2.3L Coolant Sending Unit or Coolant Sensor

Before going to the trouble of removing the coolant sender from the 2.3L Ford engine block and testing it, perform the tests presented to ensure that it is the sender malfunctioning, and not another part of the circuit.  Unit is on Left side rear of engine, under cylinder head, near oil filter (see the diagrams).

Steps:

1. Verify that engine to body grounding strap is good and not corroded.  Bad or missing strap will cause high temp readings.
2. Check wiring to sensor for damage and corrosion.
3. Verify full coolant level.
4. Check sensor: 73 ohms cold, 10 ohms hot. (+/- 2 ohms)

How to removal and install.

1. Disconnect the negative battery cable.

2. Remove the radiator cap to relieve any system pressure.

3. Disconnect the wiring at the coolant sender.

4. Remove the coolant temperature sender from the engine.

5. Coat the threads on the sender with Teflon® tape or electrically conductive sealer, then install the sender. 6. Tighten the sender to 107-143 inch lbs. (12-16 Nm) NOT ft/lbs.

7. Attach the wiring to the coolant sending unit and connect the negative battery cable.

8. If necessary, add antifreeze to replace any lost coolant, then install the radiator cap.

Sensor Pics (could be either)

2.3 L coolant sensor 

2.3L coolant sending unit

You can also check the unit in a pan of water, if removed from the truck.