
EN(H4DOTC)-220
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”.
List of Diagnostic
Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0519.Go to step 2.
2 CHECK AIR INTAKE SYSTEM.
1) Turn the ignition switch to ON.
2) Start and idle the engine.
3) Check the following items:
Loose installation of intake manifold, idle air
control solenoid valve and throttle body
Cracks of intake manifold gasket, idle air
control solenoid valve gasket and throttle body
gasket
Disconnections of vacuum hosesIs there any fault in air intake
system?Repair air suction
and leaks.Go to step 3.
3 CHECK THROTTLE CABLE.Does the throttle cable have
play for adjustment?Go to step 4.Adjust throttle
cable.
INSTALLATION,
Accelerator Con-
trol Cable.>
4 CHECK AIR BY-PASS LINE.
1) Turn the ignition switch to OFF.
2) Remove the idle air control solenoid valve
from the throttle body.
3) Confirm that there are no foreign particles
in by-pass air line.Are foreign particles in by-pass
air line?Remove foreign
particles from by-
pass air line.Replace the idle
air control solenoid
valve.
Idle Air Control
Solenoid Valve.>

EN(H4DOTC)-222
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of exhaust temperature sen-
sor signal using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”.
OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is engine coolant temperature
more than 1200°C (2192°F)?Go to step 2.Repair the poor
contact.
N
OTE:
In this case repair
the following:
Poor contact of
exhaust tempera-
ture sensor
Poor contact in
ECM
Poor contact in
joint connector
2 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from exhaust
temperature sensor.
3) Turn the ignition switch to ON.
4) Read the data of exhaust temperature sen-
sor signal using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”.
OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the temperature less than
372°C (702°F)?Replace the
exhaust tempera-
ture sensor.
49, Exhaust Tem-
perature Sensor.>Repair ground
short circuit in har-
ness between
exhaust tempera-
ture sensor and
ECM connector.

EN(H4DOTC)-229
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from TCM.
4) Measure the resistance between connec-
tors of ECM and TCM.
Connector & terminal
(B137) No. 18 — (B55) No. 3:
(B137) No. 26 — (B54) No. 12:Is the resistance less than 1
Ω?Go to step 2.Repair the har-
ness connector.
2 CHECK HARNESS BETWEEN ECM AND
TCM.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 18 — Chassis ground:
(B137) No. 26 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the har-
ness connector.
3 CHECK HARNESS BETWEEN ECM AND
TCM.
Measure the resistance of ECM connectors.
Connector & terminal
(B137) No. 18 — (B137) No. 26:Is the resistance more than 1
MΩ?Go to step 4.Repair the har-
ness connector.
4 CHECK AT SYSTEM STATUS.
Check the AT using Subaru Select Monitor.Does the Subaru Select Moni-
tor display DTC P1718?Inspect the AT sys-
tem.Replace the ECM.
Engine Control
Module (ECM).>

EN(H4DOTC)-234
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector.
3) Turn the ignition switch to ON.
4) While operating the radiator fan relay, mea-
sure voltage between ECM terminal and
ground.
N
OTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor.For procedure, re-
fer to “Compulsory Valve Operation Check
Mode”.
Connector & terminal
(B135) No. 24 (+) — Chassis ground (
−):
(B135) No. 25 (+) — Chassis ground (
−):Does the voltage vary between
0 — 10 V?Repair the poor
contact in ECM
connector.Go to step 2.
2 CHECK GROUND SHORT CIRCUIT IN RADI-
ATOR FAN RELAY CONTROL CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B135) No. 24 — Chassis ground:
(B135) No. 25 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in
radiator fan relay
control circuit.
3 CHECK POWER SUPPLY FOR RELAY.
1) Remove the main fan relay 1 and sub fan
relay from A/C relay holder.
2) Turn the ignition switch to ON.
3) Measure the voltage between fuse and
relay box (F/B) connector and chassis ground.
Connector & terminal
(F27) No. 25 (+) — Chassis ground (
−):
(F27) No. 34 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 4.Repair open circuit
in harness
between ignition
switch and fuse
and relay box (F/B)
connector.
4 CHECK MAIN FAN RELAY 1.
1) Turn the ignition switch to OFF.
2) Measure the resistance of main fan relay 1
terminals.
Te r m i n a l s
No. 32 — No. 34:Is the resistance 87 — 107 Ω? Go to step 5.Replace the main
fan relay 1.
5 CHECK SUB FAN RELAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between sub fan
relay terminals.
Te r m i n a l s
No. 25 — No. 27:Is the resistance 87 — 107 Ω? Go to step 6.Replace the sub
fan relay.
6 CHECK OPEN CIRCUIT IN FAN RELAY
CONTROL CIRCUIT.
Measure the resistance of harness between
ECM and fan relay connector.
Connector & terminal
(B135) No. 24 — (F27) No. 27:
(B135) No. 25 — (F27) No. 32:Is the resistance less than 1
Ω?Go to step 7.Repair harness
and connector.
N
OTE:
In this case repair
the following:
Open circuit in
harness between
ECM and fan relay
connector
Poor contact in
coupling connector

