Resistance Inspection

1. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
2. Drain the engine coolant. (See ENGINE COOLANT REPLACEMENT .)
3. Remove the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
4. Place the ECT sensor in water with a thermometer, and heat the water gradually.
   Fig 1: Placing ECT Sensor In Water With Thermometer

   Courtesy of MAZDA MOTORS CORP.
5. Measure the resistance between ECT sensor terminals A and B.
   • If not as specified, replace the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)

Specification (Reference) 

Fig 2: ECT Sensor No. 2 Temperature Resistance Graph

Courtesy of MAZDA MOTORS CORP.