Complaint volume
424 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
424 consumer-submitted complaints on record for the 2020 GMC Sierra, grouped by component category.
424 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
424 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Jan 2026 | ENGINE | Bought the truck less than four months ago and as of yesterday it consumed a substantial quantity of oil and later refill. However today it made a noticeable noise until it shut off permanently. Dealer did not disclose this | Crash: No Fire: No | Unknown |
| Dec 2025 | ENGINE,FUEL/PROPULSION SYSTEM | I started to notice changes in performance around 75k miles. Seemed like performance was subpar compared to what was the norm. Seemed to lose some power. Minimal at first, more so just recently around 90k. Oil consumption was starting to accelerate at each oil change at 75k, 80k, 85k, 90k. To the point around 85k and 90k that I would not go over even 1 mile from the 5k threshold without changing the oil. Around 90k I could tell it was not getting any better, deficiencies were accelerating it seemed. At 91k miles I started to hear clicking noises and loss of power, starts were getting rough, bouncing at idle. I stopped driving it, only driving it to the dealership where I brought for a look at it. Will be driving it again for them to do a deeper diagnostic. Many misfires at cylinder 5. PO305 the issue. Showed up around 91k miles on 12/17/25 Now investigation into my model. I see online. | Crash: No Fire: No | Unknown |
| Dec 2025 | ENGINE AND ENGINE COOLING,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 35 MPH, the vehicle lost automotive power with the check engine warning light illuminated and the message "Vehicle Might Lose Power" displayed. The vehicle remained at the residence, and the contact used a self-diagnostic tool to retrieve a fault code related to the coolant valve D. The contact determined that the coolant valve D needed to be replaced. The vehicle was taken to an independent mechanic; however, the contact was unaware of the part that needed to be fixed in the vehicle. The vehicle was repaired. The contact researched and was made aware of an unknown NHTSA Campaign Number; however, the VIN was not under recall. The manufacturer was contacted and confirmed that the VIN was not under recall. The failure mileage was approximately 31,000. | Crash: No Fire: No | 31,000 |
| Dec 2025 | ENGINE,FUEL/PROPULSION SYSTEM | Fuel management system caused a lifter to fail (stuck) which resulted in camshaft damage at 77,611 miles. GM refused to cover the repair, although there is a pending class action lawsuit against GM for this very issue. Truck was repaired at a GM dealership - Sunrise Collierville, TN. Repair costs was approximately $7,000. This occurred during a 2.5 hour road trip which put lives at risk. The truck began to vibrate, and the check engine light came on. There was no other warning before the failure occurred. No police or insurance were involved. This occurred on 9/27/25. It took the dealership 32 days to diagnose and repair the issue. Thanks. | Crash: No Fire: No | Unknown |
| Dec 2025 | POWER TRAIN | While driving on the interstate at 70 mph, the transmission began to shudder. It continued the duration of the trip of 90 mins. Following day, the transmission is continuing to shudder and is now shifting hard. | Crash: No Fire: No | Unknown |
| Dec 2025 | ELECTRICAL SYSTEM,VISIBILITY/WIPER | The morning of December 12th, 2025 I used my vehicle to transport my daughter approximately 5 miles round trip from our home to drop her off at daycare and then I returned home. I used my front and rear defrost elements to expedite removal of heavy condensation which had formed on all windows overnight. This was approximately 7 AM. I parked my truck in the driveway and went inside until approximately 11:45 AM when I went to leave in my truck and noticed the rear sliding window had shattered. The window shattered and distributed tempered glass fragments all over the inside of the cab. Only approximately 10% of the window remained intact. I then reviewed the security camera footage from my driveway and discovered that the window failed entirely on its own with nothing hitting/striking/touching the window, nor any humans or animals in the vicinity. I attempted to take the vehicle to a GMC service department this morning (Dec 13) but due to their demand to keep the vehicle for 2-3 days to investigate yet unable to provide a loaner vehicle, I was unable to leave the vehicle in their possession and returned home. I plan to continue to contact GMC dealership service departments in hope I can find one which can provide a loaner vehicle, as I will need transportation to and from work in the coming days. I do have video footage of the incident although I am unable to add it below. | Crash: No Fire: No | Unknown |
