Subaru 2004 Forester User manual

FUJI HEAVY INDUSTRIES LTD. G8080GE3
2004 FORESTER SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 2
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 SYSTEM) FU(H4DOTC)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICE) EC(H4DOTC)
INTAKE (INDUCTION) IN(H4DOTC)
MECHANICAL ME(H4DOTC)
EXHAUST EX(H4DOTC)
COOLING CO(H4DOTC)
LUBRICATION LU(H4DOTC)
SPEED CONTROL SYSTEM SP(H4DOTC)
IGNITION IG(H4DOTC)
STARTING/CHARGING SYSTEM SC(H4DOTC)
ENGINE (DIAGNOSTIC) EN(H4DOTC)

ENGINE (DIAGNOSTIC)
EN(H4DOTC)
Page
1. Basic Diagnostics Procedure ......................................................................2
2. Check List for Interview...............................................................................4
3. General Description ....................................................................................6
4. Electrical Component Location ...................................................................9
5. Engine Control Module (ECM) I/O Signal .................................................23
6. Engine Condition Data ..............................................................................27
7. Transmission Control Module (TCM) I/O Signal .......................................28
8. Data Link Connector .................................................................................29
9. OBD-II General Scan Tool ........................................................................30
10. Subaru Select Monitor...............................................................................33
11. Read Diagnostic Trouble Code (DTC) ......................................................39
12. Inspection Mode........................................................................................40
13. Drive Cycle................................................................................................45
14. Clear Memory Mode..................................................................................47
15. Compulsory Valve Operation Check Mode ...............................................48
16. Malfunction Indicator Light ........................................................................50
17. Diagnostics for Engine Starting Failure.....................................................59
18. List of Diagnostic Trouble Code (DTC) .....................................................74
19. Diagnostic Procedure with Diagnostic Trouble Code (DTC) .....................80
20. General Diagnostic Table........................................................................295

EN(H4DOTC)-80
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
19.Diagnostic Procedure with Diagnostic Trouble Code (DTC)
A: DTC P0011 “A” CAMSHAFT POSITION - TIMING OVER - ADVANCED OR
SYSTEM PERFORMANCE (BANK 1)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
TROUBLE SYMPTOM:
• Engine stalls.
• Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC ON DISPLAY. Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and idle it.
2) Check the AVCS system operating angle
and oil flow control solenoid valve duty output
using Subaru Select Monitor or OBD-II general
scan tool.
N
O
TE:
• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
Is the AVCS system operating
angle approx. 0 degree and oil
flow control solenoid valve duty
output approx. 10%?
A temporary poor
malfunction. Per-
form the following
to clean oil routing.
Replace the
engine oil, and
then idle the
engine for 5 min-
utes and replace
the oil filter and
engine oil.
Check the follow-
ing and repair or
replace it if neces-
sary.
• Oil pipe (clog-
ging)
• Oil flow con-
trol solenoid
valve (clogging
or dirt of oil
routing, spring
setting, clog-
ging of valve)
• Intake cam-
shaft (dirt, dam-
age of
camshaft)
• Timing belt
(alignment of
timing mark)

EN(H4DOTC)-81
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
B: DTC P0021 “A” CAMSHAFT POSITION - TIMING OVER - ADVANCED OR
SYSTEM PERFORMANCE (BANK 2)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
TROUBLE SYMPTOM:
• Engine stalls.
• Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC ON DISPLAY. Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and idle it.
2) Check the AVCS system operating angle
and oil flow control solenoid valve duty output
using Subaru Select Monitor or OBD-II general
scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
Is the AVCS system operating
angle approx. 0 degree and oil
flow control solenoid valve duty
output approx. 10%?
A temporary poor
malfunction. Per-
form the following
to clean oil routing.
Replace the
engine oil, and
then idle the
engine for 5 min-
utes and replace
the oil filter and
engine oil.
Check the follow-
ing and repair or
replace it if neces-
sary.
• Engine oil
(amount, dirt)
• Oil pipe (clog-
ging)
• Oil flow con-
trol solenoid
valve (clogging
or dirt of oil
routing, spring
setting, clog-
ging of valve)
• Intake cam-
shaft (dirt, dam-
age of
camshaft)
• Timing belt
(alignment of
timing mark)

