 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
2020 GMC Sierra Complaints
436 consumer-submitted complaints on record for the 2020 GMC Sierra, grouped by component category.
436 Total complaints
11 Crash reports
5 Fire reports
6 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, electrical system. Use those categories as a test-drive checklist instead of judging the vehicle from the total count alone.
Severity flags
Enriched records include 11 crash reports, 5 fire reports, 6 injury reports, and 0 fatality reports. These fields come from complaint records and should be read in context.
Mileage clue
Mileage is available on 121 complaints, with an average reported failure mileage of 45,188 miles. Compare that with the mileage on the listing.
Questions to ask the seller
- Have you had any problems related to engine, power train, electrical system?
- 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 2020 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.
2020 GMC Sierra
Build buyer checklist Compare with other years Sends year, make, and model to pre-fill your checklist.
How severe are the 2020 GMC Sierra complaints?
11 Crash
5 Fire
6 Injury
0 Fatality
29 Towed
4 Medical attention
What are the most common 2020 GMC Sierra complaint categories?
ENGINE 130
POWER TRAIN 38
ELECTRICAL SYSTEM 22
POWER TRAIN,ENGINE 17
SERVICE BRAKES 16
STEERING 14
UNKNOWN OR OTHER 14
ENGINE AND ENGINE COOLING 10
SUSPENSION 9
ELECTRICAL SYSTEM,ENGINE 8
436 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Jun 2025 | STEERING,ELECTRICAL SYSTEM,ENGINE | Loss of power steering. Loss of engine propulsion at high rates of speed. Engine would not start. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN,ELECTRICAL SYSTEM,ENGINE | Hi I have always taken good care of my 2020 gmc Sierra 1500 at4 6.2 Kept up with its regular and recommended maintenance. I had no warning signs on the dash. So it surprised me that while on my way to work early one morning I was getting off the highway exit and the truck lost power, my steering wheel hardened and it posed a great threat to my life and others on the road, as it suddenly decelerated in a area where people are driving at accelerated speeds. The whole truck was loosing power and shaking hard as I attempted to steer it to a safe location on the side of the road. Had a mechanic inspect it and they determined The truck ended up with a seized engine. I have since not been able to use my truck for 8 months and still currently paying monthly payments of 1000 to pay it off. | Crash: No Fire: No | Unknown |
| Jun 2025 | SUSPENSION,ELECTRICAL SYSTEM,WHEELS | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 60 MPH, the horn failed to function as intended. There were no warning lights illuminated. The contact stated that on a separate occasion, the right lane sensor stopped working as intended. There were no warning lights illuminated. The contact stated that on a separate occasion, while driving 60 MPH in the rain or on rough asphalt, the rear suspension caused the vehicle to fishtail to the right. The contact turned to the left to control the vehicle. The contact stated that the vehicle returned to normal functionality after the failure. The low transmission fluid warning light was illuminated. The vehicle was taken to an independent mechanic, who diagnosed the vehicle with an electrical systems failure. The independent mechanic informed the contact that there was adequate transmission fluid inside the transmission, and it was unclear why the warning light was illuminated. The contact was informed that weights were added to the wheels to balance each wheel. The vehicle was not yet repaired for the other failures. The contact stated that the transmission was replaced a year prior to the failure, and the horn had failed to function soon after the transmission replacement. The manufacturer was made aware of the failure. The failure mileage was approximately 68,000. | Crash: No Fire: No | 68,000 |
| Jun 2025 | POWER TRAIN | I am reporting an ongoing safety issue with my 2020 GMC Sierra 2.7L related to the transmission. On two separate occasions within the same month, my truck broke down in the middle of the street, requiring it to be towed to the dealership for service. The first time, the dealer informed me they repaired a part inside the transmission and stated the truck was fixed. However, after picking up the vehicle, the issue persisted, though not as frequently. When I called them, they advised me to drive it for another 100 miles so the valve could fill with oil and the transmission could properly recalibrate. After a few days of driving, the same issue occurred again — the truck stalled in the middle of the street, and I had to have it towed once more to the dealership. This time, the truck remained at the dealer for about a week. They replaced another part inside the transmission and returned the truck to me, noting that it only had about 40 miles of warranty remaining. I asked the dealership to extend the warranty or give me at least two months to test the truck and confirm the issue was resolved, as I am genuinely concerned for my safety and my family’s safety if the vehicle breaks down again on the road. They told me they would respond within two days, but it has now been over 10 days with no response. I am currently afraid to drive the vehicle because of the risk of it breaking down again, especially with my family inside. I am requesting that NHTSA review this issue for potential safety concerns with the transmission system in this vehicle model. