Subaru Impreza 2004 User manual

FUJI HEAVY INDUSTRIES LTD. G1870GE2
2004 IMPREZA 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)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SO)
INTAKE (INDUCTION) IN(H4SO)
MECHANICAL ME(H4SO)
EXHAUST EX(H4SO)
COOLING CO(H4SO)
LUBRICATION LU(H4SO)
SPEED CONTROL SYSTEMS SP(H4SO)
IGNITION IG(H4SO)
STARTING/CHARGING SYSTEMS SC(H4SO)
ENGINE (DIAGNOSTICS) EN(H4SO)(diag)
FUEL INJECTION (FUEL SYSTEMS) FU(H4SOw/oOBD)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SOw/oOBD)
INTAKE (INDUCTION) IN(H4SOw/oOBD)
MECHANICAL ME(H4SOw/oOBD)
EXHAUST EX(H4SOw/oOBD)
COOLING CO(H4SOw/oOBD)

2004 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 1
G1870GE2
LUBRICATION LU(H4SOw/oOBD)
SPEED CONTROL SYSTEMS SP(H4SOw/oOBD)
IGNITION IG(H4SOw/oOBD)
STARTING/CHARGING SYSTEMS SC(H4SOw/oOBD)
ENGINE (DIAGNOSTICS) EN(H4SOw/oOBD)
(diag)

EN(H4SO)(diag)-80
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
19.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)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, Inspection
Mode.>.
•WIRING DIAGRAM:
EN-01421
B18
34
12
56
B47 F44
1234
5 6 7 8
B136 B135
12
34
B22
1234
5678
9
10 11 12
13 14 15 16
SBF-5
E
E
B47
B18
6
4
5
3
2
1
4
3
1 2
B23 C13 C22
C6
C17
C16
C5
8
B:
C:
B135
B136
B22
E3
ECM
BATTERY
B61 F44
2
FRONT OXYGEN
(A/F) SENSOR
MAIN RELAY
567
8
21
9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
5
2
8
4
3
9
2320 21
10 11
22
16 17
24 25
12 13
6
26
19
15
14
1
7
18
LHD
LHD
RHD RHD

EN(H4SO)(diag)-81
ENGINE (DIAGNOSTICS)
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 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
(B136) No. 6 —(B18) No. 3:
(B136) No. 17 —(B18) No. 3:
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
(B136) No. 13 —(B18) No. 1:
(B136) No. 22 —(B18) No. 2:
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 MAIN RELAY
AND FRONT OXYGEN (A/F) SENSOR CON-
NECTOR.
Measure the resistance of harness between
main relay and front oxygen (A/F) sensor con-
nector.
Connector & terminal
(B47) No. 4 —(B18) No. 4:
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. 3 —No. 4:
Is the resistance less than 5
Ω?
Go to step 5. Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4SO)-43,
Front Oxygen (A/
F) Sensor.>
5 CHECK POOR CONTACT.
Check the poor contact in ECM and front oxy-
gen (A/F) sensor connector.
Is there poor contact in ECM 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)-43,
Front Oxygen (A/
F) Sensor.>

EN(H4SO)(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)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY. Does the Subaru Select Moni-
tor or OBD-II general scan tool
display DTC P0031 and P0037
at the same time?
Go to step 2. Go to step 5.
EN-01421
B18
34
12
56
B47 F44
1234
5 6 7 8
B136 B135
12
34
B22
1234
5678
9
10 11 12
13 14 15 16
SBF-5
E
E
B47
B18
6
4
5
3
2
1
4
3
1 2
B23 C13 C22
C6
C17
C16
C5
8
B:
C:
B135
B136
B22
E3
ECM
BATTERY
B61 F44
2
FRONT OXYGEN
(A/F) SENSOR
MAIN RELAY
567
8
21
9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
5
2
8
4
3
9
2320 21
10 11
22
16 17
24 25
12 13
6
26
19
15
14
1
7
18
LHD
LHD
RHD RHD

