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 |
|---|---|---|---|---|
| Apr 2025 | POWER TRAIN,ENGINE | 1. Vehicle automatic transmission failed during routine highway driving. Significant drivetrain vibration and limited gear availability. Warning lights included: ESC. - Electronic Stability Control TSC - Traction System Control Emergency Brake Fault light Power Steering assist reduced Flashing Yellow Engine Warning light. 2. White exhaust smoke upon arrival at GMC dealership. GMC technician advised full diagnostic would be required to assess extent of transmission failure and cause of white exhaust smoke. Service technician subsequently communicated that the engine was “failed” and would have to be replaced. Vehicle could not be driven and so full extent of transmission failure could not be assessed UNTIL ENGINE IS REPLACED!?! | Crash: No Fire: No | Unknown |
| Apr 2025 | ELECTRONIC STABILITY CONTROL (ESC),ELECTRICAL SYSTEM | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 40 MPH, the vehicle failed to properly respond. There were no warning lights illuminated; however, the message ESC was displayed. The contact stated that the brakes, steering, and a message to check the trailer brakes was also displayed. The contact pulled over to the side of the road and the brake pedal was depressed several times however, the brakes failed to respond, and the vehicle was difficult to control. The vehicle was towed by AAA and then towed to a dealer however, the vehicle was not yet diagnosed. The contact stated that the brakes were inoperable, and the control center was destabilized. The vehicle was not yet repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline. The failure mileage was approximately 125,000. | Crash: No Fire: No Towed | 125,000 |
| Apr 2025 | ELECTRICAL SYSTEM,ENGINE,FUEL/PROPULSION SYSTEM | I was about 45 miles or so from home on [XXX]. As I left a business my truck went about 100 feet and the engine stopped working . No warning. Truck was towed to a GM dealer in Wilmington Il. It was determined the cause was due to the wiring from the engine ECM that was run over the top of a very sharp plastic mounting bracket for the ECM. The wire had been cut because of the way this was done at the factory. In addition the fuel pump also needed to be replaced . At the time of this, the truck had 39,140 miles on it. I had no warning this was about to happen. No check engine light went on , etc. Most of my route home is on the highway . Had this not happened on a side street , I would have been involved in an accident. I ended up paying $865.42 plus towing for this repair I should not be paying for. The people at the GM dealer told me this has been happening on numerous GM pick up trucks. This is NOT a maintenance issue or an isolated case. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Apr 2025 | STRUCTURE | Had water leaking into cab of truck. First incident they stated it was a rear window seal and it was "repaired" under warranty. Second incident I was advised it was body panel separation where the cab roof and side body seam was leaking. It was repaired by sealing with "body seam sealer." I later read these repairs should have been welded. This was after the warranty expired and I had to pay for it. I then read on the Silverado/Sierra forum this repair should have been a weld not just "glued" is this a safety issue? | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | 2020 GMC Sierra "Denali" 6.2L engine with only 64,000 all original well maintained at miles -- NO prior issues no unusual sounds or indications of any issues. Vehicle has had timely maintenance regularly. engine lost power and began shuddering severely. Immediately taken to GM certified dealership upon which charged almost $1600.00 for engine analysis. Diagnosis is cylinder # 5 had lifter collapse which in turn ruined the camshaft. Will have to wait 4 weeks for parts and since GM power train warranty (conveniently) only covers first 60,000 miles the total engine rebuild is out of my pocket. Total price $9,741.11. THIS IS RIDICULOUS AND GM NEEDS TO REPAIR OR REIMBURSE EVERY SINGLE OWNER THAT EXPERIENCES THIS ISSUE IN FULL. I think GM knew about this issues and hopes it will go away but this really pisses me and SHOULD everyone else too. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Second engine failure in 8 months. 1st with 97k miles and last after 15k on a brand new 6.2L engine. | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 65 MPH, the vehicle briefly started to shimmy. Upon decelerating, the vehicle returned to normal functionality, but the failure became a regular occurrence. No warning lights were illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the transmission. