Subaru 2004 LEGACY User manual

FUJI HEAVY INDUSTRIES LTD. G2320GE2
2004 LEGACY SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 1
This service manual has been prepared
to provide SUBARU service personnel
with the necessary information and data
for the correct maintenance and repair
of SUBARU vehicles.
This manual includes the procedures
for maintenance, disassembling, reas-
sembling, inspection and adjustment of
components and diagnostics for guid-
ance of experienced mechanics.
Please peruse and utilize this manual
fully to ensure complete repair work for
satisfying our customers by keeping
their vehicle in optimum condition.
When replacement of parts during
repair work is needed, be sure to use
SUBARU genuine parts.
All information, illustration and specifi-
cations contained in this manual are
based on the latest product information
available at the time of publication
approval.
FUEL INJECTION (FUEL SYSTEMS) FU(H4SO 2.0)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SO 2.0)
INTAKE (INDUCTION) IN(H4SO 2.0)
MECHANICAL ME(H4SO 2.0)
EXHAUST EX(H4SO 2.0)
COOLING CO(H4SO 2.0)
LUBRICATION LU(H4SO 2.0)
SPEED CONTROL SYSTEMS SP(H4SO 2.0)
IGNITION IG(H4SO 2.0)
STARTING/CHARGING SYSTEMS SC(H4SO 2.0)
ENGINE (DIAGNOSTICS) EN(H4SO 2.0)
(diag)
FUEL INJECTION (FUEL SYSTEMS) FU(H4SO 2.5)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SO 2.5)
INTAKE (INDUCTION) IN(H4SO 2.5)
MECHANICAL ME(H4SO 2.5)
EXHAUST EX(H4SO 2.5)
COOLING CO(H4SO 2.5)

2003 LEGACY SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 1
G2320GE2
LUBRICATION LU(H4SO 2.5)
SPEED CONTROL SYSTEMS SP(H4SO 2.5)
IGNITION IG(H4SO 2.5)
STARTING/CHARGING SYSTEMS SC(H4SO 2.5)
ENGINE (DIAGNOSTICS) EN(H4SO 2.5)
(diag)

ENGINE (DIAGNOSTICS)
EN(H4SO 2.5)(diag)
Page
1. Basic Diagnostic Procedure........................................................................2
2. Check List for Interview...............................................................................3
3. General Description ....................................................................................5
4. Electrical Component Location ...................................................................8
5. Engine Control Module (ECM) I/O Signal .................................................17
6. Engine Condition Data..............................................................................21
7. Data Link Connector .................................................................................22
8. OBD-II General Scan Tool........................................................................23
9. Subaru Select Monitor...............................................................................26
10. Read Diagnostic Trouble Code (DTC)......................................................33
11. Inspection Mode........................................................................................34
12. Drive Cycle................................................................................................39
13. Clear Memory Mode..................................................................................41
14. Compulsory Valve Operation Check Mode...............................................42
15. Malfunction Indicator Light........................................................................44
16. Diagnostics for Engine Starting Failure.....................................................54
17. List of Diagnostic Trouble Code (DTC).....................................................70
18. Diagnostic Procedure with Diagnostic Trouble Code (DTC).....................80
19. General Diagnostic Table........................................................................261

EN(H4SO 2.5)(diag)-80
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
18.Diagnostic Procedure with Diagnostic Trouble Code (DTC)
A: DTC P0030 HO2S HEATER CONTROL CIRCUIT (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-01992
34
12
56
B327
SBF-6
E
E
B327 E24
6
4
5
3
2
1
4
6 3 1
25 33 26
3 2
6 7
52
B134
B21
E2
B21 E2
50
51
3 4
E2
B21
E
B21
1234
12 13 14 15
5678
16 17 18 19
9 10 11
20 21 22
23 24 25 26 27 28 29 30 31 32 33
3534 3736 3938 4140
4342 44 45 4746
4948 5150 5352 54
E24
B134
56 7
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17
18 19 20 21
33 3429 3230 31
ECM
BATTERY
FRONT OXYGEN
(A/F) SENSOR
OXYGEN (A/F)
SENSOR RELAY
13
456
2