EN(H4SO)(diag)-83
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 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
(B18) No. 4 (+) —Engine ground (
−
−−
−
):
Is the voltage more than 10 V? Go to step 3. Repair power sup-
ply line.
N
O
TE:
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
3 CHECK GROUND CIRCUIT OF ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B136) No. 5 —Chassis ground:
(B136) No. 16 —Chassis ground:
Is the resistance less than 5
Ω?
Go to step 4. Repair harness
and connector.
N
O
TE:
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
4 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 the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
Is the current more than 0.2 A? Repair poor con-
tact in 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 5.
5 CHECK INPUT SIGNAL FROM ECM.
1)Start and idle the engine.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 6 (+) —Chassis ground (
−
−−
−
):
(B136) No. 17 (+) —Chassis ground (
−
−−
−
):
Is the voltage less than 1 V? Go to step 7. Go to step 6.
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 6 (+) —Chassis ground ( −
−−
−
):
(B136) No. 17 (+) —Chassis ground ( −
−−
−
):
Does the voltage change by
shaking the ECM harness and
connector?
Repair poor con-
tact in ECM con-
nector.
Go to step 7.
Step Check Yes No

EN(H4SO)(diag)-84
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 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. 3 —No. 4:
Is the resistance less than 10
Ω?
Repair harness
and connector.
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(H4SO)-50,
Fuel.>
Step Check Yes No

EN(H4SO)(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)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 6 (+) —Chassis ground (
−
−−
−
):
(B136) No. 17 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 8 V? Go to step 2. Go to step 3.
EN-01421
B18
34
12
56
B47 F44
1234
5 6 7 8
B136 B135
12
34
B22
1234
5678
9
10 11 12
13 14 15 16
SBF-5
E
E
B47
B18
6
4
5
3
2
1
4
3
1 2
B23 C13 C22
C6
C17
C16
C5
8
B:
C:
B135
B136
B22
E3
ECM
BATTERY
B61 F44
2
FRONT OXYGEN
(A/F) SENSOR
MAIN RELAY
567
8
21
9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
5
2
8
4
3
9
2320 21
10 11
22
16 17
24 25
12 13
6
26
19
15
14
1
7
18
LHD
LHD
RHD RHD

EN(H4SO)(diag)-86
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
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
the OBD-II general scan tool.
N
O
TE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
Is the current more than 2.3 A? Replace the ECM.
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
END
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 6 (+) —Chassis ground (
−
−−
−
):
(B136) No. 17 (+) —Chassis ground (
−
−−
−
):
Does the voltage change by
shaking the ECM harness and
connector?
Repair battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
END
Step Check Yes No

EN(H4SO)(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)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
EN-01422
BATTERY
B61 F44
2
B47
MAIN RELAY
1
2
3
5
4
6
F44
1234
5 6 7 8
C4
B14 B19 D15
C16
C5
REAR
OXYGEN SENSOR
ECM
1
4 3
2
8
B22
B83
B19
E3
B47
B22
1234
5678
9
10 11 12
13 14 15 16
34
5 6
12
1
B135
B:
D: B137
SBF-5
C: B136
B137
4
1
5
3
2
6
1815 16
7 8 9 10 11
17 19 20
12 13
14
B135
567
8
2
9
4
3
10
2422 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
B136
5
2
8
4
3
9
2320 21
10 11
22
16 17
24 25
12 13
6
26
19
15
14
1
7
18
*
E
E
1
B19
12
34
13
456
2
B83 : LHD
1 2 3 4
B83 : RHD
*LHD : 5
RHD : 4
LHD
RHD
LHD
RHD

EN(H4SO)(diag)-88
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 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
(B136) No. 5 —Chassis ground:
(B136) No. 16 —Chassis ground:
Is the resistance less than 5
Ω?
Go to step 2. Repair harness
and connector.
N
O
TE:
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
2 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of rear oxygen 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 the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
Is the current more than 0.2 A? Repair the con-
nector.
N
O
TE:
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 connec-
tor and chassis ground.
Connector & terminal
(B136) No. 4 (+) —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
(B136) No. 4 (+) —Chassis ground ( −
−−
−
):
Does the voltage change by
shaking the ECM harness and
connector?
Repair poor con-
tact in ECM con-
nector.
Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
1)Disconnect the connector from rear oxygen
sensor.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 4 (+) —Chassis ground ( −
−−
−
):
Is the voltage less than 1 V? Replace the ECM.
<Ref. to
FU(H4SO)-47,
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(H4SO)-47,
Engine Control
Module (ECM).>

EN(H4SO)(diag)-89
ENGINE (DIAGNOSTICS)
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
(B19) No. 2 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 10 V? Go to step 7. Repair power sup-
ply 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 harness
and connector.
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(H4SO)-45,
Rear Oxygen Sen-
sor.>
Step Check Yes No