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train), 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 unknown. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE,FUEL/PROPULSION SYSTEM | Number 5 cylinder failure. Engined has failed cylinder is scored causing the engine to miss and lock up. The engine which is a 6.2 l87 is now under investigation for a piston failure causing the engine to lockup. The piston and engine issue has been investigated by my local repair shop and I can provide written and bore scope pictures of the failure. Yes the engine light was on the ESC was disabled and needed replaced and the traction control was disabled also the emergency brake was enabled and then failed | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 70 MPH, the check engine warning light illuminated, and the vehicle lost motive power. The contact attempted to restart the vehicle however, the vehicle failed to restart. The contact stated that several nearby drivers assisted with pushing the vehicle off the roadway. The contact stated that the first failure occurred the day after the vehicle was purchased. In addition, the contact stated that the failure had also occurred three times within one week. The vehicle was towed to the dealer where the vehicle was purchased. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was made aware of the failure, and a case was filed. The failure mileage was approximately 123,000. | Crash: No Fire: No Towed | 123,000 |
| Apr 2025 | SERVICE BRAKES,FUEL/PROPULSION SYSTEM,FORWARD COLLISION AVOIDANCE | recently when starting truck brake message alert comes across on dash reading brake error, and not to drive above 45 miles per hour and brakes are NOT totally operational, meaning brake pedal has alot of play in it to bring truck to a stop. Have to turn off vehicle , sometimes repeatedly before it apparently resets computer system. This has now occurred four times in last five months. Events and dash warning message very similar to recall issued 3/3/20, but listed as "complete" on recall data base. Need to seriously and immediately looked into and corrected! | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN,ELECTRICAL SYSTEM,SERVICE BRAKES | Dear NHTSA, I am filing a complaint against General Motors, LLC (GM) for failing to follow through on a legally binding lemon law settlement and leaving me with an inoperable, unsafe vehicle. Vehicle Information: •Vehicle: 2020 GMC Sierra 1500 •VIN: [XXX] •Date of Purchase: [XXX] •Dealership: Diamond Chevrolet Buick GMC Nature of the Complaint: 1.Vehicle Declared a Lemon: •GM acknowledged that my vehicle was defective and offered a CCP § 998 settlement on April 18, 2024, for $97,000 plus pre-judgment interest. •Despite accepting the offer, GM has failed to facilitate the buyback or repurchase of the vehicle. 2.Ongoing Safety Hazard: •The vehicle is non-operational and poses a safety hazard due to repeated transmission failures, loss of engine power, steering/braking issues, and limp mode activation. •GM’s delay in replacing the vehicle leaves me exposed to ongoing safety concerns. Request for Action: I request that the NHTSA: •Investigate GM’s failure to address and rectify the vehicle’s safety issues. •Document GM’s negligence in resolving safety defects under a recognized Lemon Law claim. •Initiate necessary action to protect consumers from ongoing safety hazards caused by GM’s failure to act. Please contact me for additional information or supporting documentation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE | At 59000 miles my lifters were rebuilt on the 6.2 liter engine because of a failure in the 1 and 3 piston. Gm paid for the repairs and then At 79000 miles the motor completely blew resulting in complete failure and seizing the motor and heavy metal chips were reportedly found in oil pan. Gm claimed it was a result of me not doing regular oil changes however I suffer from OCD and I am automotive engineer and my oil was changed early in most cases with my truck. Gm will not take responsibility and at the time they wanted $16k to fix my truck. I was going through a very tumultuous divorce and had to pay atty $34k for that wnd could not pay $16k for a new engine resulting in me having to give my truck back to bank and I have not been able to buy a truck or vehicle since then as it ruined my once perfect credit of 820. It’s changed my life forever and GM should take responsibility. I will never buy another GM product again and my father worked for them my whole life and my family only drove their products. | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 70 MPH, the low oil pressure warning light illuminated. The contact pulled over to the side of the road and noticed that the oil level was abnormally low. The contact added oil to the vehicle and continued driving. The vehicle was taken to Mike's Garage, where it was diagnosed that the valve cover was fractured; however, the part to repair the vehicle was on backorder. The contact related the failure to TSB Number: 22-NA-027. The dealer was notified of the failure and informed the contact that the vehicle was not covered under the TSB. The vehicle was not repaired. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 96,000. | Crash: No Fire: No | 96,000 |
