Air By-Pass Valve

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Check that the air by-pass valve has no deformation, cracks or other damages.
Connect the Mighty Vac to the nipple (A) of the air by-pass valve.

Fig 1: Identifying Air By-Pass Valve Nipple
Courtesy of SUBARU OF AMERICA, INC.
Using the Mighty Vac, generate the negative pressure to -93.3 kPa (-0.95 kgf/cm² , -13.5 psi). Check that the Mighty Vac gauge needle holds 10 seconds without falling by -92.6 kPa (-0.94 kgf/cm² , -13.4 psi).
Set a dial gauge to the end of valve rod of the air by-pass valve.

Fig 2: Setting Dial Gauge To End Of Valve Rod Of Air By-Pass Valve
Courtesy of SUBARU OF AMERICA, INC.
Using the Mighty Vac, generate the negative pressure, and check the pressure when dial gauge needle (valve stroke) shows 0.5 mm (0.02 in). If it is not within the standard, replace the air by-pass valve.
Opening pressure (valve stroke 0.5 mm (0.02 in)):

Standard

-53.3 - -61.3 kPa

(-0.54 - -0.63 kgf/cm ² , -7.73 - -8.89 psi)
Generate the additional negative pressure from 5), and check the pressure when dial gauge needle (valve stroke) shows 7.5 mm (0.3 in). If it is not within the standard, replace the air by-pass valve.
Full open pressure (valve stroke 7.5 mm (0.3 in)):

Standard

-93.4 - -108 kPa

(-0.95 - -1.10 kgf/cm ² , -13.5 - -15.7 psi)