GMC Sierra Complaints (2020)

626 consumer complaints on file.

#11691983October 7, 2025
ELECTRICAL SYSTEM, EXTERIOR LIGHTING, STEERING
I have taken the vehicle to my local dealership six times. The tailgate started opening and the headlights were blinking on and off. This happened 3 months after I bought it. The dealership told me they changed the tailgate switch and they said there wasn’t anything wrong with my lights. Two weeks after the dealership said they changed the tailgate switch, the tailgate started opening and closing. The lights also stopped working driving down the road at night. This happened 3 different times at night. The tailgate opened when I was pulling a trailer and it caved in and I had to pay to have it repaired. The dealership said it wasn’t their problem. During this time the power steering fluid was leaking under my steering wheel and ruined my carpet. The dealership has yet to acknowledge that problem. I still have to put power steering fluid in the truck every week and my interior is ruined. The tailgate is still opening on its own. I had to start charging my batteries up every morning because they were dead. I got up one morning and the batteries were dead and the truck wouldn’t start. I had to buy a new $300 key. Took it back to the dealership for an appointment. The truck sat there for a week and I called for an update and they didn’t even remember the truck was there. It still sat there 4 days after that. They told me the truck needs new batteries and it wasn’t under warranty. I spent $1000 on 2 batteries. Tailgate is still going down. The lights are still going on and off. And then the lights and the locks will go on and off while the truck is parked and turned off. And now the new batteries are becoming weak and I am having to get the truck jumped off several times. I have had the truck at the dealership 6 times and they still haven’t fixed anything. When they have my truck I am losing money because I am a business owner and I use my truck for work. I lost all of my tools. I have lost time and money because the dealer has yet to help and do their job. I need help GM
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11690794October 1, 2025
ENGINE AND ENGINE COOLING, ELECTRONIC STABILITY CONTROL (ESC), PARKING BRAKE
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
Injuries:
0
Deaths:
0
#11690818October 1, 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
Injuries:
0
Deaths:
0
#11689905September 26, 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
Injuries:
0
Deaths:
0
#11689351September 24, 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
Injuries:
0
Deaths:
0
#11689543September 24, 2025
ENGINE, POWER TRAIN
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
Injuries:
0
Deaths:
0
#11689544September 24, 2025
ENGINE, POWER TRAIN
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
Injuries:
0
Deaths:
0
#11689546September 24, 2025
ENGINE, POWER TRAIN
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
Injuries:
0
Deaths:
0
#11689015September 22, 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
Injuries:
0
Deaths:
0
#11688635September 20, 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
Injuries:
0
Deaths:
0
#11688359September 19, 2025
ENGINE, POWER TRAIN
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
Injuries:
0
Deaths:
0
#11687856September 17, 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
Injuries:
0
Deaths:
0
#11687414September 15, 2025
ENGINE
The catalytic converter failed at 93,000 miles, and 64 months. GM says it is out of warranty.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11686873September 12, 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
Injuries:
0
Deaths:
0
#11685689September 8, 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
Injuries:
0
Deaths:
0
#11685227September 5, 2025
ENGINE, BACK OVER PREVENTION, SERVICE BRAKES, HYDRAULIC
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
Injuries:
0
Deaths:
0
#11684768September 3, 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
Injuries:
0
Deaths:
0
#11684363September 2, 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
Injuries:
0
Deaths:
0
#11683304August 26, 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
Injuries:
0
Deaths:
0
#11682879August 25, 2025
SERVICE BRAKES, STEERING, ELECTRICAL SYSTEM
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
Injuries:
0
Deaths:
0

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