Except U.S.A. And CANADA
Purpose, function
The check valve maintain the pressure in the fuel tank at constant pressure.
Construction
The check valve is installed to the side of the charcoal canister.

Mainly consists of valve, umbrella, and spring.

Operation
The valve moves in response to the difference in air pressure between the fuel tank side and the atmospheric side, thereby changing the path of airflow.
When the pressure in the fuel tank becomes negative due to fuel consumption or other factors, the path opens, drawing atmospheric air into the fuel tank.
Check Valve Removal/Installation
Emission SystemOil Pump
Outline
The oil pump has a mechanism for feedback control of oil pressure. As a result,
an oil pressure increase of more than the set pressure is suppressed and oil
pump drive resistance is reduced. In addition, because the set pressure can
be changed (oil pressure two-step control) ...
Positive Crankcase Ventilation (PCV) Valve
Purpose, Function
Prevents release of blow-by gas (unburnt gas) into the atmosphere.
The PCV valve is open/closed by the intake manifold vacuum.
Construction
The PCV valve is installed to the oil separator.
The PCV valve consists of a spring and valve.
...
Mass Air Flow (MAF) Sensor Inspection
Visual Inspection
1. Remove the MAF sensor/IAT sensor No.1..
2. Visually inspect the MAF sensor for the following:
Damage, cracks, soiling
Rusted sensor terminal
Bent sensor terminal
If there is any malfunction, repair or replace the MAF sensor/IAT sensor
...