The invention relates to a method for operating a hybrid drive device (2) which has an internal combustion engine (3) and an electric machine (4) which can be or is operatively connected to the internal combustion engine (3) and can be operated as a generator, wherein in a normal operating mode a temperature of the electric machine (4) is determined by means of a temperature sensor (14), and operation of the electric machine (4) is permitted only if the temperature is lower than a predefined maximum temperature. There is provision here that in the event of a defect in the temperature sensor (14) an emergency operating mode is carried out in which operation of the electric machine (4) is permitted only with limited power, limited torque and/or over a limited time period. The invention further relates to a hybrid drive device (2).