EN(H4DOTC)-82
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
C: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (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(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
EN-02320
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B100 F2
14 LHD
RHD
LHD
RHD
B100
F2
F60
E3
203
RHD
RHD
6 7
2 3
33 26 25
ECM
B134
: LHD
: LHD
B21 : RHD
: RHD
1
4 2 3
B262
FRONT OXYGEN
(A/F) SENSOR
34
12
56
1234
5678
9
10 11 12
13 14 15 16
B21
F60
B47
B262
B134
F2
LHDLHD
1
2
3
4
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
1234 56789
10 11 12 13 14 15 16 17 18 19 20
: LHD E2 : RHD

EN(H4DOTC)-83
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start the engine, and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connector 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 — (B262)No. 2:
(B134)No. 3 — (B262)No. 2:
Is the resistance less than 1
Ω?
Go to step 2. Repair the open
circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
2 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. 33 — (B262) No. 4:
(B134) No. 26 — (B262) No. 3:
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
main relay and front oxygen (A/F) sensor con-
nector.
Connector & terminal
(B47) No. 4 — (B262) No. 1:
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 FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen
(A/F) sensor connector terminals.
Terminals
No. 2 — No. 1:
Is the resistance less than 5
Ω?
Go to step 5. Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4DOTC)-45,
Front Oxygen (A/
F) Sensor.>
5 CHECK POOR CONTACT.
Check poor contact in ECM and front oxygen
(A/F) sensor connector.
Is there poor contact in ECM or
front oxygen (A/F) sensor con-
nector?
Repair the poor
contact in ECM
and front oxygen
(A/F) sensor.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4DOTC)-45,
Front Oxygen (A/
F) Sensor.>

EN(H4DOTC)-84
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
D: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
EN-02320
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B100 F2
14 LHD
RHD
LHD
RHD
B100
F2
F60
E3
203
RHD
RHD
6 7
2 3
33 26 25
ECM
B134
: LHD
: LHD
B21 : RHD
: RHD
1
4 2 3
B262
FRONT OXYGEN
(A/F) SENSOR
34
12
56
1234
5678
9
10 11 12
13 14 15 16
B21
F60
B47
B262
B134
F2
LHDLHD
1
2
3
4
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
1234 56789
10 11 12 13 14 15 16 17 18 19 20
: LHD E2 : RHD

EN(H4DOTC)-85
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 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
(B262) No. 1 (+) — Engine ground (
− ):
Is the voltage more than 10 V? Go to step 2. Repair the power
supply line.
N
O
TE:
In this case repair
the following:
• Open circuit in
harness between
main relay and
front oxygen (A/F)
sensor
• CHECK POOR
CONTACT OF
FRONT OXYGEN
(A/F) SENSOR.
• Poor contact in
main relay connec-
tor
2 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 3. Repair the har-
ness and connec-
tor.
N
O
TE:
In this case repair
the following:
• Open circuit in
harness between
ECM and engine
ground cable
• Poor contact in
ECM connector.
• Poor contact in
coupling connector
3 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
O
TE:
• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
Is the current more than 0.2 A? Repair poor con-
tact connector.
N
O
TE:
In this case repair
the following:
• Poor contact in
front oxygen (A/F)
sensor 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
(B134) No. 2 (+) — Chassis ground (
− ):
Is the voltage less than 1 V? Go to step 6. Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
− ):
Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?
Repair the poor
contact in ECM
connector.
Go to step 6.