| Dec 2025 | ELECTRICAL SYSTEM,ENGINE | The contact owned a 2020 GMC Sierra 1500. The contact stated that after the vehicle was purchased and while driving at an undisclosed speed, the check engine warning light illuminated. The dealer was contacted. However, the check engine light turned off, and the dealer refused to inspect the vehicle. The contact stated that while driving at an undisclosed speed, the vehicle jerked and the check engine light illuminated. The dealer was contacted. However, the warranty had expired, and the dealer refused to inspect the vehicle. The manufacturer was contacted, and the contact was offered a five-hundred-dollar coupon. The vehicle was taken back to the dealer. However, no cause for the failure was found. The contact stated that an unknown part was replaced. The contact stated that the failure persisted. The contact stated that while turning on the engine, the contact's sister informed him that smoke was emitting from under the hood. The contact turned off the engine, opened the hood, and noticed that all of the wires were melted. The contact splashed water on the wires. The contact checked underneath the vehicle and noticed that the plastic that was burnt was leaking residue. The vehicle was left at the residence where the contact's mother lives. The next day, the contact noticed that the front windshield had shattered due to the heat from the burnt wires. The insurance company was notified and referred the caller to take the vehicle to be inspected. The vehicle was towed to a collision center. The contact was informed that the vehicle had a factory defect. The vehicle was not repaired. The manufacturer was notified of the failure. However, no assistance was provided since the warranty had expired. The failure mileage was approximately 32,000. | Crash: No Fire: Yes Towed | 32,000 |
| Dec 2025 | ENGINE | In December of 2023 my 2020 GMC Sierra 1500 was driving down the freeway, experienced a jerking and low oil pressure. Pulled over and shut vehicle off and wouldn't turn back on, engine locked up. The vehicle received a brand new 6.2l replacement motor in April of 2024- $15k in parts and labor. This vehicle was not included in the recent recall, but obviously experienced a similar issue. This was at 75k miles. The car was owned by a different owner at the time of the engine failure. I bought the vehicle as a repo and proceeded to get the engine fixed on it. | Crash: No Fire: No | Unknown |
| Dec 2025 | ENGINE | Engine lost all power while driving highway speed. Vehicle towed to Cavender Chevrolet dealer in Boerne, TX. Dealer inspected and determined cam bearings damaged. Engine replaced with remanufactured engine. | Crash: No Fire: No | Unknown |
| Dec 2025 | POWER TRAIN,ENGINE | MY 2020 5.3 L GMC AT4 IS EXPERIENCING LOSS OF POWER WITH BUCKING & STALLING. CYLINDERS ARE NOT ACTIVATING WHEN CALLED CHECK ENGINE LIGHT IS FLASHING, IT STARTS ROUGH AND MAKES NUMEROUS NOISES AT VARIOUS SPEEDS, AS WELL AS AT IDLE. SO I BROUGHT MY VEHICLE TO MY LOCAL AUTO REPAIR SHOP. OUR MECHANIC FOUND TWO FAILED FUEL INJECTORS AND A FAILED THROTTLE BODY. THEN THE LOUD KNOCKS IN MY BLOCK FAILED AN ACOUSTIC TEST. HE ALSO DETERMINED THE LIFTERS, PUSH RODS AND CAMSHAFT ARE EXPERIENCING EXCESSIVE WEAR. THE AFM SYSTEM HAS FAILED! HE WARNED ME THAT FURTHER USE OF MY MOTOR (WITH ONLY 42K MILES ON IT) WILL CAUSE A CATASTROPHIC FAILURE. MY RESEARCH SHOWS THAT THESE ISSUES ARE BECOMING COMMON OF 5.3 GMC MOTORS. WE SEARCHED THE COUNTRY FOR A REBUILT MOTOR AND FOUND THAT NONE ARE AVAILABLE FOR THE NEXT SEVERAL MONTHS. HOWEVER, I WAS ABLE TO FIND A NEW MOTOR AT MUCH GREATER COST. GMC HAS DECLINED ASSISTANCE AT THIS TIME. MY VEHICLE HAS NO VALUE AS IS, SO I ORDERED THE NEW GM ENGINE. WITHOUT THE DOD SYSTEM, THESE ENGINES WERE DESIGNED TO GO WELL OVER 100,000 MILES. I AM A FAITHFUL GMC OWNER AND NONE OF MY PREVIOUS GMC TRUCKS (2003, 2013, 2015, 2019) HAD SUCH A MAJOR PROBLEM. NOW THE 2020'S FUEL SAVING SYSTEM HAS FAILED AND REQUIRES REPAIRS THAT AMOUNT TO HALF THE VALUE OF MY TRUCK. WHEN A FULL SIZE TRUCK STALLS ON THE HIGHWAY IT'S CERTAINLY LIFE THREATENING. | Crash: No Fire: No | Unknown |
| Dec 2025 | ENGINE | Driving on the Highway, the engine shuttered, but kept going. When I had to slow down, the engine stalled and would not restart. It left me in the center lane of a three lane highway. I was able to push the vehicle off to the side of the road. Very dangerous. No warning lights came on, no alerts. I had the truck towed to Folsom Buick & GMC in Folsom CA where the diagnosed a complete engine failure. The have now had my truck for a full month. They are trying to get GMC to share the cost of the replacement motor. In the meantime, I'm renting a pickup truck so I can continue to work. | Crash: No Fire: No | Unknown |
