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 |
|---|---|---|---|---|
| Oct 2025 | ENGINE | The engine failed completely while driving. On the day of the incident, I started my 2020 GMC Sierra 1500 AT4, and immediately upon cranking, the engine began knocking loudly. I shut the vehicle off right away to prevent further damage and called a wrecker service to have it towed to Marianna Chevrolet, GMC. No warning lights or messages prior to the incident. The weather was clear and dry, and the truck was parked on level ground at the time. There were no prior warning lights, leaks, or unusual noises before this event. The vehicle has been well-maintained, with oil changes performed regularly every 4,000 miles at a local auto shop (though receipts are not available). The brakes were replaced earlier in 2025. Marianna Chevrolet, GMC inspected the vehicle and estimated the repair cost at $12,700 due to what appears to be a major internal engine failure. | Crash: No Fire: No | Unknown |
| Oct 2025 | POWER TRAIN | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving approximately 40-60 MPH, the transmission hesitated while depressing the accelerator pedal. A dealer was contacted. The vehicle was taken to the dealer and was diagnosed with transmission control module (TCM) failure. The contact was informed that the TCM needed to be replaced. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 24V797000 (POWER TRAIN); however, the VIN was not included in the recall. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was 75,200. | Crash: No Fire: No | 75,200 |
| Oct 2025 | ENGINE | 43000 miles 2020 gmc sierra with lifter engine issues. Oil change made every 3k miles | Crash: No Fire: No | Unknown |
| Oct 2025 | ENGINE | 6.2L V8 engine in 2020 GMC Sierra 1500 AT4 suffered two lifter failures, which damaged crankshaft and sent metal shards throughout engine and oil. Total engine replacement required. This issue is subject to a recall for 2021 - 2024 model years and the recall should extend to 2020 model years. Vehicle was traded without functioning engine at a significant loss in value for new vehicle, and is not available for inspection. Vehicle was inspected by service department at GMC dealership and traded to a different GMC dealer. No prior indications of problems or warning lights until engine failure occurred while driving. | Crash: No Fire: No | Unknown |
| Oct 2025 | SERVICE BRAKES | On Monday, [XXX], at about 1730 hours was traveling Southbound at 45mph on [XXX] approaching the [XXX] intersection. Vehicle alerted to the following codes on the dash; ESCAPE, Traction Control, Check Engine Light, Brake System Failure, "Do not exceed 62 MPH". I took foot off accelerator and looked up and noticed the traffic light turning red. I applied pressure to the brake and noticed there was no brake pressure at all, and the vehicle continued to roll forward towards the intersection. I put the truck in low gear to slow and continued to pump the brake rapidly. As the truck gradually slowed I turned truck off until it came to a stop. When I restarted the truck the brake hydraulic pressure returned and only the check engine light remained on. I took the truck to Reliable GMC in the Roseville Automall the next morning. The service department claimed the AGM Battery was bad and caused the front brake caliper sensor to throw a low voltage code causing a cascade event of codes throughout the system. The loss of my brakes nearly caused me to enter an intersection unwillingly and could have led to a serious accident. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Oct 2025 | PARKING BRAKE,ENGINE AND ENGINE COOLING,ELECTRONIC STABILITY CONTROL (ESC) | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at approximately 35-40 MPH and hauling a trailer in stop-and-go traffic, there was white smoke coming from the exhaust pipe, and the vehicle started losing power. The contact was able to pull over to the side of the road, where the Electronic Stability Control (ESC) and the check engine warning lights illuminated. The parking brake was engaging and disengaging independently. After turning off the vehicle and waiting for approximately 15-20 minutes, the vehicle was restarted, and the contact drove to the nearest independent mechanic. The mechanic diagnosed the vehicle and determined that the ignition coils needed to be replaced. The vehicle was repaired; however, it was determined that the repair had not resolved the failure. The mechanic then diagnosed the vehicle's cylinder #4 failure. The mechanic was in the process of determining whether the lifter or camshaft had failed. The mechanic determined that the engine might need to be replaced. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 93,000. | Crash: No Fire: No | 93,000 |
