I'm having to think on this one too!

The coolant sensor work on a resistance value to the ECU.

The more resistance the colder the ECU thinks the engine temperature is.

A disconnected wire means a open circuit = A lot of resistance means no flow of signal to and from the sensor.

Interpreted inside the ECU as a engine very cold or on the newer cars an engine fault code and possible light.

The statement will read "engine coolant sensor" in the a translator's manual.

Like in other languages the "translations" loses the concept of complete thought and a conversation. The reason for your "WTF" statement.

You have a problem of a wire to the ECU from the sensor is shorting to a ground, the wires or chassis. A short circuit is closed circuit with "0" resistance. It should have approx. 350 ohms.

The "0" sent to the Ecu and it thinks a hot to very hot engine and leans the fuel.

If other things are working correctly like the 0-2 sensor, the battle begins. The ECU has a conflict of its program and at about 15 to 28 times a second samples the readings and tries to adjust mixture, rpm and timing etc.

This self tuning creates symptoms of the other things we want to think could cause this erratic behavior.

The best thing is to unplug the ECU connector. Find the pin to the coolant sensor and trace it to find the bad/bare spot. Then splice around it. It could be it the connector on the sensor or the two wires (to each other) going home to the ECU.

Happy Hunting and hopefully this helps & Happy Motoring later.