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.