Toyota 12204-62010 Ventilation Valve Sub-Assembly

The Positive Crankcase Ventilation (PCV) system reduces hydrocarbon emissions by scavenging crankcase vapors, circulating fresh air from the air cleaner through the crankcase to mix with blow-by gases, which are then rerouted through a PCV valve to the intake manifold. Key components include the PCV valve, fresh air intake, and vacuum hoses connecting these parts to the engine. To maintain idle quality, the PCV valve restricts flow when intake manifold vacuum is high, and in abnormal conditions, it allows excessive blow-by gases to flow back into the air cleaner for combustion. This system can lead to oily residue buildup near the throttle plate, so periodic cleaning is advisable. To check the valve, remove it from the grommet and shake it; a rattling sound indicates it is not clogged. If vacuum is felt when covering the valve opening during idle, the valve is functioning properly; otherwise, it may need replacement or the hose could be plugged. For replacement, pull the valve straight up, inspect the rubber grommet for damage, and clean or replace the hose if necessary. After cleaning, ensure the hose fits snugly, and install a new PCV valve if needed, securing both the valve and hose properly.