Subaru Impreza 2004 User manual

FUJI HEAVY INDUSTRIES LTD. G1870GE3
2004 IMPREZA 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 SYSTEMS) FU(H4DOTC)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4DOTC)
INTAKE (INDUCTION) IN(H4DOTC)
MECHANICAL ME(H4DOTC)
EXHAUST EX(H4DOTC)
COOLING CO(H4DOTC)
LUBRICATION LU(H4DOTC)
SPEED CONTROL SYSTEMS SP(H4DOTC)
IGNITION IG(H4DOTC)
STARTING/CHARGING SYSTEMS SC(H4DOTC)
ENGINE (DIAGNOSTICS) EN(H4DOTC)(diag)

EN(H4DOTC)(diag)-81
ENGINE (DIAGNOSTICS)
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 SYS-
TEM PERFORMANCE (BANK 1)
•DTC DETECTING CONDITION:
•Immediately at fault recognition
•TROUBLE SYMPTOM:
•Engine stalls.
•Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
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)”. <Ref. to
EN(H4DOTC)(dia
g)-74, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1)Start the engine and let it idle.
2)Inspect the AVCS operating angle and oil
flow control solenoid valve duty output using
Subaru Select Monitor and 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(H4DOTC)(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 AVCS operating angle
more than approx. 0° and the
oil flow control solenoid valve
duty output more than approx.
10%?
A temporary mal-
function. Conduct
the following to
clean the oil pas-
sage.
Replace the
engine oil and idle
the engine for 5
minutes, then
replace the oil filter
and engine oil.
Inspect the follow-
ing items and
repair or replace if
necessary.
•Engine oil
(amount, con-
tamination)
•Oil pipe (clog)
•Oil flow con-
trol solenoid
valve (clog or
contamination
in oil passage,
settling at
spring, stuck at
valve)
•Intake cam-
shaft (sludge,
damage at
camshaft)
•Timing belt
(timing mark
aligning)

EN(H4DOTC)(diag)-82
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
B: DTC P0021 “A”CAMSHAFT POSITION-TIMING OVER-ADVANCED OR SYS-
TEM PERFORMANCE (BANK 2)
•DTC DETECTING CONDITION:
•Immediately at fault recognition
•TROUBLE SYMPTOM:
•Engine stalls.
•Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
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)”. <Ref. to
EN(H4DOTC)(dia
g)-74, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1)Start the engine and let it idle.
2)Inspect the AVCS operating angle and oil
flow control solenoid valve duty output using
Subaru Select Monitor and 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(H4DOTC)(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 AVCS operating angle
more than approx. 0° and the
oil flow control solenoid valve
duty output more than approx.
10%?
A temporary mal-
function. Conduct
the following to
clean the oil pas-
sage.
Replace the
engine oil and idle
the engine for 5
minutes, then
replace the oil filter
and engine oil.
Inspect the follow-
ing items and
repair or replace if
necessary.
•Engine oil
(amount, con-
tamination)
•Oil pipe (clog)
•Oil flow con-
trol solenoid
valve (clog or
contamination
in oil passage,
settling at
spring, stuck at
valve)
•Intake cam-
shaft (sludge,
damage at
camshaft)
•Timing belt
(timing mark
aligning)

EN(H4DOTC)(diag)-83
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
C: 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(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
EN-01299
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B61 F44
2LHD
RHD
LHD
RHD
B100
F2
F60
E3
123
RHD
RHD
8 9
4 5
19 29 18
ECM
B84
: LHD
: LHD
B22 : RHD
: RHD
2
4 1 3
B18
FRONT OXYGEN
(A/F) SENSOR
34
12
34
12
56
1234
5 6 7 8
1234
5678
9
10 11 12
13 14 15 16
B22
F60
F44
B47
B18
B84
12 78956
34
10 11 12 19 20 21
29 30 31
13 14 15 16 17
27 28
18
22 23 24 25 26
F2
LHDLHD
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-84
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
(B84) No. 5 —(B18) No. 1:
(B84) No. 4 —(B18) No. 1:
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
(B84) No. 19 —(B18) No. 4:
(B84) No. 29 —(B18) 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 —(B18) No. 2:
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)-44,
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(H4DOTC)-44,
Front Oxygen (A/
F) Sensor.>

