NHTSA Complaint #11495342 — 2019 GMC SIERRA 1500

The truck has 50,000 miles, purchased new. I don't tow or go off road. I take it to the dealer every 5,000 miles. While driving 65-70mph on the interstate (4-lanes), my dash lit up with five messages and the "Brake, Traction Control and Engine" lights illuminated. I applied brakes but the pedal went to the floor and the steering veered to the left causing me to move out of my lane. The truck then went to limp mode and I was unable to go above 43mph the remainder of the trip home. After taking it to my dealer the next day, I was told they "found air in the brake fluid system due to secondary seal failure in brake master cylinder, and was quoted a new cylinder (PN 86788482) for $1708.06. RESPONSE TO QUESTIONS: >Component failure: brake master cylinder (eBoost Brake Unit Assembly) / Brake System Failure >It was just me in the vehicle - brake failure on the highway put me and others on the road at major risk >Yes - After paying to diagnose, I was told this was brake master cylinder failure. ...GM issued a Customer Satisfaction Program (N202324120) for a limited number of MY2021 Silverado/Sierra trucks (mine is a MY2019) for dealers to replace the eBoost brake unit assemblies due to failure >Part has not been inspected by my insurance rep./I do not know if anyone else has inspected >The warnings illuminated on the dash at the time of brake failure while on the interstate 1. "Service ESC" 2. "Service Trailer Brake System" 3. "Steering Assist Is Reduced Drive with Care" 4. "Service Brake Assist" 5. "Brake System Failure 43 MPH Top Speed" 6. Also, the BRAKE, Traction Control and Engine lights illuminated