Lexus 12204-20040 Ventilation Valve Sub-Assembly

The Positive Crankcase Ventilation (PCV) system reduces hydrocarbon emissions by cutting crankcase vapors. It does this by circulating fresh air from the cleaner to the crankcase, mixing it with blow-by gases. These gases are moved through a PCV valve and taken back to the intake. The PCV has the PCV valve, a blow-by filter, and vacuum hoses connecting them to the engine. The PCV valve is intended to block flow during high-intake vacuum conditions to maintain consistent quality. If there is anything unusual, the system allows blow-by gases to go back into the air cleaner from the vent tube.

The PCV valve and hose is located in the valve cover. To check it, disconnect the hose and pull the PCV valve from the cover, then reconnect the hose. With the engine idling at normal operating temperature, place your finger over the valve opening. If there's no vacuum at the valve, check for a plugged hose or valve and replace any plugged or deteriorated hoses. After this, turn off the engine and remove the PCV valve from the hose. Blow through the valve from the valve cover (cylinder head) end. If air will not pass through the valve in this direction, replace it with a new one. To check the PCV valve, first attach a clean section of hose to the cylinder head side of the valve and blow through it - air should pass through easily - then blow through the opposite side of the valve and verify that air doesn't pass through it. When purchasing a replacement PCV valve, make sure it's for your particular vehicle and engine size. Compare the old valve with the new one to make sure they're the same.

When purchasing a replacement PCV valve, make sure it's for your particular vehicle and engine size. Compare the old valve with the new one to ensure they're the same.

On 1AR-FE models, the intake manifold needs to be removed to access the PCV valve.