| Sep 2025 | ENGINE | Engine misfiring and rough idle with occasional flashing engine light. Dealer said no codes to know what to look for despite replicating issue. Eventually it threw a Cylinder 5 misfire and thus GM dealer was able to look further. They found metal in oil pan and concluded a bearing issue and would need to replace engine. | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN,ENGINE | Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working“. | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN,ENGINE | Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working” | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN,ENGINE | Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working” | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE | Engine timing chains failed at 71,000 miles requiring a $9,700 repair. Warranty covers 5 yr/ 100k miles and was not fully covered by GM since the vehicle was 9 months beyond 5 years, yet still well within the 100k miles. Issue was diagnosed via P0016-00 being set indicating misalignment between crankshaft position sensor and the intake camshaft position sensor. This issue is a known problem with the early LM2 engines, and the timing chain was upgraded in later LM2 engines. Early adopters of the LM2 are left to pay the price for a defective part. | Crash: No Fire: No | Unknown |
| Sep 2025 | ENGINE | The engine coolant control valve on my 2020 GMC Sierra 1500 with the LM2 Duramax diesel failed. The failed part is still in my truck, which remains at the dealership awaiting replacement. The repair is delayed due to the part being on nationwide backorder, further highlighting that this is a widespread issue. When the valve failed, the truck entered reduced engine power mode while I was traveling on the interstate. This limited my speed to about 40 mph while climbing a hill. The sudden loss of power in high-speed traffic created a serious safety hazard, as it significantly increased my risk of being rear-ended or involved in a collision with faster-moving vehicles. I drove the truck directly to the dealership after the incident, where the problem was immediately confirmed. The issue was diagnosed and confirmed by the dealership, which identified the coolant control valve as the failed component. To my knowledge, GM has not yet inspected this specific failure. Prior to the loss of power, the truck displayed a “Reduced Engine Power” warning message and the check engine light on the dashboard. These warnings appeared at the time of the failure. Importantly, GM has already acknowledged this issue by issuing Special Coverage N252508341 for 2021 and 2022 GMC Sierra 1500 trucks with the same LM2 engine and the same coolant control valve part numbers. However, the 2020 models (like mine) were excluded from that program despite using the identical part and engine configuration. | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM | 2020 gmc sierra 1500 elevation 5.3l engine. Lifter failure due do faulty design I’m afm/dfm systems. | Crash: No Fire: No | Unknown |
| Sep 2025 | POWER TRAIN,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle jerked abnormally while depressing the accelerator pedal. A dealer was contacted. The vehicle was taken to the dealer, and the technician informed the contact that the failure might be related to the engine or transmission; however, the contact was informed that the vehicle needed to be inspected to determine the cause of the failure. The vehicle was not repaired. The contact stated that the failure had occurred several times. The manufacturer was notified of the failure and informed the contact to file a complaint with the NHTSA Hotline. The approximate failure mileage was 41,248. | Crash: No Fire: No | 41,248 |
| Sep 2025 | STEERING | The contact owns a 2020 GMC Sierra 1500. The contact stated that upon start the vehicle, the vehicle lost power steering functionality. The messages “Service Power Steering”, “Power Steering Disabled” were displayed, and ESC warning light was illuminated. The vehicle was taken to a local dealer where it was diagnosed, and the contact was informed that further diagnostic tests were needed to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 115,000. | Crash: No Fire: No | 115,000 |
| Sep 2025 | POWER TRAIN | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission experienced rough gear shifts. Additionally, the vehicle shuddered while driving. The vehicle was taken to an independent mechanic, who was unable to diagnose the vehicle due to a lack of diagnostic equipment. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 120,000. | Crash: No Fire: No | 120,000 |
| Sep 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 40 MPH, there was an abnormal knocking sound coming from the engine compartment. The contact stated that several unknown warning lights were illuminated, and several messages were displayed. The vehicle was driven to the side of the road to safety and turned off. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure milage was approximately 76,000. | Crash: No Fire: No | 76,000 |
| Sep 2025 | SERVICE BRAKES, HYDRAULIC,ENGINE,BACK OVER PREVENTION | The contact owns a 2020 GMC Sierra 1500. The contact stated that on several occasions while the vehicle was started, the check engine, brake system, and another unknown warning light illuminated. Additionally, the messages brake system failure, steering wheel failure, low oil, and two other unknown messages were displayed. The contact also stated that the rear-view camera remained displayed while shifted into drive, and the instrument panel failed to operate as intended. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 65,000. | Crash: No Fire: No | 65,000 |
