Lexus 12261-20040 Ventilation Hose

Fresh air is drawn from the air filter housing through hoses into the engine's crankcase. This fresh air mixes with blow-by gases and exits through the PCV valve into the intake manifold. During conditions of high intake manifold vacuum, such as idle and part-throttle, blow-by gases flow through the PCV valve and crankcase ventilation hose into the intake manifold. Meanwhile, fresh air is drawn from the air intake duct through the fresh air inlet hose into the crankcase.

Checking and potentially replacing PCV components, such as the PCV valve and hoses, is recommended during routine maintenance tasks like oil filter changes, air filter replacements, fuel filter replacements, or spark plug changes. This helps ensure the continued effectiveness of the PCV system.