Engine Coolant Temperature (ECT) Sensor Inspection
Warm up sender gauge. Thus make sure its resistance is decreased with increase of its temperature. If check result is not as specified, replace sensor.
ECT sensor specification (Temperature: Resistance)
20 °C (68 °F): 2.32 - 2.59 k/ohms
80 °C (176 °F): 310 - 326 k/ohms