Diagnostic procedure

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

STEP	INSPECTION	RESULTS	ACTION
1	Is the customer complaint "Lack of passenger compartment heat" only?	Yes	Inspect A/C and heater system.
1		No	Go to the next step
2	Does the engine speed continue at fast idle?	Yes	Go to symptom troubleshooting "No. 9 Fast idle/runs on" (See NO. 9 FAST IDLE/RUNS ON [L5] .)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Cool down the engine Remove the thermostat and inspect operation (See THERMOSTAT REMOVAL/INSTALLATION [L5] .) (See THERMOSTAT INSPECTION [L5] .) Is the thermostat normal?	Yes	Go to the next step.
3		No	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [L5] .)
4	Inspect the cooling fan control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L5] ) Does the cooling fan control system function properly?	Yes	Access the ECT PID. Inspect both the ECT PID and the temperature gauge on instrument cluster readings. If the temperature gauge on the instrument cluster indicates a normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. If the temperature gauge on the instrument cluster indicates a cold range but the ECT PID is normal, inspect the temperature gauge and heat gauge unit.
4		No	Repair or replace the malfunctioning part.
5	Verify test results If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [L5] ) If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis If the vehicle is repaired, troubleshooting is completed If the vehicle is not repaired or additional diagnostic information is not available, replace PCM.