SUBARU LEGACY 1996 Service Repair Manual

B2M0487
5) Read data on Subaru Select Monitor or the OBD-II gen-
eral scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F12

F12: Front oxygen sensor max. and min. output signals
are indicated at the same time.
: Is the difference of voltage less than 0.1 V
between the value of max. output and min.
output with function mode F12?
: Go to step10J3.
: Replace front oxygen sensor.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
B2M0545A
10J3CHECK HARNESS BETWEEN FRONT
OXYGEN SENSOR AND ECM CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from front oxygen sensor.
3) Turn ignition switch to ON.
4) Measure voltage between front oxygen sensor harness
connector and engine ground.
: Connector & terminal
(B18) No. 3 (+)—Engine ground ():
Is the voltage more than 0.2 V?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and front oxygen
sensor connector

Poor contact in the ECM connector
: Is there poor contact in front oxygen sensor
connector?
: Repair poor contact in front oxygen sensor con-
nector.
: Replace front oxygen sensor.
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10. Diagnostics Chart with Trouble Code

OBD0209
K: DTC P0133
—FRONT OXYGEN SENSOR CIRCUIT SLOW
RESPONSE (FO2
—R)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
10K1Check DTC P0130 on display.
10K2Check exhaust system.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:

LHD Model
B2M0544

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10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0787
10K1
CHECK DTC P0130 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0130?
: Inspect DTC P0130 using“10. Diagnostics Chart
with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0133.
: Go to step10K2.
10K2
CHECK EXHAUST SYSTEM.
: Is there a fault in exhaust system?
NOTE:
Check the following items.

Loose installation of front portion of exhaust pipe onto
cylinder heads

Loose connection between front exhaust pipe and front
catalytic converter

Damage of exhaust pipe resulting in a hole
: Repair exhaust system.
: Replace front oxygen sensor.
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10. Diagnostics Chart with Trouble Code

OBD0212
L: DTC P0135
—FRONT OXYGEN SENSOR HEATER
CIRCUIT MALFUNCTION (FO2H)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
10L1Check DTC P0141 on display.
10L2Connect Subaru Select Monitor or the OBD-II
general scan tool, and read data.
10L3Check output signal from ECM. (Using voltage
meter.)
10L4Check power supply to front oxygen sensor.
10L5Check front oxygen sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.





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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

LHD Model
B2M0546
167
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0788
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

10L1
CHECK DTC P0141 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0135 and
P0141 at the same time?
: Go to next step 1).
: Go to step10L2.
B2M0547A
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM connec-
tor and chassis ground.
: Connector & terminal
(B84) No. 42—Chassis ground:
Is the resistance less than 5Ω?
: Repair poor contact in ECM connector.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and coupling con-
nector (B22)

Open circuit in harness between coupling connector
(B22) and engine grounding terminal

Poor contact in front oxygen sensor connector

Poor contact in coupling connector (B22)
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10. Diagnostics Chart with Trouble Code

OBD0145A
10L2CONNECT 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
OBD-II general scan tool switch to ON.
4) Start engine.
B2M0497
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F32

F32: Front oxygen sensor heater current is indicated.
: Is the value more than 0.2 A in function
mode F32?
: Repair connector.
NOTE:
In this case, repair the following:

Poor contact in front oxygen sensor connector

Poor contact in ECM connector
: Go to step10L3.

OBD-II scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
B2M0548A
10L3CHECK OUTPUT SIGNAL FROM ECM.
(USING VOLTAGE METER.)
1) Start and idle the engine.
2) Measure voltage between ECM connector and chassis
ground.
: Connector & terminal
(B84) No. 38 (+)—Chassis ground ():
Is the voltage less than 1.0 V?
: Go to step10L4.
: Go to next.
: Does the voltage change less than 1.0 V by
shaking harness and connector of ECM
while monitoring the value with voltage
meter?
: Repair poor contact in ECM connector.
: Go to next step 3).
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10. Diagnostics Chart with Trouble Code

B2M0548A
3) Disconnect connector from front oxygen sensor.
4) Measure voltage between ECM connector and chassis
ground.
: Connector & terminal
(B84) No. 38 (+)—Chassis ground ():
Is the voltage less than 1.0 V?
: Replace ECM.
: Repair short circuit in harness between ECM and
front oxygen sensor connector. After repair short
circuit of harness, replace ECM.
B2M0549A
10L4CHECK POWER SUPPLY TO FRONT
OXYGEN SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from front oxygen sensor.
3) Turn ignition switch to ON.
4) Measure voltage between front oxygen sensor connec-
tor and engine ground.
: Connector & terminal
(B18) No. 2 (+)—Engine ground ():
Is the voltage more than 10 V?
: Go to step10L5.
: Repair power supply line.
NOTE:
In this case, repair the following:

Open circuit in harness between main relay and front
oxygen sensor connector

Poor contact in front oxygen sensor connector

Poor contact in main relay connector
B2M0768
10L5
CHECK FRONT OXYGEN SENSOR.
1) Turn ignition switch to OFF.
2) Measure resistance between front oxygen sensor con-
nector terminals.
: Terminals
No. 1—No. 2:
Is the resistance less than 30Ω?
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between front oxygen sensor
and ECM connector

Poor contact in front oxygen sensor connector

Poor contact in ECM connector
: Replace front oxygen sensor.
171
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10. Diagnostics Chart with Trouble Code

OBD0220
M: DTC P0136
—REAR OXYGEN SENSOR CIRCUIT
MALFUNCTION (RO2
—V)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
10M1Check DTC P0130 on display.
10M2Check failure cause of P0130.
10M3Check rear oxygen sensor data.

10M4Check harness between rear oxygen sensor
and ECM connector.
10M5Check exhaust system.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.




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10. Diagnostics Chart with Trouble Code