Water Temperature Sender Unit Inspection

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS .) (See ENGINE COOLANT REPLACEMENT .)
Remove the ECT sensor.
Place the sensor in water with a thermometer, and heat the water gradually.

Measure the resistance between ECT sensor terminal C and body GND using an ohmmeter.

If not as specified, replace the ECT sensor.

Specification

Water temperature (°C {°F})	Resistance (Ω)
50 {122}	160-230

Fig 1: Identifying ETC Sensor Connector

Courtesy of MAZDA MOTORS CORP.