Check that the manifold absolute pressure sensor has no deformation, cracks or other damages.
Connect dry-cell battery positive terminal to terminal No. 3 and dry-cell battery ground terminal to terminal No. 2, circuit tester positive terminal to terminal No. 1 and the circuit tester ground terminal to terminal No. 2.
NOTE:
- Use new dry-cell batteries.
- Using a circuit tester, check that the initial voltage of each dry-cell battery is 1.6 V or more. And also check that the voltage of three batteries in series is between 4.8 V and 5.2 V.
- For power supply, 5 V DC constant voltage power source can also be used.
Courtesy of SUBARU OF AMERICA, INC.

Check the voltage at a normal atmospheric pressure.

NOTE: The atmospheric pressure at higher altitude is lower than normal. Therefore, the voltage is lower than the standard value.

Terminal No.	Standard
1 (+) and 2 (-)	Approx. 2.0 V (when 25°C (77°F))

Connect the Mighty Vac to the pressure port (A) of manifold absolute pressure sensor.

Courtesy of SUBARU OF AMERICA, INC.
Check the voltage when generating vacuum and positive pressure using Mighty Vac.

CAUTION: Do not apply pressure out of the range of -88 - 200 kPa (-0.9 - 2.04 kgf/cm² , -12.8 - 29.0 psi). Doing so may damage the manifold absolute pressure sensor.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Manifold Absolute Pressure Sensor: Inspection

Use the Manual With the Right Hardware

When to See a Mechanic