Component Description

WARNING: This page is about a different car, the 2006 Subaru Outback. However, it is still accessible from the selected car via links, so may be relevant.

Pressure control solenoid valve

PCV controls the fuel tank pressure to be equal to the atmospheric air pressure. Normally, the solenoid is set to OFF. And the valve opens and closes mechanically in accordance with the pressure difference between tank and atmospheric air, or tank and canister.

The valve is forcibly opened by setting the solenoid to ON at the time of diagnosis.

Fig 1: Identifying Valve Operation And Air Flow

Valve Operation and Air Flow

In the figure below, divided by the diaphragm, the part above X is charged with atmospheric air pressure, and the part below X is charged with tank pressure. Also, the part above Y is charged with tank pressure, and the part below Y is charged with canister pressure.

If the atmospheric air pressure port is A, tank pressure port is B, and canister pressure port is C, the air flows according to pressure difference from each port as shown in the table below.

Fig 2: Identifying Valve Operation And Air Flow

VALVE OPERATION AND AIR FLOW REFERENCE

Condition of pressure	Flow
A < B (solenoid OFF)	B → C
B < C (solenoid OFF)	C → B
Solenoid ON	B ←→ C

When A < B (solenoid OFF)

Fig 3: Valve Operation And Air Flow When A < B (Solenoid OFF)

When B < C (solenoid OFF)

Fig 4: Valve Operation And Air Flow When B < C (Solenoid OFF)

When Solenoid is ON

Fig 5: Valve Operation And Air Flow When Solenoid Is ON

Drain valve

Drain valve controls the ambient air to be introduced to the canister.

Fig 6: Drain Valve Controls Air Flow Diagram