Coolant Temperature Sensor & Air Temperature Sensor

To test the coolant temperature sensor, I had to put it in a bowl of water on a stove and measure its resistance as the temperature of the water goes up. If there was no continuity then that meant that the sensor is not working. The coolant temperature sensor senses engine temperature. If temp. is too high, ECU tells injectors to slow down flow. If temp. is too low. injectors speed up. Air temperature sensor is similar. To test this one, I had to heat it up with a heat gun and record its continuity as the temperature rises.Air gets denser as its temperature increases so cold air would mean more fuel needed to be injected.