what sensor is this??

[J. Kennedy]

4.0 intake manifold, just to the passenger side of the T-stat housing. One-wire. What is it?

I ask cuz I found a thread asking about bad mileage. It said if you get crappy mileage (yep), check your T-stat (OK), and your coolant temp sensor.

Ran out to NAPA and bought a $18 "Coolant Temp Sensor". It replaced the 2 wire unit to the drivers side of the T-stat. The old one was metal, the new one is plastic.

While changing it I noticed the 1-wire sensor. What is it?

 

[Lloyd10977]

According to my Haynes manual, the item you described on the OHV engine is the WATER TEMPERATURE SENDER. The ENGINE COOLANT TEMPERATURE SENSOR (which you replaced and has 2 wires) sends its signal to the PCM, while the WATER TEMPERATURE SENDER sends its signal to the dashboard.