Short-circuit fault-detecting lighting device for a motor vehicle headlight, comprising - a voltage input (SE) and a connector (ME) for connection to earth potential, - a power line (LS) which is supplied via the voltage input (SE) and comprises a number of light sources to be monitored, this number being at least two, the light sources being set up to emit the light of the lighting device and the light sources being connected in series with one another within the power line (LS), wherein the lighting device further comprises - has an auxiliary line (HS) with transistors arranged therein and connected in series with one another, one of the transistors being assigned to each light source of the power line (LS), and thus a monitoring pair (P1, P2, P3, P4), consisting of a light source to be monitored and a transistor assigned for monitoring, each transistor being coupled to the cathode and anode of the light source in such a way that the voltage dropping across the light source during normal operation is used for this purpose, the transistor is switched through, and in the event of a short circuit of the light source , the voltage dip caused by the short circuit leads to a blocking of the transistor and thus of the auxiliary line (HS), the short-circuit fault-detecting lighting device furthermore having a fault detection device which is coupled to the auxiliary line (HS) and is set up to output a fault signal (SF) or to trigger a fault routine (FR) in the event of the auxiliary line being blocked, characterized in that the fault detection device is set up for carrying out a fault routine (FR) in which the operation of the light sources is switched off automatically in the event of a fault being detected, it being provided for this purpose that both the power line (LS) and the auxiliary line (HS) extend between the voltage input (SE) and the connector (ME) and the fault detection device is designed as a main switch which is arranged in series with the power line (LS) and is coupled to the auxiliary line (HS) in such a way that the main switch conducts electrically when the auxiliary line (HS) is switched through and blocks electrically when the auxiliary line (HS) is blocked. - a voltage input (SE) and a connector (ME) for connection to earth potential, - a power line (LS) which is supplied via the voltage input (SE) and comprises a number of light sources to be monitored, this number being at least two, the light sources being set up to emit the light of the lighting device and the light sources being connected in series with one another within the power line (LS), wherein the lighting device further comprises - has an auxiliary line (HS) with transistors arranged therein and connected in series with one another, one of the transistors being assigned to each light source of the power line (LS), and thus a monitoring pair (P1, P2, P3, P4), consisting of a light source to be monitored and a transistor assigned for monitoring, each transistor being coupled to the cathode and anode of the light source in such a way that the voltage dropping across the light source during normal operation is used for this purpose, the transistor is switched through, and in the event of a short circuit of the light source , the voltage dip caused by the short circuit leads to a blocking of the transistor and thus of the auxiliary line (HS), the short-circuit fault-detecting lighting device furthermore having a fault detection device which is coupled to the auxiliary line (HS) and is set up to output a fault signal (SF) or to trigger a fault routine (FR) in the event of the auxiliary line being blocked, <EOS>