Overvoltage protection circuit for a control unit for a vehicle, wherein the overvoltage protection circuit has the following characteristics: an input terminal for applying an electrical input voltage (U in), a test terminal for applying an electrical test voltage and an output terminal for providing an electrical output voltage (U out) for supplying the control unit; a reference device which is configured to use the input voltage (U in)to provide a reference voltage (U out); a splitting device which is configured to use the output voltage (U out) to provide a partial voltage, wherein the splitting device has a first electrical splitting resistance and a second electrical splitting resistance, wherein a first terminal of the first splitting resistance is connected to the output terminal, wherein a second terminal of the first splitting resistance is connected to a first terminal of the second splitting resistance, wherein a second terminal of the second splitting resistance is connected to ground potential, wherein the second terminal of the first splitting resistance is connected to the control unit for providing the partial voltage; a control apparatus which is configured to use the reference voltage (U ref) and the partial voltage to provide a regulating signal, wherein the control apparatus has an operational amplifier having an inverting input, a non-inverting input and an output, wherein the inverting input of the operational amplifier is connected to the reference device for receiving the reference voltage (U ref), wherein the non-inverting input of the operational amplifier is connected to the splitting device for receiving the partial voltage and with the modifying apparatus for modifying the partial voltage, wherein the output of the operational amplifier is connected to the regulating apparatus for providing the regulating signal; a regulating apparatus, which is connected between the input terminal and the output terminal, wherein the regulating apparatus is configured to use the input voltage (U in) and the regulating signal provide the output voltage (U out); and a modifying apparatus, which is configured to use the test voltage to modify a value of the partial voltage, wherein the modifying apparatus has a switch and an electrical modification resistance, wherein the switch and the modification resistance are connected to one another in series between ground potential and the non-inverting input of the operational amplifier of the control apparatus, wherein a control terminal of the switch is connected to the test terminal. an input terminal for applying an electrical input voltage (U in), a test terminal for applying an electrical test voltage and an output terminal for providing an electrical output voltage (U out) for supplying the control unit; a reference device which is configured to use the input voltage (U in)to provide a reference voltage (U out); a splitting device which is configured to use the output voltage (U out) to provide a partial voltage, wherein the splitting device has a first electrical splitting resistance and a second electrical splitting resistance, wherein a first terminal of the first splitting resistance is connected to the output terminal, wherein a second terminal of the first splitting resistance is connected to a first terminal of the second splitting resistance, wherein a second terminal of the second splitting resistance is connected to ground potential, wherein the second terminal of the first splitting resistance is connected to the control unit for providing the partial voltage; a control apparatus which is configured to use the reference voltage (U ref) and the partial voltage to provide a regulating signal, wherein the control apparatus has an operational amplifier having an inverting input, a non-inverting input and an output, wherein the inverting input of the operational amplifier is connected to the reference device for receiving the reference voltage (U ref), wherein the non-inverting input of the operational amplifier is connected to the splitting device for receiving the partial voltage and with the modifying apparatus for modifying the partial voltage, wherein the output of the operational amplifier is connected to the regulating apparatus for providing the regulating signal; a regulating apparatus, which is connected between the input terminal and the output terminal, wherein the regulating apparatus is configured to use the input voltage (U in) and the regulating signal provide the output voltage (U out); and a modifying apparatus, which is configured to use the test voltage to modify a value of the partial voltage, wherein the modifying apparatus has a switch and an electrical modification resistance, wherein the switch and the modification resistance are connected to one another in series between ground potential and the non-inverting input of the operational amplifier of the control apparatus, wherein a control terminal of the switch is connected to the test terminal.