Method to operate an injection valve, the injection valve comprising - a valve needle preventing a fluid flow out of an injection nozzle in a closing position and enabling the fluid flow of the injection nozzle apart from the closing position, and - an electro-magnetic actuator unit being designed to actuate the valve needle, wherein the method comprises the following steps: - activating the actuator unit according to a predetermined activation signal with a given activation period (Ti) for effecting a fluid flow out of the injection nozzle, - capturing an actuator unit voltage characteristic (Uc) at least over a period of time (T_phase) subsequent to the activation period (Ti), during which period of time (T_phase) the valve needle could reach the closing position, the method being characterized in that it comprises the further steps of: - determining a noise part of the actuator unit voltage characteristic (Uc) by means of determining a smoothed actuator unit voltage characteristic (Us) by at least filtering the actuator unit voltage characteristic (Uc) once with a smoothing filter and subtracting the latter from the actuator unit voltage characteristic (Uc) and - determining a closing time (t_close) representing a time when the valve needle reaches the closing position depending on the noise part of the captured actuator voltage characteristic (Uc), wherein the closing time (t_close) is determined in correlation with a maximum of the noise part. - a valve needle preventing a fluid flow out of an injection nozzle in a closing position and enabling the fluid flow of the injection nozzle apart from the closing position, and - an electro-magnetic actuator unit being designed to actuate the valve needle, - activating the actuator unit according to a predetermined activation signal with a given activation period (Ti) for effecting a fluid flow out of the injection nozzle, - capturing an actuator unit voltage characteristic (Uc) at least over a period of time (T_phase) subsequent to the activation period (Ti), during which period of time (T_phase) the valve needle could reach the closing position, the method being characterized in that it comprises the further steps of: - determining a noise part of the actuator unit voltage characteristic (Uc) by means of determining a smoothed actuator unit voltage characteristic (Us) by at least filtering the actuator unit voltage characteristic (Uc) once with a smoothing filter and subtracting the latter from the actuator unit voltage characteristic (Uc) and - determining a closing time (t_close) representing a time when the valve needle reaches the closing position depending on the noise part of the captured actuator voltage characteristic (Uc), wherein the closing time (t_close) is determined in correlation with a maximum of the noise part. - determining a noise part of the actuator unit voltage characteristic (Uc) by means of determining a smoothed actuator unit voltage characteristic (Us) by at least filtering the actuator unit voltage characteristic (Uc) once with a smoothing filter and subtracting the latter from the actuator unit voltage characteristic (Uc) and - determining a closing time (t_close) representing a time when the valve needle reaches the closing position depending on the noise part of the captured actuator voltage characteristic (Uc), wherein the closing time (t_close) is determined in correlation with a maximum of the noise part.