Method for starting an internal combustion engine of a hybrid drive by means of an auxiliary energy source, comprising the steps of: providing an electrical machine and the internal combustion engine which together are intended to generate kinetic energy in the hybrid drive; providing a traction battery for supplying traction energy to the electrical machine, an on-board electrical system comprising a starter for starting the internal combustion engine in the normal mode, wherein the on-board electrical system is fed by an on-board electrical system battery, and a converter control system of a DC/DC converter which is intended to supply power to the on-board electrical system from the traction battery, wherein the on-board electrical system supplies power to the converter control system, characterized by if, in an emergency mode on account of an energy deficit in the on-board electrical system, the energy remaining in the on-board electrical system is not sufficient either to operate the converter control system or to start the internal combustion engine: supplying an external auxiliary amount of energy to the converter control system, this auxiliary amount of energy being lower than the energy deficit for starting the internal combustion engine, in order to at least briefly ensure operation of the converter control system, activating the DC/DC converter by actuation by means of the converter control system and feeding an amount of energy for a starting process, which originates from the traction battery, to the on-board electrical system by the DC/DC converter, this amount of energy, together with the energy remaining in the on-board electrical system, being sufficient to start the internal combustion engine; wherein the method further comprises: starting the internal combustion engine by transmitting rotational energy from the starter. providing an electrical machine and the internal combustion engine which together are intended to generate kinetic energy in the hybrid drive; providing a traction battery for supplying traction energy to the electrical machine, an on-board electrical system comprising a starter for starting the internal combustion engine in the normal mode, wherein the on-board electrical system is fed by an on-board electrical system battery, and a converter control system of a DC/DC converter which is intended to supply power to the on-board electrical system from the traction battery, wherein the on-board electrical system supplies power to the converter control system, characterized by if, in an emergency mode on account of an energy deficit in the on-board electrical system, the energy remaining in the on-board electrical system is not sufficient either to operate the converter control system or to start the internal combustion engine: supplying an external auxiliary amount of energy to the converter control system, this auxiliary amount of energy being lower than the energy deficit for starting the internal combustion engine, in order to at least briefly ensure operation of the converter control system, activating the DC/DC converter by actuation by means of the converter control system and feeding an amount of energy for a starting process, which originates from the traction battery, to the on-board electrical system by the DC/DC converter, this amount of energy, together with the energy remaining in the on-board electrical system, being sufficient to start the internal combustion engine; wherein the method further comprises: starting the internal combustion engine by transmitting rotational energy from the starter.