Page 1311 of 2453

EN(H6DO)(diag)-150
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture 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 engine coolant tempera-
ture above 150°C (302°F) ?
Go to step 2.Repair the poor
contact.
NOTE:
In this case, repair
the following item:
•Poor contact
of engine cool-
ant tempera-
ture sensor
•Poor contact
in ECM
•Poor contact
of coupling con-
nector
•Poor contact
of joint connec-
tor
2CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the engine
coolant temperature sensor.
3) Turn the ignition switch to ON.
4) Read the data of engine coolant tempera-
ture 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 engine coolant tempera-
ture less than –40°C (–40°F) ?
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.>
Repair the ground
short circuit of har-
ness between
engine coolant
temperature sen-
sor and ECM con-
nector.
Page 1312 of 2453
EN(H6DO)(diag)-151
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AE:DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
•Immediately at fault recognition
•GENERAL DESCRIPTION
CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
•Hard to start
•Erroneous idling
•Poor driving performance
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
WIRING DIAGRAM:
EN-03661
2934
198
B134ECM
12
E2
B21
E8
ENGINECOOLANTTEMPERATURE SENSOR
E8
B21
123412131415567816171819910 1120212223 24 25 2627 28 29 3031 32 33
3534 37363938 41404342 4445 47464948 51505352 54
12
B134
85610 11 12 13 14 157213416
3019 20 2228 29
91718252123 24323126 2733 34
Page 1313 of 2453

EN(H6DO)(diag)-152
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture 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 engine coolant tempera-
ture less than –40°C (–40°F) ?
Go to step 2.Repair the poor
contact.
NOTE:
In this case, repair
the following item:
•Poor contact
of engine cool-
ant tempera-
ture sensor
•Poor contact
in ECM
•Poor contact
of coupling con-
nector
•Poor contact
of joint connec-
tor
2CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the engine
coolant temperature sensor.
3) Measure the voltage between engine cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
Is the voltage more than 10 V? Repair the battery
short circuit of har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 3.
3CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between engine cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
Is the voltage more than 10 V? Repair the battery
short circuit of har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 4.
Page 1314 of 2453

EN(H6DO)(diag)-153
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
4CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
Measure the voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
Is the voltage more than 4 V? Go to step 5.Repair the har-
ness and connec-
tor.
NOTE:In this case, repair
the following item:
•Open circuit
of harness be-
tween ECM and
engine coolant
temperature
sensor connec-
tor
•Poor contact
of engine cool-
ant tempera-
ture sensor
connector
•Poor contact
in ECM connec-
tor
•Poor contact
of coupling con-
nector
•Poor contact
of joint connec-
tor
5CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between engine coolant temperature sensor
connector and engine ground.
Connector & terminal
(E8) No. 1 — Engine ground:
Is the resistance less than 5
Ω?
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.>
Repair the har-
ness and connec-
tor.
NOTE:In this case, repair
the following item:
•Open circuit
of harness be-
tween ECM and
engine coolant
temperature
sensor connec-
tor
•Poor contact
of engine cool-
ant tempera-
ture sensor
connector
•Poor contact
in ECM connec-
tor
•Poor contact
of coupling con-
nector
•Poor contact
of joint connec-
tor
Step Check Yes No
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 1322 of 2453
EN(H6DO)(diag)-161
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AI: DTC P0126 INSUFFICIENT COOLANT TEMPERATURE FOR STABLE OPER-
ATION
DTC DETECTING CONDITION:
•Detected when two consecutive driving cycles with fault occur.
•GENERAL DESCRIPTION
TURE FOR STABLE OPERATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
•Hard to start
•Erroneous idling
•Poor driving performance
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
WIRING DIAGRAM:
EN-03661
2934
198
B134ECM
12
E2
B21
E8
ENGINECOOLANTTEMPERATURE SENSOR
E8
B21
123412131415567816171819910 1120212223 24 25 2627 28 29 3031 32 33
3534 37363938 41404342 4445 47464948 51505352 54
12
B134
85610 11 12 13 14 157213416
3019 20 2228 29
91718252123 24323126 2733 34
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.>