Method and apparatus for operating an injection valve

The injection valve (100) comprises a valve needle (20) 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, wherein in the closing position the valve needle (20) rests on a seat. Furthermore the injection valve (100) comprises an electro-magnetic actuator unit (36) being designed to actuate the valve needle (20) . The actuator unit (36) is activated according to a predetermined activation signal with a given activation period (Ti) for effecting a fluid flow out of the injection nozzle. An actuator unit voltage characteristic (Uc) is captured at least over a period of time during which the valve needle (20) could reach the closing position. Depending on the actuator unit voltage characteristic (Uc) a closing time (t_close) is determined representing a time when the valve needle (20) reaches the closing position.