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | Lifter failure at around 102-103k miles, was doing a random misfire and transmission studder ( due to the dfm system activating, cutting down cylinders to save fuel while driving, this was happening since approx 59k miles, dealership and gm was aware of it and they said it was normal, but that normal misfire turned into a failed lifter causing misfire and studder. I ended up replacing the lifters myself put solid lifters and a new camshaft that would eliminate the dfm system and studder, ran good no studder and random misfire, and now my crankshaft or oil pump is bad which I will remove motor to furthermore inspect. I’ve read forums and stuff where people would get a lifter job done and then soon after couple thousand miles later the motor goes bad. The 5.3 motors have bad crankshafts, oil pump and lifters just like the 6.2lt motors. After the lifter and cam repair, it ran good for couple thousand miles shortly after My gmc threw an “oil pressure low turn off vehicle code”, turned off vehicle immediately and checked oil, verified oil was good. Gm will not cover it because of it being way out of warrenty when I had issues with random misfire around approx 70-78k miles, and to note that my cat converter went back when lifter failed aswell. Also to note that when the lifters fails it throws a speed reduced to 55 mph, traction off, steering assist reduced, and brakes reduced, this is a safety hazard and also it will drain the battery and cannot start it if you pull over on the side of the road and turned it off and on again to make it back home. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | Misfire alerts causing major motor repairs | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | My 5.3 engine spun a bearing on the crank. Same exact problem the 6.2 got recalled for. Now if I put a used engine in it’ll cost me around $6,000. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | TRANSMISSION SHURTTING, JERKS, AND VIBRATION, BAD TORQUE CONVERTER BUBBLE AND PELLING PAINT. IT FEEL LIKES ENGINE IS LOSSING POWER | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER,ENGINE | 6.2 liter engine fail- replaced at new cost, 20,000 miles later another 6.2 engine failed. unable to get new engine due to GMC finally recalling the engine. My VIN is not included in the recall. I now have no vehicle to drive but still have a loan to pay. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | Driving at freeway at 65mph, suddenly is air noise like air conditioning blows air at high fan speed, than the dash info shows (Engine Power is Reduce) try to accelerate to pull out of lanes, and it did not, keep losing speed, as slowly move lanes to the right of freeway, and then exit.. This is the second time of this incident, first time under warranty, dealer fix transmission first time, then two months later, the tansmission was replace wit a newone, now is passed warranty, had the car taken to dealer, they gave me and estimate of more then $10,000 to fix the vehicle, this happen on May 21, 2025... | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | Transmission valve control malfunctioned, causing rear wheels to temporarily lock, skidding the tires. This almost caused me to loose control, endangering myself and others around me. This is the second time this problem has happened. A recall related to this was addressed on this truck, though it has clearly done nothing to prevent it from happening. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | Transmission valve control system malfunctioned, causing rear wheels to lock up at high speeds, in turn causing tires to skid out. This issue almost caused me to loose control of the vehicle, potentially endangering the safety of myself and others near me at the time. This is the second time this has happened while I have been driving this vehicle. There was a recall related to this issue, which was addressed, but very clearly did absolutely nothing to prevent this incident from occurring. