Method for authenticating a vehicle with a service unit by way of a central computer unit external to the vehicle, wherein - an authentication unit is provided in the vehicle , - an initial value (Nr) is transmitted from the service unit to the authentication unit , - depending on the initial value (Nr), the authentication unit reads a request command from a request table stored in the authentication unit , - the request command is output by the authentication unit to an interface of the vehicle , - in the vehicle , a vehicle component executes the request command and generates an output value (R) in response, - the output value (R) from the interface is received by the authentication unit , - the authentication unit uses a predetermined check value function (h) to generate a vehicle check value (Hr) from the output value (R), - the vehicle check value (Hr) generated from the output value (R) and the initial value (Nr) are transmitted to the central computer unit , - depending on the initial value (Nr), the central computer unit reads a characteristic value from a characteristic value table stored in the central computer unit , - the central computer unit uses the predetermined check value function (h) to generate a further vehicle check value (Hr') from the characteristic value , - the vehicle check value (Hr) generated from the output value (R) and the further vehicle check value (Hr') generated from the characteristic value are checked with one another for a match by the central computer unit , and - in the event that the vehicle check values (Hr) match, the central computer unit sends a predetermined enable signal to the service unit . - an authentication unit is provided in the vehicle , - an initial value (Nr) is transmitted from the service unit to the authentication unit , - depending on the initial value (Nr), the authentication unit reads a request command from a request table stored in the authentication unit , - the request command is output by the authentication unit to an interface of the vehicle , - in the vehicle , a vehicle component executes the request command and generates an output value (R) in response, - the output value (R) from the interface is received by the authentication unit , - the authentication unit uses a predetermined check value function (h) to generate a vehicle check value (Hr) from the output value (R), - the vehicle check value (Hr) generated from the output value (R) and the initial value (Nr) are transmitted to the central computer unit , - depending on the initial value (Nr), the central computer unit reads a characteristic value from a characteristic value table stored in the central computer unit , - the central computer unit uses the predetermined check value function (h) to generate a further vehicle check value (Hr') from the characteristic value , - the vehicle check value (Hr) generated from the output value (R) and the further vehicle check value (Hr') generated from the characteristic value are checked with one another for a match by the central computer unit , and - in the event that the vehicle check values (Hr) match, the central computer unit sends a predetermined enable signal to the service unit . <EOS>