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 1315 of 2453
EN(H6DO)(diag)-154
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AF:DTC P0122 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT
LOW INPUT
DTC DETECTING CONDITION:
•Immediately at fault recognition
•GENERAL DESCRIPTION
SOR/SWITCH “A” CIRCUIT LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
•Erroneous idling
•Engine stalls.
•Poor driving performance
Page 1317 of 2453

EN(H6DO)(diag)-156
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main throttle sensor signal
using Subaru Select Monitor.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
Is the voltage more than 0.4 V? Go to step 2.Go to step 3.
2CHECK POOR CONTACT.
Check poor contact in connector between
ECM and electronic throttle control.
Is there poor contact in con-
nector between ECM and elec-
tronic throttle control?
Repair the poor
contact.
Te m p o r a r y p o o r
contact occurred,
but it is normal at
present.
3CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Disconnect the connectors from electronic
throttle control.
4) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(B134) No. 18 — (E57) No. 6:
(B134) No. 19 — (E57) No. 5:
Is the resistance less than 1
Ω?
Go to step 4.Repair the open
circuit of harness
connector.
4CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 18 — Chassis ground:
(B134) No. 19 — Chassis ground:
Is the resistance more than 1
MΩ?
Go to step 5.Repair the chas-
sis short circuit of
harness.
5CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 (+) — Engine ground (–):
Is the voltage 4.5 — 5.5 V? Go to step 6.Repair poor con-
tact in ECM con-
nector. Replace
the ECM if defec-
tive.
FU(H6DO)-32,
Engine Control
Module (ECM).>
6CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 6 — Engine ground:
Is the resistance more than
10Ω?
Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the accel-
erator pedal posi-
tion sensor if
defective.
Repair poor con-
tact in ECM con-
nector. Replace
the ECM if defec-
tive.
FU(H6DO)-32,
Engine Control
Module (ECM).>
Page 1318 of 2453
EN(H6DO)(diag)-157
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AG:DTC P0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT
HIGH INPUT
DTC DETECTING CONDITION:
•Immediately at fault recognition
•GENERAL DESCRIPTION
SOR/SWITCH “A” CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
•Erroneous idling
•Engine stalls.
•Poor driving performance
Page 1320 of 2453

EN(H6DO)(diag)-159
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main throttle sensor signal
using Subaru Select Monitor.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
Is the voltage less than 4.63
V?
Go to step 2.Go to step 3.
2CHECK POOR CONTACT.
Check poor contact in connector between
ECM and electronic throttle control.
Is there poor contact in con-
nector between ECM and elec-
tronic throttle control?
Repair the poor
contact.
Te m p o r a r y p o o r
contact occurred,
but it is normal at
present.
3CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Disconnect the connectors from electronic
throttle control.
4) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(B134) No. 18 — (E57) No. 6:
(B134) No. 29 — (E57) No. 3:
Is the resistance less than 1
Ω?
Go to step 4.Repair the open
circuit of harness
connector.
4CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Connect the ECM connector.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5
Ω?
Go to step 5.Repair poor con-
tact in ECM con-
nector. Replace
the ECM if defec-
tive.
FU(H6DO)-32,
Engine Control
Module (ECM).>
5CHECK SENSOR OUTPUT POWER SUP-
PLY.
Measure the voltage between electronic throt-
tle control connector and engine ground.
Connector & terminal
(E57) No. 6 (+) — Engine ground (–):
Is the voltage less than 10 V? Replace the elec-
tronic throttle con-
trol.
FU(H6DO)-11,
Throttle Body.>
Repair the battery
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
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