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ELECTRICAL SYSTEM,ENGINE | Engine light would come on for a few days and than turn itself off. this occurred for about 8/9 months; however, instructed by the GM Maintenance department that if the vehicle came in and the light turned off before they got to it i would be charged for the diagnosis and no work would be performed. Engine light came on and i was able to park the vehicle / they picked it up and read it prior to putting in their lot until a tech became available. GM Maintenance was able to diagnosis that there was an issue with the EGR sensor and NOx catalytic converter without filter failed / both items replaced | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ELECTRICAL SYSTEM,ENGINE | Vehicle Stuck in gear. Dealership was delivering the car back to myself when about a mile out from my house when the vehicles made a sudden downshift and was stuck back in gear. Driver called and notified me that it was on its way back to the shop for further work | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ELECTRICAL SYSTEM,ENGINE | Engine light came on and real bad urine smell / burning coming from the vehicle / rough performance. This issue occurred at various speeds / trips / drive types with the only variation being speed from 25MPH to 75MPH. Vehicle went in to discover that the reductant control module software (RCM) out of date, and two NOx sensor failures | Crash: No Fire: No | Unknown |
| May 2025 | ELECTRICAL SYSTEM | While driving my vehicle it began down shifting harder than normal (at various speeds and road (highway, city and dirt road)); along with a noticeable burning smell after every trip. GM Maintenance personnel discovered that the wire was chafed and arching / catching on fire underneath passenger side resulting in the burning smell and the wiring issue aligned to the transmission. Personnel took a video and provided to me as evidence of the fire / smell; however, that was on their official GM app so i was unable to download | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER | Engine light came on while driving / aligned to transmission temp sensor error and brake sensor GM Maintenance was able to diagnosis that the Temperature Loop Coolant Pump had failed and needed to be replaced. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ELECTRICAL SYSTEM,ENGINE | Engine Light came on, performance rough at various speeds / conditions, and smelled like burning and strong urea smell. GM Maintenance identified a failed DEF injector / replaced | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER,ENGINE | No warning; picking up child from daycare. went to depart daycare when my dash lit up like a Christmas tree with various errors, alerts, warnings; along with, not being able to start. had to be picked up by spouse and get the truck towed to the dealership for maintenance. Maintenance tech discovered that the grounding straps for the truck needed to be replaced / resulting in a complete electrical failure of the vehicle. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | Vehicle was going in for warranty recall; however, i requested they look at the DEF system as my DEF gauge would bounce between full and empty; along with, alert me of going into LIMP mode. GM Maintenance updated the recall and noticed that the DEF tank sensor failed and required to be replaced. | Crash: No Fire: No | Unknown |
| May 2025 | ELECTRICAL SYSTEM | After repair got a few miles down the road and noticed the volt meter jumping back and forth between the white lines. Line would slowly go up to max line and then slowly drop back down to lower limit and continue to go back and forth. This was very concerning to myself and i was waiting for something to fail while driving. Got about 10 miles away and was to concerned / returned the vehicle Informed by GM Maintenance tech that this is what / how the vehicle is designed and that it is the operating within its parameters. I expressed that only time i noticed something like this was prior to an engine light / electrical failure; however, maintenance team expressed GMs stance that it is operating within tolerance. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | Vehicle drop in gear / down shift while driving on the highway. went from 75MPH down to 55MPH due to high RPM revs. | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER | Rear window is leaking top coners from seal or plastic creating black mold inside of truck | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked while accelerating and while coming to a stop. The check engine warning light was illuminated. The vehicle was taken to the dealer, but no cause of failure was found. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 65,000. | Crash: No Fire: No | 65,000 |
| May 2025 | ENGINE | Engine started rough idle, reduced power, poor acceleration, ticking and knocking noises, and a check engine light and a few other lights came on the dash. Safety was not a risk at time of incident. Problem has NOT been diagnosed yet BUT have done a ton of research and it’s all leading towards lifter failure/misfire issues. No warning lights or symptoms prior to sudden problems. | Crash: No Fire: No | Unknown |