This is a EGR valve temperature sensor video. This video describe how the EGR valve temperature sensor works. The EGR gasses temperature sensor works like the coolant temperature sensor. The sensor uses the thermistor that has negative temperature Coefficient. That means the resistance decreases with increasing temperature. Here is the tutorial video:

The operation of the EGR temperature sensor is very simple. The sensor is placed straight in the path of the EGR flow. The EGR gasses that flow will heat the sensor, make the resistance of the sensor drop.