Engine Coolant Temperature (ECT) Sensor Inspection
WARNING: This page is about a different car, the 2004 Suzuki Aerio and 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
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