The invention concerns a device for controlling an autonomous vehicle in connection with a risk of accident. The device comprises a processor unit that is adapted so as to receive one or a plurality of sensor signals S 1 -S k that indicate the state of at least one system or one component in the vehicle. The processor unit is adapted so as to analyze the state based on a first set of rules, and to generate an error signal in dependence upon the results of the analysis, whereupon the error signal indicates a fault in the system or a component, decides on at least one action for the vehicle at least according to a second set of rules for said fault and a third set of rules for the traffic system in which the vehicle is operating; and to generate one or a plurality of control signal(s) SCONTR that realize the action or actions and send SCONTR to at least one control system in the vehicle, whereupon the vehicle is controlled in accordance therewith. The invention also concerns a method for controlling an autonomous vehicle.