89 420SEL Engine Heat Sensor

[blueeagle289]

The heat sensor area on this car involves a vertical tube at the very front top of the engine, with a hole in the back side. A multi-insulated wire appears to fit into this hole to register the engine heat and transmit the reading to the dash heat display unit. Question: What is supposed to be on the end of this wire that goes into the heat tube on the front of the engine; is there some kind of small module that should be there? Mine just has the bare wire and it does not always register ..... Info on this would be appreciate.

Thanks, Ben Carter