This invention relates to a method for controlling a motor vehicle drivetrain system which has a drivetrain as well as a combustion engine for driving this drivetrain and an electronic engine control unit as well as an electronic transmission control unit, whereby, if the electronic transmission control unit fails or when the electronic engine control unit loses communication with the electronic transmission control unit, the permissible engine torque of the combustion engine is limited, as well as a safety system for a motor vehicle by means of which the method is controlled, as well as a motor vehicle with such a safety system.