Method and system for operating an electric machine controlled by an inverter in a motor vehicle when an error occurs

The method involves storing electrical energy generated by electrical machine (1) in energy store (5) during generator mode. The charge state of energy store is compared with preset lower threshold so as to detect error state. The electrical machine is switched to a free-running mode from generator mode by opening controllable switching elements (3a-3f) of inverter (2), when charge state of energy store is lower than preset lower threshold. A message is issued to driver so as to set lower gear ratio, when error state is detected. An independent claim is included for system for operating electric machine used in motor vehicle.