| Dec 2025 | POWER TRAIN,ENGINE | Ticking noise coming from engine slight metallic noise as well. RPMs drop and when they drop, you can feel power loss constant hunting in the RPMs. Also a weird vibration, not all the time in the front end somewhere. | Crash: No Fire: No | Unknown |
| Nov 2025 | POWER TRAIN,ENGINE | -lifter failure on 6.2 v8 engine, causing damage to camshaft -lost significant propulsion while driving on the highway, nearly avoided being rear-ended by another vehicle due to loss of vehicle propulsion -dealer had to to replace lifter bank and camshaft -no issues, once lifter failed dash lights all lit up | Crash: No Fire: No | Unknown |
| Nov 2025 | SERVICE BRAKES, HYDRAULIC,ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 45-50 MPH, the check engine warning light and the brake warning light illuminated. Additionally, the contact heard an abnormal sound coming from the engine, and the vehicle decelerated. The vehicle was taken to the dealer, where it was diagnosed and determined that all the engine lifters and the camshaft needed to be replaced. The vehicle was repaired. The contact related the failure to NHTSA Action Number: EA25007 (Engine and Engine Cooling). The manufacturer was notified of the failure and informed the contact that the VIN was not under recall. The manufacturer offered to partially cover the cost of the repair. The failure mileage was 107,787. | Crash: No Fire: No | 107,787 |
| Nov 2025 | ENGINE | Engine fan has been constantly running, with engine temp reading around 230 consistently. After driving 5 miles on the interstate it shot up to 260 and said “engine temp overheating, idle engine”. | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | I am Having direct issues with the engine when the vehicle is started and continues while idling or driving at any rate of speed.There's a continuous "Knocking" noise that has concerned me for a while now. My vehicle (2020 GMC Sierra 6.2 liter gas engine) with almost 100,000 miles has been doing this for a while now (at approximately 50,000 miles) and (was documented at the dealership when I made a complaint which included what I considered the vehicle to be using/losing more "oil consumption" than the normal 3-4 quarts between oil change) dating back to 2022 0r 2023 when I was told by the dealership that the amount of oil being used/ lost still fit within the manufacturers specifications. | Crash: No Fire: No | Unknown |
| Nov 2025 | POWER TRAIN | My truck had engine failure while at the dealership getting new tires installed on 11/12/2025. When they started my truck they detected major knocking in my engine the 1st thing in the morning. It unsafe to drive they're telling me my engine needs to be replaced. My engine has 58,000 miles on it. There was no issues with my truck when I drop it off. | Crash: No Fire: No | Unknown |
| Nov 2025 | UNKNOWN OR OTHER | Safety Recall N242454440 Momentary Rear Wheel Lock-Up was issued for 2020 to 2022 GMC Sierra 1500 but mine is not included. I drive a 2020 GMC Sierra 1500. It is experiencing harsh shifting and now there is a feeling in the rear wheels like they are trying to get stuck or hang up. Why is my truck not included? | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | My 2020 GMC Sierra 1500 Denali with the 6.2L L87 V8 just began experiencing a new rough idle with intermittent RPM dips. There are no engine codes or warning lights. Idle drops are noticeable, suddenly began this week. I am concerned due to ongoing NHTSA Engineering Analysis EA25-007 involving this engine. Some owners reported engine failure with little warning. The truck has right over 68,000 miles on it and has had every oil changed performed at a GM dealer. I have had to top off the oil between cycles and always used the recommended oil, being the Dexos Gen 3 due to the truck burning a small amount of oil. More detail on a possible cause. I believe it would be worth investigating the DFM technology. I will be performing a fuel cleaner and possibly a lifter cleaner and/or additive. I would like to tune the truck and turn off the DFM since this is what I have read causes the truck to burn oil and damage the lifters. However, I will wait until this Analysis is completed before deciding to change the truck's stock tunes. | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | The engine failed and started burning oil at a rate of 3 quarts every two weeks. The vehicle is currently at the GMC dealership having the engine rebuilt at a cost of over 15,000. The vehicle has approx. 