| Mar 2025 | ENGINE | The Lifter failure, bent rod, and basically ruined the the cam shaft, the vehicle has had engine replaced and the current engine is now acting up. once again. | Crash: No Fire: No | Unknown |
| Mar 2025 | UNKNOWN OR OTHER | Shift to park message appears when in park and engine is turned off. Transmission control had an internal circuit failure. Park not fully engaged and vehicle could roll. Problem confirmed by dealership. Prior recalls for earlier gmc models but not my year. | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE | While driving our 2020 Sierra AT4 down the highway at 65 mph, the engine suddenly cut out and started sputtering. Every light came on. We pulled off the highway and had the truck towed. Our highly trusted, family mechanic company diagnosed lifter 5 was twisted and stuck, along with another stuck lifter. The cost to replace the engine was one hundred dollars more than repairing the two lifters. They purchased a new engine through Van Chevrolet and were surprised the cost had recently decreased from $7-8k to $3900, to purchase a rebuilt engine. The engine appeared to be new, with the bolt threads unused. The new engine comes with a 3year 100k mile warranty through the dealership. We called GM, they said since we went to another mechanic they would not speak with us. | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE | The engine, while driving down the road, incurred a failure to the pusher rod in the #5 cylinder. This occurred at 6750 total miles on engine. Engine failure was repaired by a dealership. The failure occurred again at 99,500 miles to the same #5 cylinder causing major engine damage leading to the replacement of the engine. Our safety was put at risk as the truck decelerated and began vibrating. The second failure occurred and the engine shutdown. These incidents occurred without warning, Yes, a dealer was involved in both incidents. Only a dealership has been involved. The warning occurred after the failure. | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN,SERVICE BRAKES,ENGINE | -Transmission valve body Failure, Wheel lock up, ABS Event, Loud Bang and a Flashing "D" on Driver Information Center (DIC) when Lightly or Moderately Accelerating Forcing an 8-7 or 8-6 Downshift -When all four tires lock up at a high rate of speed, this puts the driver, the passengers, and all others on the road at risk for injury or death. -Yes, the problem has been found in a document by my local dealer that this issue was added to my exact vehicle's service manual on 11/27/24. The document describes in detail the exact scenario I have been involved in multiple times. It is deemed as #21-NA-275. It locks up the tires randomly to the vehicle in mid acceleration at any speed including 80 miles per hour in one instance for me. -Yes, the dealership inspected it and found the issue to correlate with the newly added section to the service manual, 13333166. This document ID is 5925530 and the added information to the dealership is #21-NA-275. The GMC manufacturer has been contacted as of 3PM MST 3/14/25. Insurance doesn't deal with mechanical problems. The police will only be involved when there is death or injury. -No. The only warning that happens is simultaneously as the vehicle locks up the tires causing the driver (me) to inevitably try to save myself and others, swerving and trying to focus on not hurting myself or others but I did notice the "D" flash on one of these occasions. This is the most dangerous issue with a vehicle I have ever even considered. At any time, for any reason, all four tires can lock up at any rate of speed and cause multiple casualties. The way to fix this is to spend $3,000 which I am sure many people like myself do not have. This means there are thousands of these exact make and models of vehicles on the road right now. Please do not take this lightly as I have almost crashed multiple times with people in my vehicle due to no fault of my own. | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN | The contact owns a 2020 GMC Sierra 