EN(H4SO)(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)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
Step Check Yes No
1 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 4 (+) —Chassis ground ( −
−−
−
):
Is the voltage more than 8 V? Go to step 2. Go to step 3.
EN-01422
BATTERY
B61 F44
2
B47
MAIN RELAY
1
2
3
5
4
6
F44
1234
5 6 7 8
C4
B14 B19 D15
C16
C5
REAR
OXYGEN SENSOR
ECM
1
4 3
2
8
B22
B83
B19
E3
B47
B22
1234
5678
9
10 11 12
13 14 15 16
34
5 6
12
1
B135
B:
D: B137
SBF-5
C: B136
B137
4
1
5
3
2
6
1815 16
7 8 9 10 11
17 19 20
12 13
14
B135
567
8
2
9
4
3
10
2422 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
B136
5
2
8
4
3
9
2320 21
10 11
22
16 17
24 25
12 13
6
26
19
15
14
1
7
18
*
E
E
1
B19
12
34
13
456
2
B83 : LHD
1 2 3 4
B83 : RHD
*LHD : 5
RHD : 4
LHD
RHD
LHD
RHD

EN(H4SO)(diag)-91
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 CHECK CURRENT DATA.
1)Turn the ignition switch to OFF.
2)Repair the battery short circuit in harness
between ECM and rear oxygen sensor connec-
tor.
3)Turn the ignition switch to ON.
4)Read the data of rear oxygen sensor heater
current using Subaru Select Monitor or the
OBD-II general scan tool.
N
O
TE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
Is the current more than 7 A? Replace the ECM.
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
END
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM
connector?
Repair poor con-
tact in ECM con-
nector.
END
Step Check Yes No

EN(H4SO)(diag)-92
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
F: DTC P0066 AIR ASSISTED INJECTOR CONTROL CIRCUIT OR CIRCUIT
LOW
•DTC DETECTING CONDITION:
•Two consecutive driving cycles with fault
•TROUBLE SYMPTOM:
•Erroneous idling
•Engine stalls
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
EN-01423
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
24 25 26 27 28 29 30 31 32 33 34 35
1234
5678
9
10 11 12
13 14 15 16
34
5 6
12
1 2 1234
567 8
B134
B22
F44
B47
E42
B134 ECM
E42
E3
B22
1 7
12 1
2
AIR ASSIST
INJECTOR
SOLENOID
VALVE
BATTERY
SBF-5
2
B61 F44
MAIN RELAY
6
4
5
3
2
1
B47
E
LHD
RHD
LHD
RHD

EN(H4SO)(diag)-93
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn ignition switch to ON.
2)Measure voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 12 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 10 V? Repair poor con-
tact in ECM con-
nector.
Go to step 2.
2 CHECK POWER SUPPLY TO AIR ASSIST IN-
JECTOR SOLENOID VALVE.
1)Turn ignition switch to OFF.
2)Disconnect connector from air assist injector
solenoid valve.
3)Turn ignition switch to ON.
4)Measure voltage between air assist injector
solenoid valve and engine ground.
Connector & terminal
(E42) No. 2 (+) —Engine ground (
−
−−
−
):
Is the voltage more than 10 V? Go to step 3. Repair harness
and connector.
N
O
TE:
In this case, repair
the following:
•Open circuit in
harness between
air assist injector
solenoid valve and
main relay connec-
tor
•Poor contact in
coupling connector
3 CHECK HARNESS BETWEEN ECM AND AIR
ASSIST INJECTOR SOLENOID VALVE CON-
NECTOR.
1)Turn ignition switch to OFF.
2)Disconnect connector from ECM.
3)Measure resistance of harness between
ECM and air assist injector solenoid valve con-
nector.
Connector & terminal
(B134) No. 12—(E42) No. 1:
Is the resistance less than 1
Ω?
Go to step 4. Repair harness
and connector.
NOTE:
In this case, repair
the following:
•Open circuit in
harness between
ECM and air assist
injector solenoid
valve connector
•Poor contact in
coupling connector
4 CHECK HARNESS BETWEEN ECM AND AIR
ASSIST INJECTOR SOLENOID VALVE CON-
NECTOR.
Measure resistance of harness between ECM
and chassis ground.
Connector & terminal
(B134) No. 12—Chassis ground:
Is the resistance more than 1
MΩ?
Go to step 5. Repair ground
short circuit in har-
ness between
ECM and air assist
injector solenoid
valve connector.
5 CHECK POOR CONTACT.
Check poor contact in ECM and air assist
injector solenoid valve connectors.
Is there poor contact in ECM
and air assist injector solenoid
valve connectors?
Repair poor con-
tact in ECM and
air assist injector
solenoid valve
connectors.
Replace air assist
injector solenoid
valve. <Ref. to
FU(H4SO)-37, Air
Assist Injector
Solenoid Valve.>

