Complaint volume
425 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
425 consumer-submitted complaints on record for the 2020 GMC Sierra, grouped by component category.
425 Total complaints
11 Crash reports
4 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, 4 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 118 complaints, with an average reported failure mileage of 44,233 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
4 Fire
6 Injury
0 Fatality
28 Towed
4 Medical attention
What are the most common 2020 GMC Sierra complaint categories?
ENGINE 125
POWER TRAIN 36
ELECTRICAL SYSTEM 21
POWER TRAIN,ENGINE 17
SERVICE BRAKES 16
STEERING 14
UNKNOWN OR OTHER 14
ENGINE AND ENGINE COOLING 9
SUSPENSION 9
ELECTRICAL SYSTEM,ENGINE 8
425 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Jun 2025 | ELECTRICAL SYSTEM | Power Steering works sometimes and then stops Trailer Break system issues | Crash: No Fire: No | Unknown |
| Jun 2025 | ELECTRICAL SYSTEM,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving on a main road at 40 MPH, the vehicle lost automotive power, causing the vehicle to shut off. There was no warning light illuminated. The vehicle was towed to a local dealer where the vehicle was diagnosed, and the contact was informed that the engine wiring harness was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 80,000. | Crash: No Fire: No Towed | 80,000 |
| Jun 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment before the vehicle lost motive power with the check engine warning light illuminated. The vehicle was towed to the residence. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The dealer referred the contact to the manufacturer for further assistance. The manufacturer was made aware of the failure. The approximate failure mileage was 138,000. | Crash: No Fire: No Towed | 138,000 |
| Jun 2025 | VISIBILITY/WIPER | The rear back glass is leaking water excessively in to the inside of the vehicle when it rains or gets washed. The vehicle is available at any time for inspection. The amount of condensation that accumulates on all the interior windows makes it impossible to see out of the vehicle. The defrost can not handle the amount of moisture build up. The Dealer knows about this condition and it has been verified by a window company. The manufacture knows and understands there is a problem and has put out a Technical Service Bulletin ( TSB 18‑NA‑383 ) for this issue but will not cover the repairs. GM knows that every single vehicle with this window designs from 2019-20121 will leak just outside the 3 year 36k mile warranty coverage. The cost of repair is approximately $2k. Dealer will not cover repair. | Crash: No Fire: No | Unknown |
| Jun 2025 | STEERING | While driving vehicle at normal speeds the steering assist goes out and becomes very hazardous to drive. It is intermittent and does not do it all the time. When connected to dealer diagnostic machine it throws several codes. I have read on several GM sites this problem is widespread and GM is actively saying they haven’t heard of this problem. When the problem occurs it is almost impossible to control the truck to get over to the side of the road. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | I own a 2020 GMC Sierra 1500 with a 5.3 liter engine..... My engine lifters failed at 105,235 miles.... Lifter broke and damaged the Cam Shaft to a point that required full engine replacement costing me $10,800. When I asked GM for help, they denied because I went to a local repair shop with certified mechanics. I believe GM is fully aware of this problem and they are ignoring I think GM should pay for at least half of my repair bill. Thank you! | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | Engine failure/ lifter issue with no prior warning. Driving down the road vehicle suddenly lost power and error message appeared. The vehicle was inspected by GM dealer and extended warranty company in late 2023. We no longer own this vehicle | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | My engine slowed down on the interstate. My steering wheel was visibly shaking and I lost the steering access control. The truck threw an Cylinder 6 error code. At the mechanic, they identified that at least one of my camshaft lifters had failed. If I had continued to drive my vehicle, the engine block would have eventually locked up. | Crash: No Fire: No | Unknown |
| Jun 2025 | SERVICE BRAKES | I was driving my 2020 GMC Sierra 1500 on a local street when the dashboard suddenly displayed a “Brake Failure” warning. I immediately realized I had no braking power and had to safely roll into an uphill parking space to stop the vehicle. While waiting for the tow truck, I researched the issue and discovered there is a known recall related to the brake calipers on some 2020 Sierra 1500 models. However, when I entered my VIN, it showed no open recalls. I also contacted GMC directly, and they confirmed that there are no active recalls associated with my vehicle. Additionally, the vehicle's onboard information system indicated that the front brakes were at 65% and the rear brakes at 80%, suggesting that brake wear was not a contributing factor. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | I took my 2020 GMC Sierra 1500 to the dealership after Cylinder #5 seized while driving, and I was forced to replace the entire engine. At the time, I contacted the dealer and was told there was no recall related to this issue. However, I have since learned that GMC has issued a recall for similar engine problems affecting 2021–present Sierra 1500 models, but not for my 2020 model year. I believe this issue may be related and would like further investigation and consideration. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | Vehicle currently has 104K and needs a 3rd engine. The same issue happened to the second engine as the first. While Driving the engine just stop working. They say it is a problem with the camshaft. Metal gets into the transmission and that also has to be replaced. A vehicle engine should not just stop working! Especially on an interstate. GMC refuses to add this engine to the recall list. However, I don't understand how the safety of families can continue to be placed in jeopardy. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment and the vehicle then failed to exceed 30 MPH. No warning lights were illuminated. The vehicle was taken to the dealer, who were unable to determine the cause of the failure. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); but the VIN was not included. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was 90,000. | Crash: No Fire: No | 90,000 |
| Jun 2025 | ENGINE,FUEL/PROPULSION SYSTEM | Transmission has slipped and shuddered multiple times. We have had it diagnosed at gmc dealership and our mechanic, advising that it is 8L90 transmission failure. It will slip to lower gear abruptly, causing for possible safety issues especially on the highways. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | 1. On 05/9/25, the exhaust emissions system malfunctioned, triggering diagnostic trouble code P2C7A (exhaust emissions system failure). This repair, the seventh attempt since June 2024, addressed the same recurring emissions issue previously involving replacements of components such as the NOx converter (02/18/25, 03/13/24) and EGR valve (02/18/25). The vehicle is available for inspection upon request. 2. The P2C7A failure risks limp mode, reducing vehicle power unexpectedly, which is hazardous on highways, especially while towing. Exhaust emissions system malfunctions release excessive pollutants, posing environmental and health risks to others. 3. Yes, the P2C7A code was confirmed by dealer during the 05/9/25 repair, following prior confirmations (e.g., 03/31/25–04/05/25. 4. The vehicle was inspected by Young Chevrolet-Cadillac during multiple repairs (e.g., 03/31/25, 05/9/25). 5. Yes, the check engine light and OnStar emissions alerts appeared prior to the 05/9/25 repair, first noted ~June 2024 (P2C7A onset). Exhaust smell and reduced fuel economy were observed intermittently. Symptoms persisted post-03/31/25 repair, leading to the 05/23/25 service. | 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 | 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 | 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 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 |