1500. The contact stated while accelerating from a complete stop, the vehicle lunged forward. The contact stated that the failure recurred while driving at various speeds depressing the accelerator pedal, and while decelerating to come to a complete stop. The check engine warning light was illuminated. Additionally, the contact stated that while coming to a complete stop at a traffic light, the vehicle lunged forward violently, as if the vehicle had been rear-ended. The vehicle was taken to Quality Plus Automotive, where it was diagnosed that the transmission had failed and needed to be replaced. The local dealer, Leith GMC (919) 366-1000), and other dealers were contacted and informed the contact that an estimate for the repair could not be provided because the transmission part was not available. The vehicle was repaired by Quality Plus Automotive. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 75,450. | Crash: No Fire: No | 75,450 |
| Mar 2025 | POWER TRAIN,UNKNOWN OR OTHER | The Transmission cooler lines broke and spilled out all the oil/fluid on my 2020 GMC Sierra Elevation pick-up truck. Once all the fluid was spilled out the Sierra truck would no longer move. The Sierra truck was towed to the dealership I originally purchased the vehicle. The dealership was Cranbury Buick GMC. The dealership mentioned that the hoses broke/leaked from the crimped housing at the ends of the hoses. The dealership stated that the original OEM transmission cooler line hoses were discontinued and new OEM replacement transmission cooler line hoses were created. Please see the attached dealership bill/invoice for the parts and labor to fix the cooler line issue. I feel this issue should be a recall on all 2020 GMC Sierra trucks, especially if GM replaced the original OEM hoses with newly created OEM hoses Thanks [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN,SERVICE BRAKES | Vehicle shifting poorly, and I have had a bunch of brake and rotor issues. | Crash: No Fire: No | Unknown |
| Mar 2025 | PARKING BRAKE,STRUCTURE,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the parking brake independently activated. In addition, the contact stated that the vehicle had an oil leak from the oil pan. The contact stated that the oil needed to be added every two days. The contact stated that the alert system warning light was illuminated. The vehicle was taken to the dealer; however, the failure was not duplicated. The contact was informed that the failure could not be duplicated, because no active codes were retrieved. In addition, the contact stated that the frame had corrosion. The vehicle was taken to the dealer for the corrosion failure, however the contact stated that the previous dealer had failed to help. The dealer confirmed the corrosion; however, the vehicle was not repaired. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 10,000. | Crash: No Fire: No | 10,000 |
| Mar 2025 | ELECTRICAL SYSTEM | Had GMC (Leominster, MA), perform the safety recall for the transmission on my Sierra. This is the one for the rear wheel lockup that requires a software update. My battery was completely dead after the vehicle sat for a week. No accessori s plugged in, and it's a 6 month old battery Battery tested fine and is charging now, but it appears the CPU never fully powered down after the software update, resulting in needing multiple jump starts and 3+ hours of run time to charge the battery enough to turn over on its own. I can see this being a safety issue in relation to the Auto-start, because when it is being used, the battery is needed to restart the engine. This could result in a stall at an intersection, and if drivers are not alert, may collide with a stalled vehicle. | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN,ENGINE | Lifters failed and cam shaft was busted. Standard issues with 6.2L engines. Was traveling down highway and vehicles was shaking violently. Inspection report available. Has been inspected by GM service center. No symptoms or warnings prior to failure. | Crash: No Fire: No | Unknown |
| Feb 2025 | ELECTRICAL SYSTEM | While driving on interstate transmission would “lock up” momentarily creating drastic drop in speed and unable to shift gears and accelerate. “D” would start flashing in dash board. Dealership said this is unrelated to current recall about rear wheels locking up from valve body failure and instead this is an electrical issue. Dealership also stated this is the 2nd truck in a week they have had come in with this issue. Almost caused accident on interstate with my family and I as a result of sudden drop in speed and unable to accelerate with multiple cars behind us. | Crash: No Fire: No | Unknown |