Resistance inspection

1. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
2. Remove the plug hole plate. (See PLUG HOLE PLATE REMOVAL/INSTALLATION .)
3. Drain the engine coolant. (See ENGINE COOLANT REPLACEMENT .)
4. Pull out the evaporative hose No. 1 from the catch tank and set it aside. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
5. Remove the clip from the bracket and loosen the wiring harness. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
6. Set the wiring harness aside. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
7. Disconnect the ECT sensor No. 1 connector.
8. Remove the ECT sensor No. 1. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
9. Place the ECT sensor No. 1 in water with a thermometer, and heat the water gradually.
   Fig 1: Inspecting Engine Coolant Temperature Sensor

   Courtesy of MAZDA MOTORS CORP.
10. 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 .)

Specification (Reference) 

Fig 2: ECT Sensor No. 2 Resistance Graph

Courtesy of MAZDA MOTORS CORP.