EN(H4DOTC)(diag)-85
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
D: 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(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
EN-01299
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B61 F44
2LHD
RHD
LHD
RHD
B100
F2
F60
E3
123
RHD
RHD
8 9
4 5
19 29 18
ECM
B84
: LHD
: LHD
B22 : RHD
: RHD
2
4 1 3
B18
FRONT OXYGEN
(A/F) SENSOR
34
12
34
12
56
1234
5 6 7 8
1234
5678
9
10 11 12
13 14 15 16
B22
F60
F44
B47
B18
B84
12 78956
34
10 11 12 19 20 21
29 30 31
13 14 15 16 17
27 28
18
22 23 24 25 26
F2
LHDLHD
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-86
ENGINE (DIAGNOSTICS)
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
(B18) No. 2 (+) —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 connector
•Poor contact in
front oxygen (A/F)
sensor connector
•Poor contact in
main relay connec-
tor
2 CHECK GROUND CIRCUIT OF ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B84) No. 8 —Chassis ground:
(B84) No. 9 —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 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.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H4DOTC)(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 poor
contact in connec-
tor.
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 connec-
tor and chassis ground.
Connector & terminal
(B84) No. 4 (+) —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
(B84) No. 4 (+) —Chassis ground ( −
−−
−
):
Shake the ECM harness and
connector, while monitoring
value of voltage meter. Does
the voltage change?
Repair the poor
contact in ECM
connector.
Go to step 6.
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B84) No. 5 (+) —Chassis ground (
−
−−
−
):
Is the voltage less than 1 V? Go to step 8. Go to step 7.

EN(H4DOTC)(diag)-87
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B84) No. 5 (+) —Chassis ground (
−
−−
−
):
Shake the ECM harness and
connector, while monitoring
value of voltage meter. Does
the voltage change?
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)-44,
Front Oxygen (A/
F) Sensor.>
Step Check Yes No

EN(H4DOTC)(diag)-88
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
E: 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(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion 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
(B84) No. 4 (+) —Chassis ground (
−
−−
−
):
(B84) No. 5 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 8 V? Go to step 3. Go to step 2.
EN-01299
BATTERY
MAIN RELAY
SBF-5
B47
1
2
3
5
4
6
E
E
B61 F44
2LHD
RHD
LHD
RHD
B100
F2
F60
E3
123
RHD
RHD
8 9
4 5
19 29 18
ECM
B84
: LHD
: LHD
B22 : RHD
: RHD
2
4 1 3
B18
FRONT OXYGEN
(A/F) SENSOR
34
12
34
12
56
1234
5 6 7 8
1234
5678
9
10 11 12
13 14 15 16
B22
F60
F44
B47
B18
B84
12 78956
34
10 11 12 19 20 21
29 30 31
13 14 15 16 17
27 28
18
22 23 24 25 26
F2
LHDLHD
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-89
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(H4DOTC)(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(H4DOTC)-49,
Engine Control
Module (ECM).>
END
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B84) No. 4 (+) —Chassis ground (
−
−−
−
):
(B84) No. 5 (+) —Chassis ground (
−
−−
−
):
Shake the ECM harness and
connector, while monitoring
value of voltage meter. Does
the voltage change?
Repair the battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
END
Step Check Yes No

