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 |
|---|---|---|---|---|
| May 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while attempting to start the vehicle, the vehicle vibrated abnormally. The engine warning light was illuminated. The contact stated that on another occasion, while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine. There was no warning light illuminated. The vehicle was towed to the dealer; however, a cause for the failure was not found. The vehicle was not repaired. The failure recurred and the contact stopped driving the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 110,000. | Crash: No Fire: No Towed | 110,000 |
| May 2025 | POWER TRAIN,ENGINE | This car had lifter motor failure at 135K miles and Transmission failure at 145k miles, the torque converter of this truck is the culprit of many issues as the lifter issues. | Crash: No Fire: No | Unknown |
| May 2025 | UNKNOWN OR OTHER | I purchased a 2020 GMC Denali Sierra 1500. My oil light has came on twice and I have taken it into the dealer and dealer has said that that's normal. That car loses oil. I'm retired so I do not utilize the vehicle every day I think since I've had the vehicle I've put on several thousand miles very very low mileage put on. And I'm being told that I need to check the oil basically before I take the vehicle anywhere. During the first time when I bought the vehicle in when the light came on the mechanic said in the paperwork from GMC service that my engine oil was extremely low. This last time that I did take it in, I have some type of mechanical background, so I pulled the dipstick out and it was halfway full with oil. I took a picture of that dated the picture and said I took it in before service while when I took it into the service department of course when I came home, they said that everything's fine and so on and so on and that didn't sit well with me. So I went ahead and let the car settle. Let the car cool down several hours later. I went ahead and checked the dipstick and the dipstick was full. They went ahead and put oil into my vehicle and told me that everything's fine. And I have noticed that there are lawsuits out in regards to oil consumption issues on these vehicles. When somebody spends the amount of money they spend for these vehicles we should not have to be checking the oil almost every time we drive it. I've had multiple vehicles on 50 years old and I've never had to check the Oil like it was 1914 before you go on a trip or even drive your vehicle. I am not trying to blame the Dealership only being told that everything's fine but GMC the company needs to rectify this problem because there is going to be a time that people are going to forget about the oil and burn up an engine and then you're putting them out thousands of thousands of dollars because of a mistake GMC made they're trying to cover it up as you see with the current recall in regards t | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission unexpectedly downshifted. There was no warning light illuminated. The vehicle was able to restart. The vehicle was taken to the dealer, where it was diagnosed and determined that the transmission had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 70,000. | Crash: No Fire: No | 70,000 |
| May 2025 | ELECTRICAL SYSTEM,SERVICE BRAKES | I was driving about 45 mph when the vehicle started to brake on its own. Message center said "Brake Failure max speed 62 mph". I had to move the vehicle, so I continued forward. It was still trying to self-brake, i decided to stop and turn ignition off so computers could re-set but I had no brakes. I had to stand on brake pedal to get it stopped. Turned ignition off and restarted. The problem was gone, but it happened again 2 weeks later. Took to dealership where purchased and they said it needed a computed recalibration. Something I didn't know about. They charged me $200 to recalibrate the computer. My issue is the danger of not having brakes, not the $200. How many similar vehicles could this happen to? | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE AND ENGINE COOLING,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 5 MPH, the vehicle made an abnormal popping sound. The check engine and the ABS warning lights were illuminated. The messages "Parking Brake Service" and "ESC Service" were displayed. Additionally, the contact stated the vehicle experienced a reduced fuel range. The vehicle was taken to the dealer, where it was diagnosed that the lifters had fractured, causing damages to the engine. The dealer determined that the engine needed to be replaced, and the part was ordered. The vehicle was not repaired. The contact related the failure to NHTSA Action Number: PE25001 (Engine, Engine and Engine Cooling). The manufacturer was notified of the failure. The failure mileage was approximately 80,100. | Crash: No Fire: No | 80,100 |
| May 2025 | ENGINE | Motor failed with no warning, motor was replaced at a GM dealer for $12,000. Mechanic stated he believed it was a main bearing failure. Not under warranty. | Crash: No Fire: No | Unknown |
