ECT Sensor No. 1 Inspection

Disconnect the negative battery cable.
Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS .)
Remove the battery. (See BATTERY REMOVAL/INSTALLATION [MZR 1.5] .)
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 using an ohmmeter.

ECT sensor No. 1 specification

ECT SENSOR NO. 1 SPECIFICATION

ECT (°C {°F})	Resistance (kilohms)
20{68}	Approx. 2.45
80{176}	Approx. 0.318

Fig 1: Locating ECT Sensor No. 1

Courtesy of MAZDA MOTORS CORP.