Resistance Inspection

1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS .) (See ENGINE COOLANT REPLACEMENT )
2. Remove the ECT sensor.
3. Place the ECT sensor in water with a thermometer, and heat the water gradually.
4. Measure the resistance between the ECT sensor terminals using an ohmmeter.
   • If not as specified, replace the ECT sensor.
   • If the ECT sensor is okay, but PID value or PCM terminal 41 voltage are out of specification, perform the CIRCUIT OPEN/SHORT INSPECTION .
   Fig 1: Measuring ECT Sensor Resistance

   Courtesy of MAZDA MOTORS CORP.

Measure the ECT sensor resistance. 

ECT sensor characteristics graph (reference) 

Fig 2: Identifying ECT Sensor Characteristics Graph

Courtesy of MAZDA MOTORS CORP.