EN(H4SO)(diag)-94
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
G: DTC P0067 AIR ASSISTED INJECTOR CONTROL CIRCUIT HIGH
•DTC DETECTING CONDITION:
•Two consecutive driving cycles with fault
•TROUBLE SYMPTOM:
•Erroneous idling
•Engine stalls
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
EN-01423
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
24 25 26 27 28 29 30 31 32 33 34 35
1234
5678
9
10 11 12
13 14 15 16
34
5 6
12
1 2 1234
567 8
B134
B22
F44
B47
E42
B134 ECM
E42
E3
B22
1 7
12 1
2
AIR ASSIST
INJECTOR
SOLENOID
VALVE
BATTERY
SBF-5
2
B61 F44
MAIN RELAY
6
4
5
3
2
1
B47
E
LHD
RHD
LHD
RHD

EN(H4SO)(diag)-95
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn ignition switch to ON.
2)Measure voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 12 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 10 V? Go to step 2. Go to step 3.
2 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn ignition switch to OFF.
2)Disconnect connector from air assist injector
solenoid valve.
3)Turn ignition switch to ON.
4)Measure voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 12 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and air assist
injector solenoid
valve connector.
After repair,
replace ECM.
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Replace air assist
injector solenoid
valve <Ref. to
FU(H4SO)-37, Air
Assist Injector
Solenoid Valve.>
and ECM <Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 12 (+) —Chassis ground (
−
−−
−
):
Does the voltage change by
shaking the ECM harness and
connector?
Repair battery
short circuit in har-
ness between
ECM and air assist
injector solenoid
valve connector.
After repair,
replace ECM.
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Contact with your
Subaru distributor
service.
N
O
TE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

EN(H4SO)(diag)-96
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
H: DTC P0107 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE
CIRCUIT LOW INPUT
•DTC DETECTING CONDITION:
•Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
•WIRING DIAGRAM:
19
3
15
MANIFOLD
ABSOLUTE
PRESSURE
SENSOR
9
15 12
B21
E2
1
2 3
E21
E21
ECM
B21
1 2
5 6 7 8
13 14 15 16
9 10 11 12
3 4
17 18 19 20
B135
B83
1
*
132
EN-01424
B135
567
8
21
9
4
3
10
2422 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
*LHD : 3
RHD : 2
13
456
2
B83 : LHD
1 2 3 4
B83 : RHD

EN(H4SO)(diag)-97
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of intake manifold absolute
pressure signal using Subaru Select Monitor or
OBD-II general scan tool.
N
O
TE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
Is the measured value less
than 13.3 kPa (100 mmHg,
3.94 inHg)?
Go to step 3. Go to step 2.
2 CHECK POOR CONTACT.
Check poor contact in ECM and manifold
absolute pressure sensor connector.
Is there poor contact in ECM or
manifold absolute pressure
sensor connector?
Repair poor con-
tact in ECM or
manifold absolute
pressure sensor
connector.
Even if malfunction
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time.
3 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 3 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 4.5 V? Go to step 5. Go to step 4.
4 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 3 (+) —Chassis ground (
−
−−
−
):
Does the voltage change by
shaking the ECM harness and
connector?
Repair poor con-
tact in ECM con-
nector.
Contact with SUB-
ARU distributor
service.
N
O
TE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.
5 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B135) No. 15 (+) —Chassis ground (
−
−−
−
):
Is the voltage less than 0.2 V? Go to step 7. Go to step 6.
6 CHECK INPUT SIGNAL FOR ECM. (USING
SUBARU SELECT MONITOR)
Read the data of atmospheric absolute pres-
sure signal using Subaru Select Monitor.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
Is the measured value more
than 13.3 kPa (100 mmHg,
3.94 inHg) by shaking the har-
ness and connector of ECM?
Repair poor con-
tact in ECM con-
nector.
Go to step 7.