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PCV Valve Cleaning Instructions

Model: Hyundai Sonata - Years: 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014
Part: Valve

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The movement of air beneath the cylinders allows oil to be injected more quickly onto the cylinder walls, but it can alter the direction and quantity per side. For better lubrication and thermal efficiency, in sports engines, the sump is kept depressurised (0.4 bar below atmospheric pressure, equal to 1). This depressurisation can be achieved by allowing air to escape, using specific machinery, or if the engine is not multi-cylinder or lacks windows, a special "PCV" (Positive Crankcase Ventilation) valve can be used, which allows air to escape when it becomes too compressed, preventing backflow, thus maintaining lower pressure during piston ascent or through recovery pumps.

The air that exits the valve is contaminated with oil vapours and unburnt fuel, which can clog it, reducing efficiency, so it must be cleaned or replaced as necessary. On the car model in question, the valve is located at the front left of the sump, and you need to disconnect the hose before unscrewing it.


Updated on 18 February 2026 by ScegliAuto


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