EGR Temperature Sensor
WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Sensor is located in EGR passage downstream of EGR valve. EGR temperature sensor operates by sensing temperature increase when exhaust gases pass through EGR passage. If PCM commands EGR solenoid on and EGR temperature sensor does not sense temperature increase for 2 occurrences, DTC will set and MIL will illuminate.