Replace with a 10k ohm thermistor (not a resistor). Thermistor is a temperature dependant resistor that changes resistance value with temperature change. If you look up NTC Thermistor 10k any electronics component suppliers will have them and the should only cost a few dollars at most ans in some countries just a few cents. In my case the thermistor was missing just the two wires where there. So I solders the replacement back on. I checked it against the external air temp that was 29C at the time and the ODB2 showed that the Thermistor was reading 29.3C. I then held the thermistor for a few minutes and checked the ODB2 reading and it showed 37.6 so the ECU was interpreting the thermistor reading correctly.
