The invention relates to a method for the external monitoring of a converter (10), the converter (10) being controlled by means of a first electronic control system (12) and the method being implemented by means of a second electronic control system (14) which is independent from the first electronic control system (12). Said method comprises detection (S1) of a current (I) received by the converter (10) and a voltage (U) received by the converter (10) by means of a current/voltage sensor device (16) which is independent from the first electronic control system (12). The invention also relates to a device for monitoring a converter (10), to a computer program product, to a machine-readable storage medium, to a drive train of a motor vehicle, and to a corresponding motor vehicle.