There are many ways to measure temperature though i'm not sure what Holden uses in its vehicles.
One method is to use a thermistor which is simply a resistor whose resitance value changes with temperature. They are cheap to buy but you need to know the reststance and temperature charactaristics to buy the correct one. If you're lucky the workshop manual may have a resistance verses temperature chart for this sensor. Alternatively, their may be some markings on the old sensor itself which you may be able to use to google the correct component. Once you get the correct thermistor, simply cut the old one off and solder the new on onto the existing harness.
Otherwise just buy the appropriate part, maybe
this expensive part though not sure if its the correct part