A diagnostic system for a DC-DC voltage converter is provided. A first temperature sensor generates a first temperature signal associated with a buck mode integrated circuit. A first analog multiplexer outputs the first temperature signal to a first analog-to-digital converter which generates a first temperature value. A second temperature sensor generates a second temperature signal associated with a boost mode integrated circuit. A second analog multiplexer outputs the second temperature signal to a second analog-to-digital converter which generates a second temperature value. A microcontroller generates control signals to command first and second bi-directional switches in the DC-DC voltage converter to each transition to an open operational state if the first temperature value is greater than a first threshold temperature value.