A method for determining an opening behavior of a combustion engine fuel injector having a coil drive includes: applying to a coil of the coil drive an electrical test excitation that is weaker than an electrical standard excitation applied to the coil during normal operation of the engine, such that an opening position of the fuel injector is achieved at a point at which the coil drive is not in magnetic saturation; measuring the chronological progression of an electrical variable of the coil; determining a first point in time at which the fuel injector reaches its opening position under the influence of the electrical test excitation, based on the measured chronological progression of the electrical variable, and determining a second point in time at which the fuel injector would reach its opening position under the influence of the electrical standard excitation, based on the determined first point in time.