Except Miata
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 Mazda Protege5, 2002 Mazda Protege, 2002 Mazda Millenia, 2002 Mazda MX-5 Miata, and 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
Remove Engine Coolant Temperature (ECT) sensor. Place sensor and a thermometer in a container of water. Connect ohmmeter between ECT sensor terminals. Slowly heat water. Observe resistance reading at specified temperatures. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR SPECIFICATIONS table. If resistance is not as specified, replace ECT sensor.