The disclosure relates to a method for determining a drift in the static fuel flow rate of a piezoelectric injector of a motor vehicle combustion engine. The method relies on fluid-pressure measurements carried out in the injector supply chamber in order to calculate a measured static flow rate value. This value is compared against a nominal static flow rate in order to determine the existence, if any, and amplitude of the drift in the static flow rate. Furthermore, each pressure measurement is carried out when the valve of the injector is closed and the injector is open. In this way, the measured static flow rate calculation is not influenced by pressure-variation effects not relevant to the measurement.