2020 GMC Sierra 1500 Complaints

SUSPENSION,POWER TRAIN — Filed 07/02/2026

My truck transmission beed jerking off and on for over a year. One time it lose power when i was driving and could have caused an accident. I took it to the dealership and they said i new a new transmission for $12000. Something just doesn’t seem right about this! I brought a brand new truck thats unsafe and its no recall for my model but other models with the same issue had a recall. I would just like some answers. I feel like i brought a lemon. Thanks for listening.

SERVICE BRAKES,ENGINE — Filed 07/12/2026

The contact’s mother-in-law owns a 2020 GMC Sierra 1500. The contact stated that while her brother-in-law was starting the vehicle, the brake, service engine, and engine warning lights illuminated and the vehicle failed to start. The contact stated that the failure was associated with NHTSA Action Number: EA25007 (ENGINE, ENGINE, AND ENGINE COOLING) and PE25001 (ENGINE, ENGINE, AND ENGINE COOLING). The vehicle was towed to a local dealer, where it was diagnosed with engine failure. The vehicle was not repaired. The owner was scheduled to meet with the dealer to discuss the issue. The manufacturer was contacted and confirmed that there were no open recalls on the VIN related to the failure. The failure mileage was approximately 45,000.

ENGINE AND ENGINE COOLING — Filed 07/02/2026

The contact owns a 2020 GMC Sierra 1500. The contact stated that while accelerating from a complete stop on several occasions, an abnormal clicking sound was heard from the engine compartment. The vehicle was taken to the dealer, where it was diagnosed with a failed fan belt pulley. The vehicle was not repaired. Additionally, while parked on one occasion, an abnormal clicking sound and a loud bang were heard from the engine compartment, and the vehicle stalled. The contact attempted to restart the vehicle, but it failed to turn over. The vehicle was taken to the dealer, where a failed valve spring was diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 75,127.

ENGINE — Filed 09/01/2025

The cam shaft bearing failed under normal driving conditions. Many of the service engine lights including brakes and primary service engine light came on after the cam shaft bearing failure. The engine was replaced by a GM dealership at 65,000 miles and was inspected to determine the cam shaft bearing failed. Luckily the engine failed at a speed of 35 mph on an off ramp, as a complete engine failure on the highway could have been much more dangerous. Following the replacement of the engine, within 500 engine miles, O2 sensors in the catalytic converter were replaced and ultimately the catalytic converter had to be replaced as well.

ENGINE — Filed 06/01/2026

The engine had a critical failure at 49,000 miles. It was replaced under the drivetrain warranty. That came with a 12 Month, 12,000 mile warranty. Now I have a SECOND engine failure at 59,000 Miles. This will come with only a 12 month 12,000 mile warranty because it is NOT under recall. ALSO my transmission is now slipping and they are replacing the Valve Body. They had my truck for 4 months the first time and one month this time. These are the exact same issues with 2021 - 2025 GMC 6.2L and 10 Speed Transmissions. If I the issue had happened 6 months later I would have NO warranty. I want a recall on 2020's please.

ENGINE — Filed 06/19/2026

My 2020 GMC Sierra 1500 Denali with L87 6.2L V8 suffered a catastrophic, silent seizure at 108,000 miles. Driving at highway speeds, warning light stating shift to neutral and press start, engine completely shut off and would not turn back on. I was in the car with my 3 children about to make a turn across a 4 lane highway. I was able to recognize that there was power loss quickly enough that we were safely within the turn median, and fortunately a "good samaritan" stopped to assist us in getting across the highway into a parking lot. I hate to think what would have happened had this power loss occurred during the turn. There was no warning light, sound or other issue prior to this occurring. The vehicle has been meticulously maintained with all services occurring at my local GMC dealership. We had the truck towed to the dealership who confirmed the engine needs to be replaced.

POWER TRAIN — Filed 12/15/2025

The contact owns a 2020 GMC Sierra 1500. The contact stated that upon taking the vehicle to the dealer for a transmission fluid flush and refill, the contact was informed that the transmission was inoperable, and the vehicle could not be driven to the residence. The dealer determined that the torque converter needed to be replaced. The dealer replaced the torque converter and advised the contact to drive over 1,000 miles for the issue to self-correct. The contact stated that the vehicle continued to shudder and drive bumpy while driving after 1,000 miles. The vehicle was taken back to the dealer, where the torque converter was replaced a second time; however, the failure persisted. The dealer informed the contact that the diagnostic test results were sent to the warranty company for the transmission replacement approval. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 85,165.

