In a bus system with a low-power phase, in which bus members are in a state of reduced current consumption and leave this state when the bus lines (1, 2) are active for a longer period than a predetermined time interval, the function of the bus in the low-power phase is monitored in that a first participant (3) cyclically transmits at least one pulse on the bus during the low-power phase, which pulse has a duration that is shorter than the predetermined time interval and is received and evaluated at least by a second bus member (4) for the purpose of monitoring the bus lines (1, 2).