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.

- Pottstown, PA, USA

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 40 MPH, the vehicle failed to properly respond. There were no warning lights illuminated; however, the message ESC was displayed. The contact stated that the brakes, steering, and a message to check the trailer brakes was also displayed. The contact pulled over to the side of the road and the brake pedal was depressed several times however, the brakes failed to respond, and the vehicle was difficult to control. The vehicle was towed by AAA and then towed to a dealer however, the vehicle was not yet diagnosed. The contact stated that the brakes were inoperable, and the control center was destabilized. The vehicle was not yet repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline. The failure mileage was approximately 125,000.

- Wantage, NJ, USA

My 2020 GMC Sierra brakes failed on May 22nd and ECM and now the engine and transmission are experiencing issues based on the onstar report.

- San Antonio, TX, USA

Parked truck for one hour, engine off. Came back and upon startup, received multiple errors that power steering and ESC required dealer attention. Brake pedal would depress to floor. GMC Sierra 1500 elevation trim

- Bartlesville, OK, USA

Highway driving engine light started flashing, received codes on service ESC and service parking brake. Truck seemed to loose power transmission started shifting very hard, cruse disengaged, lane keep assist stopped working, brakes and steering seemed to act different. When ignition was turned off loud noises from under truck sounded like brakes releasing with loud clunking noise.

- Dadeville, AL, USA

I was going about 15 miles per hour when suddenly all these error codes started popping up, first "ESC malfunction" then trailer brake malfunction, stabilitrak, steering assist reduced, brake system fail, lighs just pop up I do feel like the truck looses some power feels more sluggish, I took it to dealership, they recalibrated the break system and stuff, it fixed the issue temporarily, but the lights keep coming back, sometimes I turn the truck on in the morning and lights are gone, then later on I get all the error codes again while driving it. It started 4 days after I purchased the truck and happens daily since.

- Tolleson, AZ, USA