Check The Mass Air Flow Sensor Unit

1. Connect the battery positive terminal to terminal No. 3 and the battery ground terminal to terminal No. 4, the circuit tester positive terminal to terminal No. 5 and the circuit tester ground terminal to terminal No. 4.
   Fig 1: Connecting Battery Positive Terminal 3 And Battery Ground Terminal 4

   Courtesy of SUBARU OF AMERICA, INC.
2. Check the voltage changes when air is blown from the arrow pointing area to the mass air flow sensor unit.

Fig 2: Locating Mass Air Flow Sensor Unit Pointing Area

Courtesy of SUBARU OF AMERICA, INC.