Method for controlling a brake system of a motor vehicle with increased safety requirements

A brake system of a motor vehicle comprising:

• an electric machine having a rotor and a rotor position sensor;
• a control unit having instructions for:
• controlling the electric machine in a normal operating mode, wherein a current rotor position of the electric machine is determined using the rotor position sensor;
• checking the functionality of the rotor position sensor;
• checking whether a first test condition is met upon detection of a sensor error of the rotor position sensor;
• changing the controlling of the brake system from the normal operating mode into a safety operating mode when the first test condition is met;
• controlling the brake system with the control device in the safety operating mode;
• checking whether a second test condition is met in the safety operating mode;
• controlling the brake system further with the control device in the safety operating mode when the second test condition is met;
• changing the controlling of the brake system to a fallback operating mode when the second test condition is not met;
• and
• controlling the brake system with the control device in the fallback operating mode.