EN(H4DOTC)(diag)-90
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
F: DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (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)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
EN-01300
BATTERY
MAIN RELAY
B47
1
2
3
5
4
6
E
E
B61 F44
2LHD
RHD
LHD
RHD
B100
F2
F60
E3
123
RHD
LHD
RHD
B260 *1
*2
B259
1
LHD
LHD
: LHD
: LHD
(RHD)
(LHD)
B22
B83
: RHD
: RHD
34
12
56
1234
5 6 7 8
1234
5678
9
10 11 12
13 14 15 16
B22
B135
B137
F60
F44
B83
B47
B19
B84
12 78956
34
10 11 12 19 20 21
29 30 31
13 14 15 16 17
27 28
18
22 23 24 25 26
*3
*5 *4
*6
B19
REAR
OXYGEN SENSOR
E8 E9
D13
B17 B26 B19
ECM
B137
B84
D :
B135
B :
E :
RHDRHD
LHD
12 3 4 5 6
56 78
21 94 3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
12 7
89
56
34
10 11 12
19 20 21
13 14 15 16
17 18 22 23 24
LHD : 2
RHD : 4
LHD : 6
RHD : 1
*1
*2
12
B259
123
456
LHD : 2
RHD : 1
LHD : 1
RHD : 2
LHD : 3
RHD : 4
LHD : 4
RHD : 3
*3
*4
*5
*6
F2
(LHD)
(RHD)
21
4 3
12
3 4
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-91
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
(B84) No. 8 —Chassis ground:
(B84) No. 9 —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 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 FOR ENGINE”.
<Ref. to EN(H4DOTC)(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.
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 connec-
tor and chassis ground.
Connector & terminal
(B137) No. 13 (+) —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
(B137) No. 13 (+) —Chassis ground ( −
−−
−
):
Shake the ECM harness and
connector, while monitoring
value of voltage meter. Does
the voltage change?
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 connec-
tor and chassis ground.
Connector & terminal
(B137) No. 13 (+) —Chassis ground (
−
−−
−
):
Is the voltage less than 1 V? Replace the ECM.
<Ref. to
FU(H4DOTC)-49,
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(H4DOTC)-49,
Engine Control
Module (ECM).>

EN(H4DOTC)(diag)-92
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
LHD model
(B19) No. 2 (+) —Chassis ground (
−
−−
−
):
RHD model
(B19) 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)-46,
Rear Oxygen Sen-
sor.>
Step Check Yes No

EN(H4DOTC)(diag)-93
ENGINE (DIAGNOSTICS)
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)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
Step Check Yes No
1 CHECK INPUT SIGNAL FOR ECM.
1)Turn the ignition switch to OFF.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 13 (+) —Chassis ground (
−
−−
−
):
Is the voltage more than 8 V? Go to step 2. Go to step 3.
EN-01300
BATTERY
MAIN RELAY
B47
1
2
3
5
4
6
E
E
B61 F44
2LHD
RHD
LHD
RHD
B100
F2
F60
E3
123
RHD
LHD
RHD
B260 *1
*2
B259
1
LHD
LHD
: LHD
: LHD
(RHD)
(LHD)
B22
B83
: RHD
: RHD
34
12
56
1234
5 6 7 8
1234
5678
9
10 11 12
13 14 15 16
B22
B135
B137
F60
F44
B83
B47
B19
B84
12 78956
34
10 11 12 19 20 21
29 30 31
13 14 15 16 17
27 28
18
22 23 24 25 26
*3
*5 *4
*6
B19
REAR
OXYGEN SENSOR
E8 E9
D13
B17 B26 B19
ECM
B137
B84
D :
B135
B :
E :
RHDRHD
LHD
12 3 4 5 6
56 78
21 94 3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
12 7
89
56
34
10 11 12
19 20 21
13 14 15 16
17 18 22 23 24
LHD : 2
RHD : 4
LHD : 6
RHD : 1
*1
*2
12
B259
123
456
LHD : 2
RHD : 1
LHD : 1
RHD : 2
LHD : 3
RHD : 4
LHD : 4
RHD : 3
*3
*4
*5
*6
F2
(LHD)
(RHD)
21
4 3
12
3 4
34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-94
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 CHECK CURRENT DATA.
1)Repair the battery short circuit in harness
between ECM and rear oxygen sensor connec-
tor.
2)Turn the ignition switch to ON.
3)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(H4DOTC)(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(H4DOTC)-49,
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
Step Check Yes No

