ECT Sensor No. 1 Inspection

Remove the battery cover. (See BATTERY REMOVAL/INSTALLATION [L3 WITH TC] ).
Disconnect the negative battery cable.
Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS ).
Remove the battery and battery tray. (See BATTERY REMOVAL/INSTALLATION [L3 WITH TC] ).
Disconnect the ECT sensor No. 1 connector.
Remove the ECT sensor No. 1. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION ).
Place the ECT sensor No. 1 in water with a thermometer, and heat the water gradually.

Measure the resistance between the ECT sensor No. 1 terminals A and B using an ohmmeter.

ECT SENSOR NO. 1 SPECIFICATION

ECT (°C {°F})	Resistance (kilohms)
20{68}	Approx. 37.3
80{176}	Approx. 3.84

Fig 1: Identifying ECT Sensor No. 1 Connector Terminals

Courtesy of MAZDA MOTORS CORP.