SUBARU LEGACY 1995 Service Repair Manual

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

In order to monitor purifying efficiency of the catalyzer,
the rear oxygen sensor sends a signal to the ECM.

Refer to“J: DTC P0130—FRONT OXYGEN SENSOR
CIRCUIT MALFUNCTION—[T11J0]”.
DTC DETECTING CONDITION:

Two consecutive trips with fault
185
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1.Check DTC P0130 on display.
No
Ye s
2.Check failure cause of P0130.
3.Check rear oxygen sensor data.

4.Check harness.
5.Check exhaust system.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. <Ref. to
[T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
OBD0221


186
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD model
B2M0451
187
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1
CHECK DTC P0130 ON DISPLAY.
: Check that Subaru Select Monitor or the
OBD-II general scan tool shows P0130.
: Go to step 2.
: Go to step 3.
2
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. In this case, inspection of
P0136 is not necessary.
: Go to step 3.
OBD0145A
3
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.
OBD0225
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F16

F16: Rear oxygen sensor output signal is indicated.
: Is the indicated data fluctuate?
: Go to step 5.
: Go to next.
: Is the indicated data fixed at 0.3±0.1 V?
: Go to step 4.
: Replace rear oxygen sensor.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
188
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

4
CHECK HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from rear oxygen sensor.
3) Turn ignition switch to ON.
OBD0707A
4) Measure voltage between rear oxygen sensor harness
connector and body.
: Connector & terminal
(T6) No. 4—Body/0.2 V, or more
: Repair harness and connector.
NOTE:
In this case, the following are the possible causes.

1Open circuit of harness between rear oxygen sensor
and ECM connector.

2Poor contact in rear oxygen sensor connector.

3Poor contact in ECM connector.

4Poor contact in rear oxygen sensor connecting harness
connector.
: Replace rear oxygen sensor.
5
CHECK EXHAUST SYSTEM.
: Check the following items.

Looseness of installation portions

Damage (crack, hole etc.) of parts

Looseness and opening of parts between
front oxygen sensor and rear oxygen sen-
sor.
: Repair or replace faulty parts.
: Replace rear oxygen sensor.
189
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0229
N: DTC P0139
—REAR OXYGEN SENSOR CIRCUIT SLOW
RESPONSE (RO2
—R)—
DESCRIPTION:
Refer to“M: DTC P0136—REAR OXYGEN SENSOR
CIRCUIT MALFUNCTION—[T11M0]”.
DTC DETECTING CONDITION:

Two consecutive trips with fault
190
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1.Check DTC P0136 on display.
No
Ye s

Inspect DTC P0136 using“11. Diagnostics Chart
with Trouble Code [T1100]”.

In this case, it is unnecessary to inspect DTC
P0139.
2.Replace rear oxygen sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. <Ref. to
[T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
OBD0221

191
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD model
B2M0451
192
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0232
O: DTC P0141
—REAR OXYGEN SENSOR HEATER
CIRCUIT MALFUNCTION (RO2H)—
DESCRIPTION:
Refer to“M: DTC P0136—REAR OXYGEN SENSOR
CIRCUIT MALFUNCTION—[T11M0]”.
DTC DETECTING CONDITION:

Two consecutive trips with fault
193
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1.Connect Subaru Select Monitor or the OBD-II
general scan tool, and read data.
2.Check output signal from ECM. (Using voltage
meter.)
3.Check power supply to rear oxygen sensor.
4.Check rear oxygen sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. <Ref. to
[T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
OBD0221



194
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code