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Resistance Inspection

Disconnect the negative battery cable. (Refer to NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
Drain the engine coolant. (Refer to ENGINE COOLANT REPLACEMENT .)
Remove the ECT sensor No. 1. (Refer to ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
Place the ECT sensor No. 1 in water with a thermometer, and heat the water gradually.

Fig 1: Measuring Resistance Between ECT Sensor Terminals
Courtesy of MAZDA MOTORS CORP.

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

If not as specified, replace the ECT sensor No. 1. (Refer to ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)

Specification (Reference)

ECT (°C {°F})	Resistance (Kilohms)
20	Approx. 2.45
80	Approx. 0.318

Fig 2: ECT Sensor Temperature/Resistance Graph

G10969080

Courtesy of MAZDA MOTORS CORP.