1996 SUBARU LEGACY display

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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2-7ON-BOARD DIAGNOSTICS II SYSTEM
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.




172
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

10M1
CHECK DTC P0130 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0130?
: Go to step10M2.
: Go to step10M3.
10M2
CHECK FAILURE CAUSE OF P0130.
Perform the step 1 of DTC P0130.
: Is the failure cause of P0130 in the fuel sys-
tem?
: Check fuel system.
NOTE:
In this case, it is not necessary to inspect DTC P0136.
: Go to step10M3.
OBD0145A
10M3
CHECK REAR OXYGEN SENSOR DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or OBD-II general scan
tool to data link connector.
3) Start the engine, and turn Subaru Select Monitor or
OBD-II general scan tool switch to ON.
4) Warm-up the engine until engine coolant temperature is
above 70°C (160°F), and keep the engine speed at 2,000
rpm to 3,000 rpm for two minutes.
B2M0488
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F13

F13: Rear oxygen sensor output signal is indicated.
: Does the value fluctuate in function mode
F13?
: Go to step10M5.
: Go to next.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0229
N: DTC P0139
—REAR OXYGEN SENSOR CIRCUIT SLOW
RESPONSE (RO2
—R)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
10N1Check DTC P0136 on display.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:

LHD Model
B2M0760
177
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0789
10N1
CHECK DTC P0136 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0136?
: Inspect DTC P0136 using“10. Diagnostics Chart
with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0139.
: Replace rear oxygen sensor.
178
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0232
O: DTC P0141
—REAR OXYGEN SENSOR HEATER
CIRCUIT MALFUNCTION (RO2H)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
10O1Check DTC P0135 on display.
10O2Connect Subaru Select Monitor or the OBD-II
general scan tool, and read data.
10O3Check output signal from ECM. (Using voltage
meter.)
10O4Check power supply to rear oxygen sensor.
10O5Check rear oxygen sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.





179
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0790
10O1
CHECK DTC P0135 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0141 and
P0135 at the same time?
: Go to next step 1).
: Go to step10O2.
181
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0145A
10P5
CHECK MASS AIR FLOW SENSOR.
1) Turn ignition switch to OFF.
2) Connect the Subaru Select Monitor or the OBD-II gen-
eral scan tool to data link connector.
3) Start the engine and warm-up engine until coolant tem-
perature is greater than 60°C (140°F).
4) Place the selector lever in“N”or“P”position.
5) Turn A/C switch to OFF.
6) Turn all accessory switches to OFF.
B2M0481
7) 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.
: Is the voltage in function mode F06 within
the specifications shown in the following
table?
Model Engine speed Specified value
2200 ccIdling 1.7—3.3 (g/sec)
2,500 rpm 7.1—14.2 (g/sec)
2500 ccIdling 2.2—4.2 (g/sec)
2,500 rpm 8.6—14.5 (g/sec)
: Contact with SOA service.
NOTE:
Inspection by DTM is required, because probable cause is
deterioration of multiple parts.
: Replace mass air flow sensor.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code