EN(H4DOTC)-238
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BU:DTC P0700 TRANSMISSION CONTROL SYSTEM (MIL REQUEST)
NOTE:
For the diagnostic procedure, refer to AT section.
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector.
3) Turn the ignition switch to ON.
4) While operating the radiator fan relay, mea-
sure voltage between ECM and chassis
ground.
N
OTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor.For procedure, re-
fer to “Compulsory Valve Operation Check
Mode”.
Connector & terminal
(B135) No. 24 (+) — Chassis ground (
−):
(B135) No. 25 (+) — Chassis ground (
−):Does the voltage vary between
0 — 10 V?Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.In this
case, repair poor
contact in ECM
connector.Go to step 2.
2 CHECK SHORT CIRCUIT IN RADIATOR FAN
RELAY CONTROL CIRCUIT.
1) Turn the ignition switch to OFF.
2) Remove the main fan relay 1, sub fan relay
and fan mode relay.
3) Disconnect the test mode connectors
4) Turn the ignition switch to ON.
5) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B135) No. 24 (+) — Chassis ground (
−):
(B135) No. 25 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in
radiator fan relay
control cir-
cuit.After repair,
replace the ECM.
Engine Control
Module (ECM).>Go to step 3.
3 CHECK MAIN FAN RELAY 1.
1) Turn the ignition switch to OFF.
2) Remove the main fan relay1.
3) Measure the resistance of main fan relay 1
terminals.
Te r m i n a l s
No. 30 — No. 31:Is the resistance less than 1
Ω?Replace the main
fan relay 1 and
ECM.
Engine Control
Module (ECM).>Go to step 4.
4 CHECK SUB FAN RELAY.
1) Remove the sub fan relay.
2) Measure the resistance between sub fan
relay terminals.
Te r m i n a l s
No. 28 — No. 29:Is the resistance less than 1
Ω?Replace the sub
fan relay and
ECM.
Engine Control
Module (ECM).>Go to step 5.
5 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
Engine Control
Module (ECM).>

EN(H4DOTC)-240
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Shift the select lever to other than “N” and
“P” ranges.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage 4.5 — 5.5 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T3).
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B137) No. 9 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
3 CHECK TRANSMISSION HARNESS CON-
NECTOR.
1) Disconnect the connector from inhibitor
switch.
2) Measure the resistance of harness
between transmission harness connector and
engine ground.
Connector & terminal
(T3) No. 12 — Engine ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between
transmission har-
ness and inhibitor
switch connector.
4 CHECK INHIBITOR SWITCH.
Measure the resistance between inhibitor
switch connector the receptacle’s terminals in
selector lever except for “N” range.
Te r m i n a l s
No. 7 — No. 12:Is the resistance more than 1
MΩ?Go to step 5.Replace the inhibi-
tor switch.
Switch.>
5 CHECK SELECTOR CABLE CONNECTION.Is there any fault in selector
cable connection to inhibitor
switch?Repair selector
cable connection.
Select Cable.>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

EN(H4DOTC)-242
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in neutral.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
1) Place the shift lever except in neutral.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 3.Go to step 4.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
4 CHECK NEUTRAL POSITION SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion harness.
3) Place the shift lever in neutral.
4) Measure the resistance between transmis-
sion harness and connector terminals.
Connector & terminal
(T9) No. 1 — No. 3:Is the resistance more than 1
MΩ?Go to step 5.Repair short circuit
in transmission
harness or replace
the neutral position
switch.
5 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever except in neutral.
2) Measure the resistance between transmis-
sion harness connector terminals.
Te r m i n a l s
No. 1 — No. 3:Is the resistance less than 1
Ω?Go to step 6.Repair short circuit
in transmission
harness or replace
the neutral position
switch.
6 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
7 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness
between ECM and transmission harness con-
nector.
Connector & terminal
(B137) No. 9 — (B128) No. 1:Is the resistance less than 1
Ω?Go to step 8.Repair open circuit
in harness
between ECM and
transmission har-
ness connector.
8 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 1 — Engine ground:Is the resistance less than 5
Ω?Go to step 9.Repair open circuit
between transmis-
sion harness con-
nector and engine
ground terminal.
9 CHECK POOR CONTACT.
Check poor contact in transmission harness
connector.Is there poor contact in trans-
mission harness connector?Repair poor con-
tact in transmis-
sion harness
connector.Contact the SUB-
ARU dealer.

EN(H4DOTC)-247
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever except in neutral posi-
tion.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
1) Place the shift lever in neutral position.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 3.Go to step 4.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
4 CHECK INPUT SIGNAL FROM ECM.
1) Disconnect the connector from ECM.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and trans-
mission harness
connector.Go to step 5.
5 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T9).
3) Measure the resistance of harness
between ECM and neutral switch connector.
Connector & terminal
(B137) No. 9 — (B128) No. 1:Is the resistance less than 1
Ω?Go to step 6.Repair the har-
ness and connec-
tor.
NOTE:
In this case repair
the following:
Open circuit in
harness between
ECM and trans-
mission harness
connector
Poor contact in
transmission har-
ness connector.
Poor contact in
ECM connector.
6 CHECK NEUTRAL POSITION SWITCH
GROUND LINE.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 3 — Engine ground:Is the resistance less than 5
Ω?Go to step 7.Repair open circuit
in the neutral posi-
tion switch ground
line.
7 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever except in neutral posi-
tion.
2) Measure the resistance between transmis-
sion harness connector socket terminals.
Te r m i n a l s
No. 1 — No. 3:Is the resistance less than 1
Ω?Go to step 8.Replace the neu-
tral position switch.
8 CHECK POOR CONTACT.
Check poor contact in transmission harness
connector.Is there poor contact in trans-
mission harness connector?Repair poor con-
tact in transmis-
sion harness
connector.Contact the SUB-
ARU dealer.