Modulator Valve
WARNING: This page does not describe the selected car, but rather 234 other vehicles, including the 2018 Mazda 6, 2017 Mazda CX-9, 2014 Mazda MX-5 Miata, 2014 Mazda 6, and 2014 Mazda 5. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect all vacuum and exhaust pipe hoses. Cap fitting going to each EGR control solenoid. Blow into bottom fitting from exhaust pipe end. Apply 7 in. Hg to fitting No. 3 (from ported vacuum source). Vacuum should hold until pressure at bottom fitting is released.