ENGINE — Filed 05/10/2026

• While driving a loud popping and clicking noise started coming from the engine and the truck started shaking. The vehicle is available for inspection • It was a busy two lane road and I had to continue about 30mph under the speed limit to safely get off the roadway • upon start up the engine clicks and pops with rough idle and the truck shakes. A mechanic looked at it and stated it sounds like a lower rod bearing noise • No further inspections have been done • A Service ESC warning popped up when the engine started making noise during the incident. The truck had been taken in twice for rough idle and engine noises prior to 100k miles, but the dealership stated that the noise and feel was normal for the 6.2L engines

ENGINE — Filed 06/15/2026

While driving at night, a low oil pressure warning light illuminated on the dashboard. The following morning, I checked the oil level using the dipstick, which indicated a normal reading. Based on this, I proceeded to drive the vehicle. Shortly after departing, the engine began knocking severely. I immediately stopped and returned home. The vehicle was towed to a GMC dealership for diagnosis. The dealership determined that the engine had experienced catastrophic failure and required complete replacement. I was quoted $11,000 for the repair.

POWER TRAIN — Filed 06/09/2026

The contact owns a 2020 GMC Sierra. The contact stated while driving at an undisclosed speed, the transmission hesitated and shifted unusually rough. No warning lights were illuminated. The vehicle was taken to an independent mechanic where it was diagnosed with a transmission valve issue. The contact was advised that the power train software needed to be updated. The contact was informed of an unknown recall; however, the VIN was not associated with a recall related to the failure. The vehicle was not repaired. The dealer was made aware of the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 88,000.

ELECTRICAL SYSTEM — Filed 05/30/2026

Fire started under passenger side front seat dashboard when rear defrost was turned on.

STEERING,POWER TRAIN,ENGINE — Filed 02/17/2026

Hi, was driving Vehicle GMC 1500 Denali, vehicle Lost power, all Lites lite up on Dashboard, Vehicle Just lost power and i swerved off Road and sideswiped a Plant Holder on side of Road, damaging side passenger Rear door. I bought the truck to GMC Rvc and they said vehicle Blew Cam shaft and Lifters. I explained to them I'm very concerned for others safety in these Vehicles with the 6.2 Engine. Someone is going to get Killed or even a family. I did look up this vehicle its not listed in Recall, but this vehicle has same engine as ones in Recall. Rvc Gmc issued me a bill for repairs for the amount of $8185.20 and they stated they took 3k off invoice. I did Pay total Invoice....I'm just asking you to please look into this as this is defiantly an issue and this year should be listed on Recall as well.. Thanku for at least looking at this. My cell is [XXX] if you need to reach us...Thx.... INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

ELECTRICAL SYSTEM,ENGINE — Filed 07/08/2022

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.

ELECTRICAL SYSTEM,STRUCTURE — Filed 12/01/2021

Tailgate releases on its own while parked, without the use of the switch. Tailgate released on its own with my trailer attached while parked on many occasions. The result of the Tailgate releasing caused damage to the upper section of the Tailgate, the "kicker speaker system" in the Tailgate and Tailgate switch located on the upper section of the Tailgate. There also have been multiple times when attaching the trailer that the Tailgate has released and struck me in the head. The Tailgate also fills with water during rain, and carwashes. The damage caused by the Tailgate releasing is a dent on the upper section of the multi-pro Tailgate and rust and malfunction of the " kicker speaker system " as well as the occasional hickey and headache on my head. The Tailgate has filled up with water since I purchased it new in December of 2020 which I believe has been electricly shorting the Tailgate switch/button releasing the Tailgate randomly. Due to my particular 2020 GMC Sierra 1500 AT4 CarbonPro having the " kicker speaker system " in my opinion makes the Tailgate so much heavier than one without it that it made the damages such as the dent in the face above the Tailgate switch much worse than trucks without it also causing more water to enter the Tailgate causing more damage to the switch and components of the " kicker speaker system ", such as the amp and buttons for it not to mention my head on several occasions.

