2021 GMC Acadia Forward collision avoidance Problems

“My vehicle stops working while in traffic when the auto stop is engaged. The abs, parking brake, and dash flashes prior to the engine stopping. I have been to the dealership multiple times and they are never able to recreate the issue. The check engine light codes produced are P0014 and c0800-03.”

“On March 27, 2026, I experienced a complete brake failure while driving a 2021 GMC Acadia in a school zone at approximately 3:00 PM. When I pressed the brake pedal, the vehicle did not respond. I attempted multiple times, including using the emergency brake, which did not activate immediately. The vehicle remained in motion for several minutes in an area with children and parents present. The emergency brake only engaged after approximately 30–45 seconds of repeated attempts. I was forced to steer off the road to avoid a collision. …”

“While driving down a busy road automatic braking engaged for no reason causing the Acadia to abruptly come to a dead stop in the middle of the road with nothing in front of me. Red collision lights came on at the same time as braking with no prior warnings. Could not get the car to move for a few minutes (when giving gas there were grinding sounds) then the braking system let up. Drove for another few minutes and it did it again. Called GM and WE had to figure out how to get the car to the dealership with a major safety issue. Took the car in and it was throwing B390F, U0184, B395A codes. …”

“The contact owns a 2021 GMC Acadia. The contact stated that while driving at 30 MPH, traffic stopped abruptly, and the brake pedal was depressed to the floorboard; however, the vehicle continued to accelerate while the Forward Collision Avoidance warning feature activated with a red warning light on the instrument panel. The contact attempted to steer off the road to avoid a collision; however, the vehicle crashed into the vehicle ahead, resulting in a three-vehicle collision. The air bags did not deploy upon impact. …”

“Was on the interstate driving when the emergency brake engaged causing the car skid the tires and almost completely coming to a stop in heavy traffic. Shortly after this the transmission had issues which caused the car to be undrivable and had to be towed. The dealership had the car for over a month and replaced the TCM. There were no other warnings prior to this.”