Page 1304 of 2453

EN(H6DO)(diag)-143
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:In this case, it is
not necessary to
inspect DTC
P0111.
Go to step 2.
2CHECK ENGINE COOLANT TEMPERA-
TURE.
1) Start the engine and warm-up completely.
2) Measure the engine coolant temperature
using the Subaru Select Monitor or general
scan tool.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
•General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
Is the engine coolant tempera-
ture 75 — 95°C (167 — 203°F)
?
Replace the mass
air flow and intake
air temperature
sensor.
FU(H6DO)-23,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Check DTC P0125
using “List of Diag-
nostic Trouble
Code (DTC).”
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
Page 1321 of 2453

EN(H6DO)(diag)-160
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AH:DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP
FUEL CONTROL
DTC DETECTING CONDITION:
•Detected when two consecutive driving cycles with fault occur.
•GENERAL DESCRIPTION
TURE FOR CLOSED LOOP FUEL CONTROL, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine would not return to idling.
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Tr o u b l e C o d e
(DTC).”
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0125.
Go to step 2.
2CHECK TIRE SIZE.Is the tire size as specified?
and the same size as other
three wheels?
Go to step 3.Replace the tire.
3CHECK ENGINE COOLANT.
Check the following items:
•Amount of engine coolant
•Engine coolant freeze
•Contamination of engine coolant
Is the engine coolant normal? Go to step 4.Fill or replace the
engine coolant.
CO(H6DO)-11,
INSPECTION,
Engine Coolant.>
4CHECK THERMOSTAT.Does the thermostat remain
opened?
Replace the ther-
mostat.
CO(H6DO)-14,
Thermostat.>
Replace the
engine coolant
temperature sen-
sor.
FU(H6DO)-17,
Engine Coolant
Te m p e r a t u r e S e n -
sor.>
Page 1323 of 2453
EN(H6DO)(diag)-162
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 2.
2CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Measure the resistance between engine cool-
ant temperature sensor terminals when the
engine coolant is cold and after warmed-up.
Te r m i n a l s
No. 1 — No. 2:
Is the resistance of engine
coolant temperature sensor dif-
ferent between when engine
coolant is cold and after
warmed-up?
Contact with SOA
Service Center.
Replace the
engine coolant
temperature sen-
sor.
FU(H6DO)-17,
Engine Coolant
Te m p e r a t u r e S e n -
sor.>
Page 1324 of 2453

EN(H6DO)(diag)-163
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AJ:DTC P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW
THERMOSTAT REGULATING TEMPERATURE)
DTC DETECTING CONDITION:
•Detected when two consecutive driving cycles with fault occur.
•GENERAL DESCRIPTION
TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE), Diagnostic Trouble Code
(DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Thermostat remains open.
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
Step Check Yes No
1CHECK VEHICLEHas the vehicle driven or idled
with the engine partially sub-
merged under water?
In this case, it is
not necessary to
inspect DTC
P0128.
Go to step 2.
2CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 3.
3CHECK ENGINE COOLANT.Are the coolant level and mix-
ture ratio of engine coolant to
anti-freeze solution correct?
Go to step 4.Replace engine
coolant.
CO(H6DO)-10,
REPLACEMENT,
Engine Coolant.>
4CHECK RADIATOR FAN.
1) Start the engine.
2) Check radiator fan operation.
Does the radiator fan continu-
ously rotate for more than 3
minutes during idling?
Repair radiator fan
circuit.
CO(H6DO)-21,
Radiator Main Fan
and Fan Motor.>
and
CO(H6DO)-25,
Radiator Sub Fan
and Fan Motor.>
Replace the ther-
mostat.
CO(H6DO)-14,
Thermostat.>
Page 1333 of 2453
EN(H6DO)(diag)-172
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check DTC using
“List of Diagnostic
Tr o u b l e C o d e
(DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0133.
Go to step 2.
2 CHECK EXHAUST SYSTEM.
NOTE:Check the following item.
•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
Is there any fault in exhaust
system?
Repair the exhaust
system.
Replace the front
oxygen (A/F) sen-
sor.
FU(H6DO)-28,
Fr o nt Ox yg en ( A /
F) Sensor.>
Page 1339 of 2453