EN(H4DOTC)-86
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(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. 3 (+) — Chassis ground (
− ):
Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with 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. 2 — No. 1:
Is the resistance less than 10
Ω?
Repair the har-
ness and connec-
tor.
N
O
TE:
In this case repair
the following:
• Open or ground
short circuit in har-
ness between front
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(H4DOTC)-45,
Front Oxygen (A/
F) Sensor.>
Step Check Yes No

EN(H4DOTC)-87
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
E: DTC P0032 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
EN-02320
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B100 F2
14 LHD
RHD
LHD
RHD
B100
F2
F60
E3
203
RHD
RHD
6 7
2 3
33 26 25
ECM
B134
: LHD
: LHD
B21 : RHD
: RHD
1
4 2 3
B262
FRONT OXYGEN
(A/F) SENSOR
34
12
56
1234
5678
9
10 11 12
13 14 15 16
B21
F60
B47
B262
B134
F2
LHDLHD
1
2
3
4
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
1234 56789
10 11 12 13 14 15 16 17 18 19 20
: LHD E2 : RHD

EN(H4DOTC)-88
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 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 2.
2 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 or
OBD-II general scan tool.
N
O
TE:
• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
Is the current more than 2.3 A? Replace the ECM.
<Ref. to
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
END.
3 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 harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?
Repair the battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
END.

EN(H4DOTC)-89
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
F: DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
MAIN RELAY
B47
1
2
3
5
4
6
E
T5
*1
*2
B18
3
B122
1
3
T6
REAR
OXYGEN SENSOR
A6 A7
D31 C35
ECM
B135
B136
B :
B134
A :
C :
1
4
B83
B2
D25
B137
D :
EN-02321
: LHD
: RHD
34
12
56
B21
B134
B135
F60
B83
B47
T6
B136
123456
F2
21
4 3
LHD : 5
RHD : 4
LHD : 1
RHD : 1
*1
*2
BATTERY
B100 F2
14 LHD
RHD
LHD
RHD
LHD
RHD
LHD
RHD
4
6
E
B100
F2
F60
E3
203
RHD
LHD
RHD
: LHD B21 : RHD
LHD
: LHD E2 : RHD
B18
B122
B137
2345 6789
11 12 13 14 17 18 19 20
1
10 15 16
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
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
1234
5 6 7 8
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
1234
5678
9
10 11 12
13 14 15 16
1 2
34
4
2
2
T5
B18
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

EN(H4DOTC)-90
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK GROUND CIRCUIT FOR 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 2. Repair the har-
ness and connec-
tor.
N
O
TE:
In this case repair
the following:
• Open circuit in
harness between
ECM and engine
ground cable
• Poor contact in
ECM connector.
• Poor contact in
coupling connector
2 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of rear oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
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 3.
3 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 6. Go to step 4.
4 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 harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?
Repair the poor
contact in ECM
connector.
Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) 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(H4DOTC)-50,
Engine Control
Module (ECM).>
Repair battery
short circuit in har-
ness between
ECM and rear oxy-
gen sensor con-
nector.After repair,
replace the ECM.
<Ref. to
FU(H4DOTC)-50,
Engine Control
Module (ECM).>

EN(H4DOTC)-91
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 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 engine ground or chas-
sis ground.
Connector & terminal
(T6) No. 1 (+) — Chassis ground (
− ):
Is the voltage more than 10 V? Go to step 7. Repair the power
supply line.
N
O
TE:
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
7 CHECK REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between rear oxy-
gen sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than 30
Ω?
Repair the har-
ness and connec-
tor.
N
O
TE:
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(H4DOTC)-47,
Rear Oxygen Sen-
sor.>
Step Check Yes No

