Abstract: A control system for fault detection with a control device including a processor having a control program that calculates at least one actuating value signal outputted to an actuator. At two process points in the control program, at least one control point (K) is defined at which a program output value is outputted to form a monitoring signal that is outputted to a monitoring device. The monitoring signal contains at least two signal elements of three possible signal elements. A first signal element represents the control point through which the control program should have directly run before the control point, a second signal element represents the present control point, and a third signal element represents the next control point in the program process. The monitoring device checks the monitoring signals for the correct state, and a state signal can be output as a fault signal.