AIR BAGS — Filed 04/02/2024

The contact owns a 2020 GMC Sierra. The contact proceeded through the intersection when a vehicle crashed into the contact's driver's side door and wheel at unknown speeds. The contact stated that the other vehicle crashed into two vehicles, then crashed into the contact's vehicle and stopped. The contact stated that the police report stated that the vehicle that crashed into the contact was constantly moving at the posted limit of 50 MPH. The air bags did not deploy. The contact was treated for a left shoulder sprain and swollen right hand, however, it was unknown if other passengers sustained injuries. A police report was filed. The vehicle was towed to a body shop but the vehicle was not repaired. The failure mileage was approximately 34,800.

AIR BAGS — Filed 12/22/2023

Driving on state highway at posted speed. A deer ran into the right front and side of vehicle. Side airbags deployed. When the right side airbag deployed, it burned a hole in my passengers winter coat that completely went through the right sleeve forearm and scorched the sweatshirt that she was wearing under the coat. Smoke was visibly apparent in the cab of the vehicle. We thought the truck was on fire , then finally determined it was the sleeve of here coat.

AIR BAGS — Filed 05/04/2023

The contact owned a 2020 GMC Sierra 1500. The contact stated that while he was stopped in traffic, he was rear-ended, which caused him to crash into the vehicle in front of him. The contact stated that smoke was seen coming from the air bag; however, the air bags failed to deploy. The contact had not sustained injuries. A police report was filed. The vehicle was towed to a salvage yard. The manufacturer was not made aware of the failure. The approximate failure mileage was 64,000.

FUEL/PROPULSION SYSTEM — Filed 11/10/2022

The fuel pump module failed according to the dealer at 34000 miles . Car stop while driving. Cranks but no start. After resting it for hours I was able to start. Drive couple of miles about 39000 miles it stops middle of driving and couldn’t start anymore but still cranks

VEHICLE SPEED CONTROL — Filed 08/09/2021

I investigated and Unintended Acceleration crash that occurred on 8-9-2021. The vehicle had just left a body shop where it had repairs to the left front of the vehicle near the ECM. The driver reported the vehicle would not slow down. He face timed a witness and showed her his foot was on the brake and not the accelerator pedal collaborating his statement. The 2020 GMC accelerated to 93 miles per hour crashing into the back of a Cadillac Escalade. Upon impact the fuel tank of the Cadillac exploded igniting both vehicles on fire and burning a fed-x truck that was folded in half from the sever impact. The EDR report stated the brakes were applied fully for a full 5 seconds prior to the crash while the vehicle was still accelerating. The accelerator was reading a constant 57% during the lead up to the crash and the brake rotors showed heat related glazing from excessive braking. The engine torque was also at 1023NM leading up to impact collaborating Unintended Acceleration further. Based on the evidence gathered my opinion is there was a short in the components in the left front of the vehicle most likely the ECM harness that caused the crash. It is unknown if the damage was caused by the previous crash, the body repairs or a manufacture defect at this time. The radiator had also just been replaced so moisture could have contributed to the malfunction. If moisture shorts APP-1 to APP-2 the safety systems can fail to detect a single fault because it causes redundant faults

SERVICE BRAKES — Filed 08/09/2021

This vehicle was involved in a fatal crash when it rear ended an SUV stopped at a red traffic light. The driver alleges mechanical failure of the brakes. Police performed a vehicle download which captured 5 seconds of pre-accident data. The download shows the accelerator pedal was fixed at exactly 57% the entire 5 seconds pre-crash while the driver simultaneously applies the brakes the entire 5 seconds. A city bus captured the crash on a dash camera. Despite the driver desperately applying the brakes, the vehicle's speed continued to increase and the driver was unable to avoid the collision, and burst into flames upon impact. The vehicle mileage is less than 2,500.

AIR BAGS — Filed 05/14/2021

Airbags failed to deploy after striking a street light pole head-on. The impact hit just right of dead center of the grille and shoved the front end back approximately 2 feet into the engine. There were no dash lights or warning lamps illuminated before the collision. I have notified GM and received a case number. I also have filed an insurance claim and the vehicle has been inspected by a reputable body shop and has been deemed a total loss. A police report was also filed. The vehicle is scheduled to be picked up by the insurance company on 5/18/21.

