Hi Jacob - generally the car electrics operate at 12 volts but the temp sensor circuit work at around 10 volts via a regulator which is usually fitted to the dash readout panel. This is done to smooth out the voltage changes which can range from 11 to 14 volts. On some cars the regulator also feeds the fuel guage system.
arh.... so if the multimeter detects no voltage to the sensor than this more-a-less indicates that there is either a fault with the voltage stabaliser, or there is a fault with the clocks receiving the initial 12 volts. (doubt the latter though as everything else works, and the self diagnostics check out o.k aswell)
Im putting my money on the clocks to be honest, but I will conduct the voltage test. Can you confirm my theory on testing the voltage is correct, just disconnecting the connector, connecting one of the multimeter probes to the gauge wire and then the other to the negative of the battery or similar?