Check Mass Air Flow Sensor Unit

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.

Connect battery positive terminal to terminal No. 3 and battery ground terminal to terminal No. 4, and circuit tester positive terminal to terminal No. 5 and circuit tester negative terminal to terminal No. 4.

Fig 1: Checking Mass Air Flow Sensor Unit
Courtesy of SUBARU OF AMERICA, INC.
Check that the voltage changes when air is blown to the mass air flow sensor unit from arrow direction.

Fig 2: Locating Mass Air Flow Sensor Unit Air Blown Direction
Courtesy of SUBARU OF AMERICA, INC.