Page 1985 of 3342
B2M1058
C: DTC P0102
—MASS AIR FLOW SENSOR CIRCUIT LOW
INPUT—
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
Erroneous idling
Engine stalls.
Poor driving performance
WIRING DIAGRAM:
B2M1057
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.
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Page 1986 of 3342

OBD0145A
10C1CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
the OBD-II general scan tool switch to ON.
4) Start engine.
B2M0481
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.
Subaru Select Monitor
Designate mode using function key.
Function mode: F06
F06: Mass air flow and voltage input from mass air flow
sensor are shown on display at the same time.
: Is the value equal to or more than 1.3 g/sec
or 0.3 V and equal to or less than 250 g/sec
or 5.0 V in function mode F06?
Probable cause: Poor connect of connectors, circuit and
grounding line.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. A temporary poor
contact of the connector or harness may be the
cause. Repair harness or connector in the mass
air flow sensor.
NOTE:
In this case, repair the following:
Open or ground short circuit in harness between mass
air flow sensor and ECM connector
Poor contact in mass air flow sensor or ECM connector
: Go to step10C2.
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Page 1987 of 3342

B2M0532A
10C2CHECK INPUT SIGNAL FOR ECM.
(USING VOLTAGE METER AND SUBARU
SELECT MONITOR.)
Measure voltage between ECM connector and chassis
ground while engine is idling.
: Connector & terminal
(B84) No. 5 (+)—Chassis ground ( ):
Is the voltage less than 0.3 V?
: Go to step10C3.
: Go to next.
B2M0481
: Does the voltage change more than 0.3 V by
shaking harness and connector of ECM
while monitoring the value with Subaru
select monitor?
: Repair poor contact in ECM connector.
: Contact with SOA service.
NOTE:
Inspection by DTM is required, because probable cause is
deterioration of multiple parts.
B2M0645A
10C3CHECK POWER SUPPLY TO MASS AIR
FLOW SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from mass air flow sensor.
3) Turn ignition switch to ON.
4) Measure voltage between mass air flow sensor connec-
tor and engine ground.
: Connector & terminal
(B3) No. 1 (+)—Engine ground ( ):
Is the voltage more than 10 V?
: Go to step10C4.
: Repair open circuit in harness between main relay
and mass air flow sensor connector.
136
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Page 1988 of 3342

B2M1059A
10C4CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM and
mass air flow sensor connector.
: Connector & terminal
(B84) No. 5—(B3) No. 4:
Is the resistance less than 1Ω?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:
Open circuit in harness between ECM and mass air flow
sensor connector
Poor contact in mass air flow sensor connector
Poor contact in ECM connector
: Connector & terminal
(B84) No. 53—(B3) No. 3:
Is the resistance less than 1Ω?
: Go to step10C5.
: Repair harness and connector.
NOTE:
In this case, repair the following:
Open circuit in harness between ECM and mass air flow
sensor connector
Poor contact in mass air flow sensor connector
Poor contact in ECM connector
B2M1060A
10C5CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
Measure resistance of harness between ECM connector
and chassis ground.
: Connector & terminal
(B84) No. 5—Chassis ground:
Is the resistance more than 1 MΩ?
: Replace mass air flow sensor.
: Repair ground short circuit in harness between
ECM and mass air flow sensor connector.
137
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles
Page 1989 of 3342
B2M1061
D: DTC P0103
—MASS AIR FLOW SENSOR CIRCUIT HIGH
INPUT—
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
Erroneous idling
Engine stalls.
Poor driving performance
WIRING DIAGRAM:
B2M1057
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.
138
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles
Page 1990 of 3342
OBD0145A
10D1CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
the OBD-II general scan tool switch to ON.
4) Start engine.
B2M0481
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.
Subaru Select Monitor
Designate mode using function key.
Function mode: F06
F06: Mass air flow and voltage input from mass air flow
sensor are shown on display at the same time.
: Is the value equal to or more than 1.3 g/sec
or 0.3 V and equal to or less than 250 g/sec
or 5.0 V in function mode F06?
Probable cause: Poor connect of connectors, circuit and
grounding line.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time.
: Go to step10D2.
139
2-7ON-BOARD DIAGNOSTICS II SYSTEM
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Page 1991 of 3342
B2M0481
10D2CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn ignition switch to OFF and Subaru Select Monitor
or the OBD-II general scan tool switch to OFF.
2) Disconnect connector from mass air flow sensor.
3) Turn ignition switch to ON and Subaru Select Monitor or
the OBD-II general scan tool switch to ON.
4) Read data on Subaru select monitor or OBD-II general
scan tool.
Subaru Select Monitor
Designate mode using function key.
Function mode: F06
: Is the value more than 250 g/sec or5Vin
function mode F06?
: Repair battery short circuit in harness between
mass air flow sensor and ECM connector. After
repair, replace ECM.
: Replace mass air flow sensor.
OBD-II general scan tool
For detailed operation procedures, refer to OBD-II General
Scan Tool Instruction Manual.
140
2-7ON-BOARD DIAGNOSTICS II SYSTEM
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Page 1992 of 3342
B2M1062
E: DTC P0106
—PRESSURE SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM—
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
WIRING DIAGRAM:
B2M1308
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.
141
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles