A method is provided for determining the point in time of a predetermined open state (e.g., start or stop time of an opening or closing process) of a fuel injector having a coil drive for an internal combustion engine of a motor vehicle. The method includes applying a first voltage pulse to the magnetic coil drive of the fuel injector, detecting a first temporal progression of the current intensity of a current flowing through the coil drive, applying a second voltage pulse to the magnetic coil drive of the fuel injector, detecting a second temporal progression of the current intensity of the current flowing through the coil drive, determining a differential progression based on the first and second temporal progressions of the current intensity, and determining a point in time at which the differential progression exhibits an extremum, which corresponds with the point in time of the predetermined open state.