Resistance Inspection

Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
Drain the engine coolant. (See ENGINE COOLANT REPLACEMENT .)
Disconnect the ECT sensor No. 1 connector.
Remove the ECT sensor No. 1 using the SST. (See 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 No. 1 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. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)

ECT SPECIFICATION (REFERENCE)

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

Fig 2: Engine Coolant Temperature And Resistance Graph

Courtesy of MAZDA MOTORS CORP.