EN(H6DO)(diag)-178
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check DTC using
“List of Diagnostic
Tr o u b l e C o d e
(DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0137.
Go to step 2.
2CHECK REAR OXYGEN SENSOR DATA.
1) Warm-up the engine until engine coolant
temperature is above 70°C (158°F), and keep
the engine speed at 5,000 rpm.
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
•General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
Is the voltage more than 490
mV?
Go to step 5.Go to step 3.
3CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness
between ECM and rear oxygen sensor con-
nector.
Connector & terminal
(B135) No. 4 — (E61) No. 3:
(B135) No. 30 — (E61) No. 4:
Is the resistance more than
3Ω?
Repair the open
circuit of harness
between ECM and
rear oxygen sen-
sor connector.
Go to step 4.
4CHECK HARNESS BETWEEN REAR OXY-
GEN SENSOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor harness connector and chassis ground.
Connector & terminal
(E61) No. 3 (+) — Chassis ground (–):
Is the voltage 0.2 — 0.5 V? Replace the rear
oxygen sensor.
FU(H6DO)-30,
Rear Oxygen Sen-
sor.>
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following item:
•Open circuit
of harness be-
tween rear oxy-
gen sensor and
ECM connector
•Poor contact
in rear oxygen
sensor connec-
tor
•Poor contact
in ECM connec-
tor
Page 1343 of 2453

EN(H6DO)(diag)-182
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check DTC using
“List of Diagnostic
Tr o u b l e C o d e
(DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0138.
Go to step 2.
2CHECK REAR OXYGEN SENSOR DATA.
1) Warm-up the engine until engine coolant
temperature is above 70°C (158°F), and rap-
idly reduce the engine speed from 5,000 rpm.
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
•General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
Is the voltage 250 mV or less? Go to step 5.Go to step 3.
3CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness
between ECM and rear oxygen sensor con-
nector.
Connector & terminal
(B135) No. 4 — (E61) No. 3:
(B135) No. 30 — (E61) No. 4:
Is the resistance more than
3Ω?
Repair the open
circuit of harness
between ECM and
rear oxygen sen-
sor connector.
Go to step 4.
4CHECK HARNESS BETWEEN REAR OXY-
GEN SENSOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor harness connector and chassis ground.
Connector & terminal
(E61) No. 3 (+) — Chassis ground (–):
Is the voltage 0.2 — 0.5 V? Replace the rear
oxygen sensor.
FU(H6DO)-30,
Rear Oxygen Sen-
sor.>
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following item:
•Open circuit
of harness be-
tween rear oxy-
gen sensor and
ECM connector
•Poor contact
in rear oxygen
sensor connec-
tor
•Poor contact
in ECM connec-
tor
Page 1347 of 2453

EN(H6DO)(diag)-186
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check DTC using
“List of Diagnostic
Tr o u b l e C o d e
(DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0139.
Go to step 2.
2CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness
between ECM and rear oxygen sensor con-
nector.
Connector & terminal
(B135) No. 4 — (E61) No. 3:
Is the resistance less than 1
Ω?
Go to step 3.Repair the open
circuit of harness
between ECM and
rear oxygen sen-
sor connector.
3CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance between rear oxygen
sensor harness connector and chassis ground.
Connector & terminal
(E61) No. 3 — Chassis ground
Is the resistance more than 1
MΩ?
Go to step 4.Repair the chas-
sis short circuit of
harness.
4CHECK REAR OXYGEN SENSOR.
Measure the resistance between connector
terminals of rear oxygen sensor.
Te r m i n a l s
No. 3 — No. 4
Is the resistance less than 1
Ω?
Replace the rear
oxygen sensor.
FU(H6DO)-30,
Rear Oxygen Sen-
sor.>
Te m p o r a r y p o o r
contact occurs.
Check poor con-
tact of connector.