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 MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 67 (ENGINE CONTROLS - SELF-DIAGNOSTICS)SYSTEM TESTSPOSITIVE CRANKCASE VENTILATION SYSTEM
2008 Mazda 6 s Sport, 4D Hatchback, Standard
Positive Crankcase Ventilation System
2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION Positive Crankcase Ventilation System
WARNING: This page is about a different car, the 2003 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
- Stuck PCV Valve Check - Turn ignition off. Verify PCV valve maintenance schedule has been followed. Verify proper PCV valve part number. Verify PCV valve is clean. Shake PCV valve. If PCV valve rattles when shaken, reinstall PCV valve and go to next step. If PCV valve does not rattle when shaken, replace PCV valve.
- PCV System Check - Start engine and bring to normal operating temperature. Disconnect closure (fresh air) hose from remote air cleaner or air inlet tube (tube connecting Mass Airflow/Intake Air Temperature (MAF/IAT) sensor and throttle body). Place a stiff piece of paper over the hose end. Wait one minute. If vacuum holds paper in place, PCV system is okay. Reconnect hose. Refer to SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES article. If vacuum does not hold paper in place, PCV system is leaking/plugged or EVAP system is leaking. Go to next step.
- Evaporative Emission System Check - If EVAP emission hose is not connected to PCV hose, perform no further action. Otherwise, disconnect EVAP emission hose at connection to PCV hose (if equipped). Cap connector. Start engine. Again, place a piece of stiff paper over closure (fresh air) hose end. Wait one minute. If vacuum holds paper in place, PCV system is okay. Go to step 4 under DTC P0455 or P1443 under DIAGNOSTIC PROCEDURES under DIAGNOSTIC TESTS. If vacuum does not hold paper in place, check for vacuum leaks/obstructions in PCV system (oil cap, PCV valve, hoses, cut grommets or valve cover bolt torque/gasket leaks). Repair as necessary.
NOTE:
This test is intended to diagnose only the PCV valve and related vacuum lines.
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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.