EN(H4DOTC)-92
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
G: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
MAIN RELAY
B47
1
2
3
5
4
6
E
T5
*1
*2
B18
3
B122
1
3
T6
REAR
OXYGEN SENSOR
A6 A7
D31 C35
ECM
B135
B136
B :
B134
A :
C :
1
4
B83
B2
D25
B137
D :
EN-02321
: LHD
: RHD
34
12
56
B21
B134
B135
F60
B83
B47
T6
B136
123456
F2
21
4 3
LHD : 5
RHD : 4
LHD : 1
RHD : 1
*1
*2
BATTERY
B100 F2
14 LHD
RHD
LHD
RHD
LHD
RHD
LHD
RHD
4
6
E
B100
F2
F60
E3
203
RHD
LHD
RHD
: LHD B21 : RHD
LHD
: LHD E2 : RHD
B18
B122
B137
2345 6789
11 12 13 14 17 18 19 20
1
10 15 16
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
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
1234
5 6 7 8
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
1234
5678
9
10 11 12
13 14 15 16
1 2
34
4
2
2
T5
B18
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

EN(H4DOTC)-93
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 OFF.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground ( − ):
Is the voltage more than 8 V? Go to step 2. Go to step 3.
2 CHECK CURRENT DATA.
1) Repair battery short circuit in harness
between ECM and rear oxygen sensor con-
nector.
2) Turn the ignition switch to ON.
3) Read the data of rear oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
O
TE:
• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
Is the current more than 7 A? Replace the ECM.
<Ref. to
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
END.
3 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(H4DOTC)-94
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
H: DTC P0068 MANIFOLD PRESSURE SENSOR RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
•LHD model
EN-02322
B122
MANIFOLD
ABSOLUTE
PRESSURE
SENSOR
THROTTLE BODY
2 3
1
16
35
22
ECM
B136
E21
E2
F61
2
1
18 20 16
F74
B200
16
21
1 2 3
F61E21
12
5 6 7 8
13 14 15 16
9 10 11 12
3 4
17 18 19 20
B136 F2
B122
F74
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
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7
1234
567 8
1234 56789
10 11 12 13 14 15 16 17 18 19 20
F2
B100
7

EN(H4DOTC)-95
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
•RHD model
EN-02323
B122
MANIFOLD
ABSOLUTE
PRESSURE
SENSOR
THROTTLE BODY
3 2
1
35
16 22
ECM
B136
E21
E3
B22
2
1
20 18 16
123
B122 B22E21
12
5 6 7 8
13 14 15 16
9 10 11 12
3 4
17 18 19 20
B136
1234
5 6 7 8
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

EN(H4DOTC)-96
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK IDLE SWITCH SIGNAL.
1) Turn the ignition switch to ON.
2) Operate the LED operation mode for
engine using Subaru Select Monitor.
N
O
TE:
• Subaru Select Monitor
For detailed operation procedure, refer to the
“LED OPERATION MODE FOR ENGINE”.
<Ref. to EN(H4DOTC)-33, Subaru Select Mon-
itor.>
Does the LED of {Idle Switch
Signal} come on?
Go to step 2. Check the throttle
position sensor cir-
cuit. <Ref. to
EN(H4DOTC)-
122, DTC P0121
THROTTLE/
PEDAL POSI-
TION SENSOR/
SWITCH “A” CIR-
CUIT RANGE/
PERFORMANCE,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
N
O
TE:
In this case, it is
not necessary to
inspect DTC
P0106.
2 CHECK ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check related
DTC.“List of Diag-
nostic Trouble
Code (DTC)” <Ref.
to EN(H4DOTC)-
74, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0106.
Go to step 3.
3 CHECK MANIFOLD ABSOLUTE PRESSURE
SENSOR CONDITION.
Is the manifold absolute pres-
sure sensor installation bolt
tightened securely?
Go to step 4. Tighten manifold
absolute pressure
sensor installation
bolt securely.
4 CHECK CONDITION OF THROTTLE BODY. Is the throttle body installation
bolt tightened securely?
Replace the mani-
fold absolute pres-
sure sensor. <Ref.
to FU(H4DOTC)-
36, Manifold Abso-
lute Pressure Sen-
sor.>
Tighten throttle
body installation
bolt securely.