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: Placing ECT Sensor No. 1 In Water With Thermometer
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 ).

RESISTANCE SPECIFICATION

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

Fig 2: Engine Coolant Temperature Sensor Resistance Graph

Courtesy of MAZDA MOTORS CORP.