The contact owns a 2020 Tesla Model X. The contact stated while driving approximately 55 MPH, the self-driving mode disengaged unintendedly. There was no warning light illuminated. The vehicle was taken to a Tesla Service Center, where it was diagnosed that the self-driving system had completely failed. The Service Center determined that the self-driving computer needed to be replaced. The vehicle was in the process of being repaired. The manufacturer was notified of the failure. The failure mileage was approximately 76,000.