Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

LOW ENGINE COOLANT TEMPERATURE INDICATOR LIGHT/HIGH ENGINE COOLANT TEMPERATURE WARNING LIGHT ILLUMINATES OR FLASHES CONTINUOUSLY (INSTRUMENT CLUSTER) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	PERFORM CAN MALFUNCTION DIAGNOSIS AND DTC INSPECTION Perform the CAN malfunction diagnosis according to the recommendation of FOREWORD [INSTRUMENT CLUSTER]malfunction diagnosis, and if there is no CAN malfunction, perform inspection for DTCs. (See DTC INSPECTION [INSTRUMENT CLUSTER] .) Is the DTC displayed?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [INSTRUMENT CLUSTER] .)
1		No	Go to the next step.
2	VERIFY THE MALFUNCTION SYMPTOM Cool down the engine. When the ignition is switched ON, does the engine coolant temperature warning light illuminate or flash?	Yes	Go to Step 4.
2		No	Go to the next step.
3	VERIFY ILLUMINATION OF LOW ENGINE COOLANT TEMPERATURE INDICATOR LIGHT Start the engine. Monitor the PID ECT using the M-MDS. Verify that the low engine coolant temperature indicator light illuminates when the ECT monitor value is 55 °C {131 °F} or more. Does the low engine coolant temperature indicator light illuminate?	Yes	Go to the next step.
3		No	The system is operating normally.
4	INSPECT ECT SENSOR Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Is the ECT sensor normal?	Yes	Replace the instrument cluster. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION .)
4		No	Replace the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)