116,000 miles at time of failure, so it is outside of the manufacturers warranty. The GMC dealership (Fred Anderson Greer) has photos. The engine is a 6.2L but not currently under recall as it is a 2020, the recall includes 2021 - 2024 models. | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | My engine is currently being torn down at the dealership.I heard a ticking noise coming from my engine so I took to the dealership I bought it from and when they did their diagnostics and inspection they said it was a connecting rod bearing failure. | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | This is the 3rd catastrophic engine failure since purchasing this new vehicle from the dealership, the vehicle is currently at the dealership and is available for inspection. The latest diagnostic report has been attached from the dealership for reference. My safety and the safety of others was at risk with each occurrence. The 1st occurred on the interstate when a lifter rod bent causing loss of power with no warning, engine was rebuilt by the dealership. The 2nd occurred on the interstate when a different lifter rod bent causing loss of power with no warning, engine was rebuilt again by the dealership. The 3rd occurred just recently while on a highway. The engine suddenly turned off with no warning. The dash told me to put it into neutral and start again. I had to coast the truck for a long distance after the sudden loss of power in order to attempt to restart the engine. The engine would not start. The diagnostic report from the dealership states "engine is seized tight, maxi fuse is blown, needs engine replacement." | Crash: No Fire: No | Unknown |
| Nov 2025 | POWER TRAIN,SERVICE BRAKES,ENGINE | First my torque converter went out, no warning lights only shaking wehn shifting, I got it replaced already it cost me 2400 Second Warning light service for Brakes, Traction and power steering come on and off. And sometimes truck doesn't brake well and steering wheel feels hard to drive, it has happened while on expressway with family. Third Engine oil low Add oil warning sign comes up alot and I have to add oil, engine has a rough idle now, also when I turn truck on smoke comes out while having a rough idle, recently it started knocking, I haven't moved the truck since than | Crash: No Fire: No | Unknown |
| Nov 2025 | ENGINE | This is a report on an incident that happened a year ago. Vehicle was taken to GMC dealer who replaced the engine at our expense. Seems to be consistent with the problem on newer GMC's that have been covered by a recall. This 2020 is one of three GMC's owned by our company. This expense was in the $12,000 range. (The 2019 experienced similar issues in 2022 and the expense was $2800 ish, and in 2024 another $1200 ish. ) Dash lit up like a Christmas tree, all warning lights on. Stalled, barely moved. | Crash: No Fire: No | Unknown |
| Nov 2025 | ELECTRICAL SYSTEM,UNKNOWN OR OTHER,FUEL/PROPULSION SYSTEM | 1. The vehicle’s emissions system is malfunctioning, specifically the ECM (Engine Control Module) related to the exhaust emissions system. The diagnostic trouble code is P2C7A, indicating the system is not performing as expected. Key components such as the NOx catalytic converters and diesel particulate filter have been repeatedly replaced, but the issue persists. The vehicle and all replaced components are available for inspection upon request. 2. The malfunctioning emissions system has led to an exhaust leak that allowed exhaust gases to enter the vehicle’s cab. This creates a hazardous environment for both the driver and passengers, exposing them to harmful exhaust fumes. In addition to reduced engine performance, poorer fuel economy, and emissions non-compliance, this exhaust leak poses a serious safety risk by compromising the air quality inside the vehicle. Prolonged operation under these conditions could lead to adverse health effects and further mechanical failures that impact vehicle safety. 3. Yes. The dealership has diagnosed the problem multiple times. The emissions components have been replaced under warranty on two separate occasions. The dealer attributed the fault to fuel quality; however, Fuel distributor debunked these claims. 4. The vehicle has been inspected extensively by the dealership with invoiced repair work replacing key emissions control components. 5. The check engine light and Service Engine Soon (SES) light have been illuminated with the diagnostic code P2C7A since the initial identification of the problem which started 3JUN24 | Crash: No Fire: No | Unknown |