EN(H4SO 2.5)(diag)-81
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
4) Measure the resistance of harness
between ECM and front oxygen (A/F) sensor
connector.
Connector & terminal
(B134) No. 2 — (E24) No. 6:
(B134) No. 3 — (E24) No. 6:
Is the resistance less than 1
Ω?Go to step 3. Repair the open circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
ECM and front oxygen (A/F) sensor connector.
Connector & terminal
(B134) No. 26 — (E24) No. 1:
(B134) No. 33 — (E24) No. 3:
Is the resistance less than 1
Ω?Go to step 4. Repair the open circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
main relay and front oxygen (A/F) sensor con-
nector.
Connector & terminal
(B327) No. 4 — (E24) No. 4:
Is the resistance less than 1
Ω?Go to step 5. Repair the open circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
5 CHECK FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen
(A/F) sensor connector terminals.
Terminals
No. 4 — No. 6:
Is the resistance less than 5
Ω?Go to step 6. Replace the front oxygen (A/F) sen-
sor. <Ref. to
FU(H4SO 2.5)-34,
Front Oxygen (A/
F) Sensor.>
6 CHECK POOR CONTACT.
Check the poor contact in ECM and front oxy-
gen (A/F) sensor connector.
Is there poor contact inECM or
front oxygen (A/F) sensor con-
nector?
Repair the poor
contact in ECM or
front oxygen (A/F)
sensor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4SO 2.5)-34,
Front Oxygen (A/
F) Sensor.>

EN(H4SO 2.5)(diag)-82
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
B: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-01992
34
12
56
B327
SBF-6
E
E
B327 E24
6
4
5
3
2
1
4
6 3 1
25 33 26
3 2
6 7
52
B134
B21
E2
B21 E2
50
51
3 4
E2
B21
E
B21
1234
12 13 14 15
5678
16 17 18 19
9 10 11
20 21 22
23 24 25 26 27 28 29 30 31 32 33
3534 3736 3938 4140
4342 44 45 4746
4948 5150 5352 54
E24
B134
56 7
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17
18 19 20 21
33 3429 3230 31
ECM
BATTERY
FRONT OXYGEN
(A/F) SENSOR
OXYGEN (A/F)
SENSOR RELAY
13
456
2

EN(H4SO 2.5)(diag)-83
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 CHECK ANY OTHER DTC ON DISPLAY. Do DTC P0031 and P0037
appear at the same time on the
Subaru Select Monitor?
Go to step 3. Go to step 6.
3 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from front oxygen
(A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(E24) No. 4 (+) — Engine ground (
− ):
Is the voltage more than 10 V? Go to step 4. Repair the power
supply line.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
main relay and
front oxygen (A/F)
sensor connector
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
main relay connec-
tor
4 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 6 — Chassis ground:
(B134) No. 7 — Chassis ground:
Is the resistance less than 5
Ω?Go to step 5. Repair the har- ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and engine
ground terminal
• Poor contact in
ECM connector.
• Poor contact in
coupling connector
5 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO2.5)(diag)-26, Subaru Select Mon-
itor.>
Is the current more than 0.2 A? Repair the poor
contact connector.
NOTE:
In this case, repair
the following:
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
ECM connector.
Go to step 6.

EN(H4SO 2.5)(diag)-84
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK INPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
− ):
(B134) No. 3 (+) — Chassis ground (
− ):
Is the voltage less than 1 V? Go to step 8. Go to step 7.
7 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
− ):
(B134) No. 3 (+) — Chassis ground (
− ):
Does the voltage change by
shaking the ECM harness and
connector while monitoring the
value of voltage meter?
Repair the poor
contact in ECM
connector.
Go to step 8.
8 CHECK FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between front oxy-
gen (A/F) sensor connector terminals.
Terminals
No. 4 — No. 6:
Is the resistance less than 10
Ω?Repair the har- ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open or ground
short circuit in har-
nessbetweenfront
oxygen (A/F) sen-
sor and ECM con-
nector
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
ECM connector
Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4SO 2.5)-34,
Front Oxygen (A/
F) Sensor.>
Step Check Yes No

