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 |
|---|---|---|---|---|
| May 2025 | ENGINE | I was driving on the frontage road that enters the freeway when then engine suddenly failed and stalled. It lost power and seemed like it was misfiring. All the warning lights on the dashboard came on as this happened but there were no warnings lights, messages, or symptoms before this happened. The sudden loss of power posed a risk to my safety because it could have caused a crash or left me stranded. I had my vehicle towed to the Freeway Chevrolet dealer in Chandler, AZ where they inspected the vehicle and confirmed the engine had a camshaft and lifter failure. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | Engine Lifters failure. Problems with Dynamic Fuel Management System | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,ELECTRICAL SYSTEM,UNKNOWN OR OTHER | I have taken my vehicle to 3 seperate mechanics (GMC, AAMCO and Independent). They all agree that my valve body inside the transmission must be replaced. The problem is that valve bodies are on a national back order and cannot be fullfilled for months, putting my transmission at risk for further failure. Reading online forums, there are many GMC owners facing this same issue. The mechanics at GMC are requesting that I change out my entire transmission, since that will be a quicker solution than waiting months for that valve body. Now, I am being told that they are having difficulty locating an original manufactured transmission. This puts me in a serious bind because my truck is my only vehicle and there are no valve bodies or transmissions to fix this issue. My truck is only a 2020 and I just surpassed 100k miles. There were no dashboard warning lights that indicated my trucks problem. Only the fact that my truck is shuddering when shifting gears and that a diagnostic tool had to find the source of the problem. This problem started about 5 months ago and has progressivly gotten worse. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated that occasionally while driving at various speeds, several unknown warning lights remained illuminated, and the vehicle lost motive power. The vehicle was taken to a local dealer to be diagnosed, and the contact was informed that DTC: P0016 was retrieved, and it was confirmed that the engine had failed and needed to be replaced. The vehicle was not repaired. The contact referenced NHTSA Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING). The contact expressed a concern that the remedy was the same engine that was prone to failure. The manufacturer was notified of the failure. The approximate failure mileage was 150,000. | Crash: No Fire: No | 150,000 |
| May 2025 | ENGINE | 1) Complete Engine Failure. Vehicle is no longer is in possession for inspection but pictures and video can be provided. 2) My Truck stalled at 70 MPH going down the interstate. I was lucky to be driving in the right lane to glide to a complete stop. This could have been way worse, not just for myself but for others. 3) Shortly after the loss of propulsion on the interstate. The engine started knocking very loud and I brought it into Boucher GMC of Brookfield. After about a week, the conclusion was I needed a new Engine. The Bearings, camshaft, rods and other components within the engine were damaged. The dealership said it was because of Bad Oil. 4) Parts were inspected and Dealership provided pictures. Not sure what they did with the junk parts. 5) I initially brought in the vehicle where it was purchased at Kunes of Stoughton WI for a Check engine light that read a P06DD error code at 56472 miles on the truck. They performed a software update and sent me on way. Since then, I was dealing with a on and off engine light which eventually brought me to a engine replacement at about 70,000 miles. None of this was covered under warranty and I had to pay for all of this out of pocket. In the events of all this. GMC had my truck for about 3 months. I had to purchase another vehicle because it was cheaper then renting one, GMC didn't have a loaner I could use. I could not perform my everyday work tasks besides getting to and from work, because I did not have a truck to carry my everyday work tools. Now understanding the full impact of this faulty engine and that I could have done harm to others or my self, has me worried about driving a GM vehicle. After I received the new engine, approximately 2000 miles later, The new engine, not rebuilt started making a knocking noise, only to find out, it was the same issue after bringing it to the dealership. No engine lights or nothing. People should be scared to drive a vehicle with the L87 engine from GM. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Shut off in traffic twice | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Engine locked up | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | 3.0 LM2 Duramax engine failed at 91,000 miles. It needs a new engine and they are available with a 2-3 week wait time. The engine failure has been inspected and confirmed by the dealer. No symptoms or check engine lights were on prior to the failure. Problem first appeared 03/2025. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | I have had two engine failures within 2 years of buying a new GMC truck. The first occurred at 24,181 miles whereas i found engine failures is an all to common occurrence with these 5.3 liter engines, failures are wide spread, tons of complaints can be found with a simple internet or youtube search. The second engine failure occurred at 45,517 miles, again with lifer falling apart. Several service bulletins have been issues including reworking vehicles on dealers lots to replace faulty components but in my case i had over 16000 miles so they put the same parts in again and did not touch the other side which then failed two years later at in my case both were attributed collapsed lifter. This is a safety concern, there is no indication this is about to occur. The vehicle loses power, shakes, instrument panel lights up with various different warning lights. If you are passing another vehicle and this occurs it can be frightening as you have no idea what is happening and why you are no longer accelerating if you are passing some vehicles. The value of these vehicles is now also diminished, who wants a GM vehicle with two engine failures with 45k miles? No one, because it more than likely going to keep occurring until the engine is damaged beyond repair. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the low oil warning light illuminated even though an oil change had been performed within 1,000 miles. The vehicle was taken to the dealer, who diagnosed a failure with the piston O-rings, resulting in damages to the engine. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Action Number: PE25001 (Engine and Engine Cooling). The manufacturer was notified of the failure but provided no assistance. The failure mileage was 79,000. | Crash: No Fire: No | 79,000 |
| Apr 2025 | POWER TRAIN | The transmission is jerking and sometimes it will not shift enough to get out of others ways. Severe slippage in the transmission I have taken the truck to the shop 3 times for the same issue. Now they tell me I need a new transmission. | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while attempting to start the vehicle, the vehicle failed to start. There was no warning light illuminated. The contact pushed the vehicle out of the garage. The vehicle was towed to a dealer where it was diagnosed that the spun bearing had failed. The contact was advised that the engine needed to be replaced. The engine was replaced. The contact stated that recently there was an abnormal sound coming from the engine. The vehicle was not diagnosed or repaired after the most recent failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 40,000. | Crash: No Fire: No Towed | 40,000 |
| 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 | SERVICE BRAKES | Brake monitor repair keeps illuminating since 2/1/2025! Replaced all brakes and rotors, yesterday 4/27/2025. now don't drive over 43 mph illuminates, emergency brake illuminates says push brake peddle to disengage parking brake yet parking brake has never been engaged | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN,ENGINE | Merging onto highway, lost engine power. Cylinder lifter failed, damaged cam shaft, caused damage to coolant system via metal debris, and engine needs to be replaced. 76,000 miles on vehicle, regularly serviced at dealership. I inspected the parts, and was shown the cylinder lifter that had failed and fragmented as well as the galled cam shaft. There were no prior indications of impending failure (no hard shifts, jumping, warning lights, etc). Warning lamps turned on after failure. I asked the mechanic at the GMC Dealership what caused the failure, and wasn't given a definitive answer. | Crash: No Fire: No | Unknown |
| 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 | 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 | 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 |