A method of managing the degraded modes of a system for the automatic starting/stopping of a heat engine of a vehicle, whereby the system receives information supplied by measurement and detection sensors and by a bus for the communication of vehicle operating data. The method comprises the following steps consisting in verifying the presence and validity of the information supplied by the sensors and, in the event of a negative result, defining a first degraded mode in which any stopping phase of the automatic start/stop mode is forbidden until an end-of-restriction condition has been fulfilled, and, in the even of a positive result, testing the communication with the data communication bus and, in the event of a negative result, defining a second degraded mode in which the automatic start/stop mode is inhibited until an end-of-inhibition condition has been fulfilled.