| May 2025 | STEERING,SUSPENSION | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle started pulling to the left, and the vehicle ended up in the next lane. 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 was unable to duplicate the failure. The vehicle was not repaired. The contact stated that the vehicle had been taken to the dealer six times because of the failure. 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 17,000. | Crash: No Fire: No | 17,000 |
| May 2025 | ENGINE | On [XXX] at around noon I was driving my 2020 GMC Sierra northbound on [XXX] 26 miles north of Moab Utah. My truck died and I attempted to coast to the next passing lane but did not make it. The shoulder was about 3 feet wide and then had a steep drop off. I pulled over as far as I could but the majority of my truck and trailer was still in the only northbound lane. The northbound traffic was forced to cross over the double yellow into the oncoming southbound traffic. The concern was getting rear-ended by northbound traffic behind me or a head-on collision with the northbound traffic veering into southbound traffic. I made several attempts to restart the truck and the dash just goes blank with no attempt from the starter. We waited for a tow-truck and about an hour into this wait Utah Highway Patrol arrived and parked behind us with his lights on warning traffic from both directions. There were no precursors to this failure or notifications. I didn’t even hear any noises. There was no physical damage or any leaking fluids. It just quietly stopped. John Elway Chevrolet informed me the bearings failed and the engine seized. I wanted to keep the core for evidence due to learning about the numerous catastrophic failures of the L87 engine I had. Keeping the seized core was going to cost me double the cost of a rebuilt one ($7000). When I asked the service Manager, Ben why its twice the cost? He said, “GM doesn't want you keeping the core and they can set whatever price they want .” I have had this truck since it was new (6 miles) and noticed unusual oil consumption early on. I would never make it to the next oil change without having to add oil, even with the very first oil change. I inquired about this with the dealer and told this extreme oil consumption was normal and given Bulletin 01-06-01-011M. I did not involve my insurance because they do not cover engine failure. I paid $12,653.97 for a remanufactured long block. Of that was $2469.93 was for parts not need INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| May 2025 | SEAT BELTS,ENGINE | Our middle seat belt has stopped working in the back seat- we have not had it replaced yet. No damage was done on it by us, but will not click into the buckle. Driving on the hi-way engine started making awful noises. We pulled over and had the truck towed to Royal Moore GMC in Hillsboro Oregon as we didn't want to cause any more harm to the engine. Royal Moore GMC informed us the engine rod bearing failed on [XXX], leading to breaching of the engine block by the rod. This caused us to replace the entire engine at the cost of over 13,000$ and no vehicle for over 3 months. (Along with engine replaced they told us we had to replace the O2 sensor as the light came on after the engine was replaced). We had to take a hardship loan to get the engine replaced, and had the truck back for 1 day before we had a o2 error l light came back on. At this time (May 5th) we are still waiting for our truck back. Royal Moore doesn't know why the engine light is on- and contacted TAC for GMC. We also contacted GMC multiple times when we were waiting for the engine. They have offered no help to us besides empty promises to call us back later. 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 | Check engine and ECM errors. The dealer replaced one bank lifter. Shortly after, a similar issue was caused by reassembly. Approximate mileage: 30 K. A month later, the same issue, but this time the vehicle was not drivable, with very low engine power. The dealer stated lifter failure and camshaft damage, engine replaced January 2024, mileage 31 K. Currently 42K and had one instance of ECM error, which only lasted a few seconds, but the engine faltered and lost power. At the most recent oil change, the dealer said no error codes were present. GM indicated that my VIN is not covered under the most current recall. Since the engine was replaced in 2024, there is virtually no possibility that the engine replacement was not a new engine and should fall under this most current recall. | Crash: No Fire: No | Unknown |
| 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 | 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 | 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 | 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 | 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 | 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 | Engine locked up | Crash: No Fire: No | Unknown |
| Apr 2025 | ENGINE | Shut off in traffic twice | 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 | 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 |