EN(H4SO 2.5)(diag)-85
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
C: DTC P0032 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-01992
34
12
56
B327
SBF-6
E
E
B327 E24
6
4
5
3
2
1
4
6 3 1
25 33 26
3 2
6 7
52
B134
B21
E2
B21 E2
50
51
3 4
E2
B21
E
B21
1234
12 13 14 15
5678
16 17 18 19
9 10 11
20 21 22
23 24 25 26 27 28 29 30 31 32 33
3534 3736 3938 4140
4342 44 45 4746
4948 5150 5352 54
E24
B134
56 7
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17
18 19 20 21
33 3429 3230 31
ECM
BATTERY
FRONT OXYGEN
(A/F) SENSOR
OXYGEN (A/F)
SENSOR RELAY
13
456
2

EN(H4SO 2.5)(diag)-86
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
− ):
(B134) No. 3 (+) — Chassis ground (
− ):
Is the voltage more than 8 V? Go to step 3. Go to step 4.
3 CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1) Turn the ignition switch to OFF.
2) Repair the battery short circuit in harness
between ECM and front oxygen (A/F) sensor
connector.
3) Turn the ignition switch to ON.
4) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO2.5)(diag)-26, Subaru Select Mon-
itor.>
Is the current more than 2.3 A? Replace the ECM.
<Ref. to FU(H4SO
2.5)-36, Engine
Control Module
(ECM).>
END.
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
− ):
(B134) No. 3 (+) — Chassis ground (
− ):
Does the voltage change by
shaking the ECM harness and
connector?
Repair the battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
END.

EN(H4SO 2.5)(diag)-87
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
D: DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-02458
B327
B19
34
5 6
12
12
34
BATTERY
B327
OXYGEN SENSOR
RELAY
1
2
4
6
3
5
B2
D24 C35 D31
A6 A7
REAR
OXYGEN SENSOR
ECM
1
3 4
2
52
B21
B19
E2
B135
B:
D: B137
SBF-6
C: B136
EE
A: B134
B137
567
8
21
9
43
10
22 23
11 12 13 14 15
24 25
26
16 17
18 19 20 21
27 28 29 30 31
B134
56 7
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17
18 19 20 21
33 3429 3230 31
B136
56
78
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16
17 18 19 20 21
33 34
29 32 30 31 35
B135
567
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17 18 19
20 21
29 30 31 32 33 34 35
A:
B:
C:
D:
B21
1234
12 13 14 15
5678
16 17 18 19
9 10 11
20 21 22
23 24 25 26 27 28 29 30 31 32 33
3534 3736 3938 4140
4342 44 45 4746
4948 5150 5352 54
1234
5 6 7 8
B83
*: TERMINAL No. RANDOM ARRANGEMENT
B83
B83
4
8
*
*
RHD
RHD
LHD
LHD

EN(H4SO 2.5)(diag)-88
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 CHECK GROUND CIRCUIT OF ECM.
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
(B134) No. 6 — Chassis ground:
(B134) No. 7 — Chassis ground:
Is the resistance less than 5
Ω?Go to step 3. Repair the har- ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and engine
ground terminal
• Poor contact in
ECM connector
• Poor contact in
coupling connector
3 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of rear oxygen sensor heater
current using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO2.5)(diag)-26, Subaru Select Mon-
itor.>
Is the current more than 0.2 A? Repair the con-
nector.
NOTE:
In this case, repair
the following:
• Poor contact in
rear oxygen sen-
sor connector
• Poor contact in
rear oxygen sen-
sor connecting
harness connector
• Poor contact in
ECM connector
Go to step 4.
4 CHECK OUTPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
− ):
Is the voltage less than 1 V? Go to step 7. Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
− ):
Does the voltage change by
shaking the ECM harness and
connector while monitoring the
value of voltage meter?
Repair the poor
contact in ECM
connector.
Go to step 6.