EN(H4DOTC)(diag)-95
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
H: DTC P0068 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE
CIRCUIT 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)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
•LHD model
EN-02560
B83
MANIFOLD
ABSOLUTE
PRESSURE
SENSOR
THROTTLE BODY
3 2
1
19
9 8
ECMB135
E21
E2
F61
1
6
20 18 16
F2
B100
4
17 16
1 2 3
F61
E21
12
5 6 7 8
13 14 15 16
9 10 11 12
3 4
17 18 19 20
B135
56 78
21 9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
F2
B83
123
456 34
12 89
10 11
12 13 14 15 16 17 18 19 20 21 22 23 24
56 7

EN(H4DOTC)(diag)-96
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
•RHD model
EN-01302
B83
MANIFOLD
ABSOLUTE
PRESSURE
SENSOR
THROTTLE BODY
3 2
1
19
9 8
ECM
B135
E21
E2
B21
3
1
20 18 16
123
B83 B21E21
1 2 3 4 5 6 1 2
5 6 7 8
13 14 15 16
9 10 11 12
3 4
17 18 19 20
B135
56 78
21 9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21

EN(H4DOTC)(diag)-97
ENGINE (DIAGNOSTICS)
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)(diag)-32, Subaru
Select Monitor.>
Does the LED of {Idle Switch
Signal} come on?
Go to step 2. Check the throttle
position sensor cir-
cuit. <Ref. to
EN(H4DOTC)(dia
g)-121, DTC
P0121 THROT-
TLE/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? Inspect the rele-
vant DTC. “List of
Diagnostic Trou-
ble Code (DTC)”.
<Ref. to
EN(H4DOTC)(dia
g)-74, List of Diag-
nostic Trouble
Code (DTC).>
N
O
TE:
In this case, it is
not necessary to
inspect DTC
P0106.
Go to step 3.
3 CHECK CONDITION OF MANIFOLD ABSO-
LUTE PRESSURE SENSOR.
Is the manifold absolute pres-
sure sensor installation bolt
tightened securely?
Go to step 4. Tighten the mani-
fold absolute pres-
sure 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)-
35, Manifold Abso-
lute Pressure Sen-
sor.>
Tighten the throttle
body installation
bolt securely.

EN(H4DOTC)(diag)-98
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
I: DTC P0101 MASS OR VOLUME AIR FLOW CIRCUIT RANGE/PERFOR-
MANCE
•DTC DETECTING CONDITION:
•Two consecutive driving cycles with fault
•TROUBLE SYMPTOM:
•Erroneous idling
•Engine stalls.
•Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-39, Inspec-
tion Mode.>.
•WIRING DIAGRAM:
EN-01303
B83
B3 B135
56 78
21 9
4
3
10
24
22 23 25
11 12 13 14 15
26 27 28
16 17 18 19
20 21
BATTERY
E
B61 F44
8LHD
RHD
LHD
RHD
B83
1
B3
MASS AIR FLOW AND INTAKE
AIR TEMPERATURE SENSOR
ECM
B135
B :
B136
C :
SBF-5
12 3 4534
12
56
1 2 3 4 5 6
B136B47
1
2
*
*
(LHD)
(RHD)
2 4 3 5
C7
B27
C13
B19
C8
LHD : 3
RHD : 2
LHD : 6
RHD : 1
*1
*2
F44
1234
5 6 7 8
123
89
10
4
11 12
13 14 15 16
56
7
17
123
4 5 6
MAIN RELAY
B47
1
2
3
5
4
6

EN(H4DOTC)(diag)-99
ENGINE (DIAGNOSTICS)
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)”. <Ref. to
EN(H4DOTC)(dia
g)-74, List of Diag-
nostic Trouble
Code (DTC).>
N
O
TE:
In this case, it is
not necessary to
inspect DTC
P0101.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4DOTC)-34,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>