AIR BAGS — Filed 12/19/2020

TL* THE CONTACT OWNS A 2020 GMC SIERRA 1500. THE CONTACT STATED THAT WHILE DRIVING APPROXIMATELY 35 MPH THE DRIVER LOST CONTROL OF THE VEHICLE AND DROVE OFF THE ROAD AND DOWN AN EMBANKMENT BEFORE CRASHING TO THE GROUND. DURING THE CRASH THE VEHICLE SUSTAINED SEVERE DAMAGE TO THE FRONT END BUT THE AIR BAGS DID NOT DEPLOY. THE DRIVER SUSTAINED HEAD AND SHOULDER INJURIES WHICH REQUIRED MEDICAL TREATMENT. THE VEHICLE WAS TOWED AWAY. NO POLICE REPORT WAS TAKEN. THE CAUSE OF THE FAILURE WAS NOT DETERMINED. THE LOCAL DEALER MAYSE EARNHARDT AUTO GROUP LOCATED AT 2032 S ELLIOTT AVE, AURORA, MO WAS NOTIFIED OF THE FAILURE. THE MANUFACTURER WAS NOT CONTACTED. THE FAILURE MILEAGE WAS 10,000.

ELECTRONIC STABILITY CONTROL (ESC),SERVICE BRAKES,ENGINE — Filed 05/22/2020

MY 2020 GMC SIERRAS BRAKES FAILED ON MAY 22ND AND ECM AND NOW THE ENGINE AND TRANSMISSION ARE EXPERIENCING ISSUES BASED ON THE ONSTAR REPORT.

STEERING,SERVICE BRAKES — Filed 05/21/2020

TL* THE CONTACT OWNS A 2020 GMC SIERRA. THE CONTACT STATED THAT WHILE DRIVING AT 25 MPH, THE SYSTEM BRAKE FAILURE WARNING MESSAGE ILLUMINATED ON THE INSTRUMENT PANEL. ONCE THE WARNING LIGHT ILLUMINATED, THE CONTACT EXPERIENCED COMPLETE BRAKE AND STEERING FAILURE. THE CONTACT WAS ABLE TO STEER THE VEHICLE INTO A CURB TO SLOW DOWN THE VEHICLE AND AVOID A POSSIBLE COLLISION WITH ANOTHER VEHICLE. THE CONTACT STATED THAT HE HAD SUFFERED PAIN TO HIS LEFT SHOULDER BLADE AND LEFT KNEE; HOWEVER, HE DID NOT SEEK MEDICAL ATTENTION DUE TO COVID-19. AFTER EXPERIENCING THE FAILURE, THE CONTACT HAD THE VEHICLE TOWED TO DESERT SUN MOTORS, INC. (2600 N WHITE SANDS BLVD, ALAMOGORDO, NM 88310) WHERE THEY CLEARED THE SYSTEM'S COMPUTER AND INFORMED THE CONTACT THAT THEY FOUND NO DEFECTS WITH THE VEHICLE. UPON RETURN OF THE VEHICLE, HE EXPERIENCED ANOTHER BRAKE FAILURE AS THE CHECK ENGINE LIGHT ILLUMINATED WHILE DRIVING AT 55 MPH. DUE TO THE FAILURE, THE CONTACT WAS FORCED TO RUN A RED LIGHT AND DRIVE UP AN INCLINE IN ORDER TO BRING THE VEHICLE TO A COMPLETE STOP. THE VEHICLE WAS THEN TOWED SHAMALEY BUICK GMC (955 CROCKETT ST, EL PASO, TX 79922) WHERE IT REMAINED IN THEIR POSSESSION. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE AND A FIELD INSPECTOR WAS SENT TO INSPECT THE VEHICLE. THE CONTACT STATED THAT KNOW BRAKE FAILURE CODES WERE DETECTED. THE CONTACT STATED AFTER THE THIRD FAILURE THE VEHICLE WAS TOWED TO SHAMALEY GMC WHERE IT WAS AWAITING DIAGNOSIS. THE VEHICLE HAD YET TO BE REPAIRED. THE FAILURE MILEAGE WAS UNKNOWN.

SERVICE BRAKES — Filed 03/03/2020

THE ABS SYSTEM FAILED WHILE DRIVING DOWN THE ROAD CAUSING THE BRAKES TO LOCK UP AND CAUSED THE TRUCK TO SPIN OUT OF CONTROL NEARLY CRASHING INTO ANOTHER VEHICLE AND JUMPING OVER THE CENTER DIVIDE INTO ONCOMING TRAFFIC.