Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSMAZDA20105 SPORT, 2.3 L, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISSYMPTOM TROUBLESHOOTING [L3] - ENGINENO. 18 COOLING SYSTEM CONCERNS-RUNS COLDDIAGNOSTIC PROCEDURE

2010 Mazda 5 Sport, 2.3 L, Standard

Diagnostic procedure

2010 Mazda 5 Sport, 2.3 L, StandardSECTION Diagnostic procedure

DIAGNOSTIC PROCEDURE CHART

STEP	INSPECTION	RESULTS	ACTION
1	Is 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 .)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Inspect cooling fan control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION .) Does the cooling fan control system function properly?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning part.
4	Cool down the engine. Remove the thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION .) (See THERMOSTAT INSPECTION .) Is thermostat normal?	Yes	Inspect the water temperature gauge on the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION .) If not normal, replace the instrument cluster. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION .) If normal, inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .)
4		No	Replace the thermostat.
5	Verify test results. If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX .) If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, replace PCM. (See PCM REMOVAL/INSTALLATION .)

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.