DTC P0108: Manifold Absolute Pressure/Barometric Pressure Sensor Circuit High: Notes

DTC detecting condition: 

Immediately at fault recognition

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CURRENT DATA. 
   1. Start the engine.
   2. Read the value of «Mani. Absolute Pressure» using the Subaru Select Monitor or a general scan tool.
      NOTE:

      • Subaru Select Monitor

        For detailed operation procedures, refer to "Current Data Display For Engine". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>SUBARU SELECT MONITOR

      • General scan tool

        For detailed operation procedures, refer to the general scan tool operation manual.

   Is the value of «Mani. Absolute Pressure» 119.5 kPa (896.5 mmHg, 35.29 inHg) or more?

   Yes:  Go to  2

   No:  Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK HARNESS BETWEEN ECM AND MANIFOLD ABSOLUTE PRESSURE SENSOR CONNECTOR. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from manifold absolute pressure sensor.
   3. Start the engine.
   4. Read the value of «Mani. Absolute Pressure» using the Subaru Select Monitor or a general scan tool.
      NOTE:

      • Subaru Select Monitor

        For detailed operation procedures, refer to "Current Data Display For Engine". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>SUBARU SELECT MONITOR

      • General scan tool

        For detailed operation procedures, refer to the general scan tool operation manual.

   Is the value of «Mani. Absolute Pressure» 119.5 kPa (896.5 mmHg, 35.29 inHg) or more?

   Yes:  Repair the short circuit to power in harness between ECM connector and manifold absolute pressure sensor connector.

   No:  Go to  3

3. CHECK HARNESS BETWEEN ECM AND MANIFOLD ABSOLUTE PRESSURE SENSOR CONNECTOR. 
   1. Turn the ignition switch to OFF.
   2. Measure the resistance of harness between manifold absolute pressure sensor connector and engine ground.

      Connector & terminal 

      (E21) No. 1 - Engine ground:

   Is the resistance less than 5 Ω?

   Yes:  Go to  4

   No:  Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit of harness between ECM connector and manifold absolute pressure sensor connector
   • Poor contact of ECM connector
4. CHECK FOR POOR CONTACT. 

   Check for poor contact of manifold absolute pressure sensor connector.

   Is there poor contact of manifold absolute pressure sensor connector?

   Yes:  Repair the poor contact of manifold absolute pressure sensor connector.

   No:  Replace the manifold absolute pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>MANIFOLD ABSOLUTE PRESSURE SENSOR