EN(H4SO 2.5)(diag)-89
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK OUTPUT SIGNAL FROM ECM.
1) Disconnect the connector from rear oxygen
sensor.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
− ):
Is the voltage less than 1 V? Replace the ECM.
<Ref. to FU(H4SO
2.5)-36, Engine
Control Module
(ECM).>
Repair the battery
short circuit in har-
ness between
ECM and rear oxy-
gen sensor con-
nector. After
repair, replace the
ECM. <Ref. to
FU(H4SO 2.5)-36,
Engine Control
Module (ECM).>
7 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
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 connector and chassis ground.
Connector & terminal
(B19) No. 2 (+) — Chassis ground (
− ):
Is the voltage more than 10 V? Go to step 8. Repair the power
supply line.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
main relay and
rear oxygen sen-
sor connector
• Poor contact in
rear oxygen sen-
sor connector
• Poor contact in
coupling connector
8 CHECK REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between rear oxy-
gen (A/F) sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than 30
Ω?Repair the har- ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
rear oxygen sen-
sor and ECM con-
nector
• Poor contact in
rear oxygen sen-
sor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Replace the rear
oxygen sensor.
<Ref. to FU(H4SO
2.5)-35, Rear Oxy-
gen Sensor.>
Step Check Yes No

EN(H4SO 2.5)(diag)-90
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
E: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-02458
B327
B19
34
5 6
12
12
34
BATTERY
B327
OXYGEN SENSOR
RELAY
1
2
4
6
3
5
B2
D24 C35 D31
A6 A7
REAR
OXYGEN SENSOR
ECM
1
3 4
2
52
B21
B19
E2
B135
B:
D: B137
SBF-6
C: B136
EE
A: B134
B137
567
8
21
9
43
10
22 23
11 12 13 14 15
24 25
26
16 17
18 19 20 21
27 28 29 30 31
B134
56 7
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17
18 19 20 21
33 3429 3230 31
B136
56
78
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16
17 18 19 20 21
33 34
29 32 30 31 35
B135
567
8
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16 17 18 19
20 21
29 30 31 32 33 34 35
A:
B:
C:
D:
B21
1234
12 13 14 15
5678
16 17 18 19
9 10 11
20 21 22
23 24 25 26 27 28 29 30 31 32 33
3534 3736 3938 4140
4342 44 45 4746
4948 5150 5352 54
1234
5 6 7 8
B83
*: TERMINAL No. RANDOM ARRANGEMENT
B83
B83
4
8
*
*
RHD
RHD
LHD
LHD

EN(H4SO 2.5)(diag)-91
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
− ):
Is the voltage more than 8 V? Go to step 3. Go to step 4.
3 CHECK CURRENT DATA.
1) Turn the ignition switch to OFF.
2) Repair the battery short circuit in harness
between ECM and rear oxygen sensor con-
nector.
3) Turn the ignition switch to ON.
4) Read the data of rear oxygen sensor heater
current using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO2.5)(diag)-26, Subaru Select Mon-
itor.>
Is the current more than 7 A? Replace the ECM.
<Ref. to FU(H4SO
2.5)-36, Engine
Control Module
(ECM).>
END.
4 CHECK POOR CONTACT.
Check poor contact in ECM connector. Is there poor contact in ECM connector? Repair the poor contact in ECM
connector.
END.

EN(H4SO 2.5)(diag)-92
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
F: DTC P0102 MASS OR VOLUME AIR FLOW CIRCUIT LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition.
TROUBLE SYMPTOM:
• Erroneous idling
• Engine stalls.
• Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-02459
B3
BATTERY
E
1
B3
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
ECMB136
SBF-8
34
12
56
B47
2 4 3 5
31
13
23
35
32
MAIN RELAY
B47
1
2
4
6
3
5
1234
5678
B83
B136
56
78
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16
17 18 19 20 21
33 34
29 32 30 31 35
*: TERMINAL No. RANDOM ARRANGEMENT
B83
B83
2
8
*
*
LHD
RHD
LHD
RHD
12345