| Sep 2025 | ENGINE | Vehicle: 2020 GMC Sierra Denali 1500 (VIN: [XXX] ) Description of the Problem: My 2020 GMC Sierra Denali has developed serious engine problems that create unsafe driving conditions. On [XXX], I documented loud knocking and clicking noises coming from the engine. The vehicle also shows warning lights and unpredictable performance. Because of these defects: •I cannot safely drive the truck without risk of engine failure while on the road. •The noises and mechanical issues raise concerns about potential loss of power, stalling, or catastrophic engine damage at highway speeds. •No independent mechanic will touch the vehicle because of the complexity and risk of the defect, leaving me stranded. General Motors has refused to take responsibility, and the BBB AUTO LINE denied my case due to mileage, but the defect itself is unrelated to mileage or normal wear. This is a manufacturer defect that creates a safety hazard for me, my family, and other drivers on the road. What I’m Requesting: I am asking NHTSA to investigate this issue with GMC Sierra models, as these engine defects make the vehicle unsafe to operate and could lead to accidents if the engine fails while driving. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) | Crash: No Fire: No | Unknown |
| Sep 2025 | STEERING | My extended warranty expired. I got my oil changed at valvoline and then 2 days later my power steering stopped working and I’m getting multiple dash messages of other systems malfunctioning. Did gmc cause this to get me to come back to their service center. It seems very suspicious | Crash: No Fire: No | Unknown |
| Aug 2025 | ENGINE,FUEL/PROPULSION SYSTEM | My 6.3l v8 Started having a slight misfire while driving. Took vehicle to a mechanic and was advised to change the spark plugs, changed spark plugs, spark plug wires, and ignition coil packs while still experiencing sudden misfires while driving. Starting to consider the 6.2L L87 collapsing cylinder issue. | Crash: No Fire: No | Unknown |
| Aug 2025 | STEERING,ELECTRICAL SYSTEM,SERVICE BRAKES | Was driving down the freeway around 65 miles an hour attempted to pass a truck when the steering started wobbling the ABS that EMS and the breaking system came on with the check engine light almost had no control and barely avoided having an accident the only way it went back to normal was slowing down. | Crash: No Fire: No | Unknown |
| Aug 2025 | SERVICE BRAKES | My vehicle displayed numerous brake failure codes and limited my speed to 43mph. When taken into my local GMC dealer the diagnostics I was given were a bad/leaking master cylinder. This vehicle has 16,200 miles on it and was never used for towing or hauling. The brakes are hard and brake assist has clearly failed. I’ve found numerous recalls and issues with other year vehicles from GMC, yet they are denying any liability on my vehicle. They want over $3000 to replace the master cylinder even though there’s no physical leak observed via fluid loss. This is a major safety concern when a major brake component fails on such a low mileage vehicle. This truck also has a well known seal leak on the rear window that causes mold to grow inside of the vehicle cabin. Apparently no one has died yet so they have not been forced to put out a recall. Consumers should not be forced to spend thousands of dollars on major components on such low mileage vehicles. Especially when it comes to safety items like braking. I’ve researched this for hours and have found this has been a known issue on these 2020 models many people. Some even brand new after driving them off the dealership lot. Clearly there is an issue and the manufacturer refuses to address it. | Crash: No Fire: No | Unknown |
| Aug 2025 | POWER TRAIN,ENGINE | I have a 2020 sierra 1500 6.2 with 86,000 miles. I have only had this truck 6 months. This was inspected before I purchased with no engine issues. Since purchasing we have driven less than 6000 miles. While driving my vehicle the rod in the engine failed and started knocking. I am a mechanic and I am GMC master certified. Both myself and the owner of the shop I work at diagnosed the vehicle with a bad engine. We looked at the recall for the 6.2 engine and noticed that many of the 2020 vehicles with this engine have the same issue that is currently being recalled for this specific engine. I called GMC and they won’t fix the issue that the vehicle is having. They won’t perform the recall and again I have only had this vehicle for 6 months and with 86,000 miles should not be having this issue. I am GMC certified and told them that I looked into the recall and they them selves state that some of the defective engines got out into the 2020 models. | Crash: No Fire: No | Unknown |
| Aug 2025 | UNKNOWN OR OTHER | My doors will no longer lock or unlock, using the key fob or the lock/unlock buttons in the vehicle. This is a widely known issue for GMC Trucks, once you search for it. At around 50K Miles, the door actuators just quit working. So, if I have kids in my truck, I can't unluck the doors to get them out unless I climb through the truck, and have to manually do same to lock the doors to drive with kids in the car. There isn't a key hole for the back doors, so this can't be done at all outside the car. The doors are supposed to automatically lock when the truck is put in gear. Mine won't lock even when I push the button to lock. I just had this confirmed at the dealer. I also spoke to GMC and was told that it wasn't their responsibility. This is a genuine safety issue, and happens on these trucks a LOT. | Crash: No Fire: No | Unknown |