EN(H4SO 2.5)(diag)-93
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 READ THE DATA CONNECTING SUBARU
SELECT MONITOR.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON, and the Sub-
aru Select Monitor switch to ON.
4) Start the engine.
5) Read the voltage of mass air flow sensor
using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4SO
2.5)(diag)-26, Subaru Select Monitor.>
Is the voltage 0.2 — 4.7 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector or
harness may be
the cause. Repair
harness or con-
nector in the mass
air flow sensor.
NOTE:
In this case, repair
the following:
• Open or ground
short circuit in har-
ness between
mass air flow sen-
sor and ECM con-
nector
• Poor contact in
mass air flow sen-
sor or ECM con-
nector
Go to step 3.
3 CHECK INPUT SIGNAL OF ECM.
Measure the voltage between ECM connector
and chassis ground while engine is idling.
Connector & terminal
(B136) No. 23 (+) — Chassis ground (
− ):
Is the voltage more than 0.2 V? Go to step 5. Go to step 4.
4 CHECK INPUT SIGNAL FOR ECM (USING
SUBARU SELECT MONITOR).
Measure the voltage between ECM connector
and chassis ground while engine is idling.
Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with Subaru
Select Monitor?
Repair the poor
contact in ECM
connector.
Replace the ECM.
<Ref. to FU(H4SO
2.5)-36, Engine
Control Module
(ECM).>
5 CHECK POWER SUPPLY TO MASS AIR
FLOW SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air
flow sensor.
3) Turn the ignition switch to ON.
4) Measure voltage between mass air flow
sensor connector and chassis ground.
Connector & terminal
(B3) No. 1 (+) — Chassis ground (
− ):
Is the voltage more than 5 V? Go to step 6. Repair the open
circuit between
mass air flow sen-
sor and main relay

EN(H4SO 2.5)(diag)-94
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and mass air flow sensor con-
nector.
Connector & terminal
(B136) No. 23 — (B3) No. 3:
(B136) No. 31 — (B3) No. 2:
(B136) No. 35 — (B3) No. 5:
Is the resistance less than 1
Ω?Go to step 7. Repair the open circuit between
ECM and mass air
flow sensor con-
nector.
7 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 23 — Chassis ground:
(B136) No. 31 — Chassis ground:
(B136) No. 35 — Chassis ground:
Is the resistance more than 1
MΩ?Go to step 8. Repair the ground short circuit
between ECM and
mass air flow sen-
sor connector.
8 CHECK POOR CONTACT.
Check poor contact in mass air flow sensor
connector.
Is there poor contact in mass
air flow sensor connector? Repair the poor contact in mass air
flow sensor con-
nector.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4SO 2.5)-26,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No

EN(H4SO 2.5)(diag)-95
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
G: DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition.
TROUBLE SYMPTOM:
• Erroneous idling
• Engine stalls.
• Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
41, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-34, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK and K4 model
• KA and KS model
NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.
EN-02459
B3
BATTERY
E
1
B3
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
ECMB136
SBF-8
34
12
56
B47
2 4 3 5
31
13
23
35
32
MAIN RELAY
B47
1
2
4
6
3
5
1234
5678
B83
B136
56
78
21
9
43
10
2422 23 25
11 12 13 14 15
26 27
28
16
17 18 19 20 21
33 34
29 32 30 31 35
*: TERMINAL No. RANDOM ARRANGEMENT
B83
B83
2
8
*
*
LHD
RHD
LHD
RHD
12345

EN(H4SO 2.5)(diag)-96
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPTION CODE. Is the option code EC, EK or
K4? Go to step 2. Refer to EN(H4SO 2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
2 READ THE DATA CONNECTING SUBARU
SELECT MONITOR.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON, and the Sub-
aru Select Monitor switch to ON.
4) Start the engine.
5) Read the voltage of mass air flow sensor
using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO2.5)(diag)-26, Subaru Select Mon-
itor.>
Is the voltage 0.2 — 4.7 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air-
flow sensor.
3) Turn the ignition switch to ON.
4) Measure voltage between mass air flow
sensor connector and chassis ground.
Connector & terminal
(B3) No. 3 (+) — Chassis ground (
− ):
Is the voltage more than 5 V? Repair the battery
short circuit in har-
ness between
mass air flow sen-
sor connector and
ECM connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and mass air flow
sensor connector.
Connector & terminal
(B3) No. 2 — (B136) No. 31:
Is the resistance less than 1
Ω?Replace the mass air flow sensor.
<Ref. to FU(H4SO
2.5)-26, Mass Air
Flow and Intake
Air Temperature
Sensor.>
Repair the open
circuit in harness
between mass air
flow sensor con-
nector and ECM
connector.