SUBARU FORESTER 2004 Service Repair Manual

EN(H4SO)-163
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS BETWEEN EGR VALVE
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Detach the connector from EGR valve and
ECM.
3) Measure the resistance of harness
between EGR valve and ECM connector.
Connector & terminal
(B134) No. 18 — (E18) No. 6:
(B134) No. 17 — (E18) No. 1:
(B134) No. 16 — (E18) No. 4:
(B134) No. 15 — (E18) No. 3:Is the resistance less than 1
Ω?Go to step 7.Repair open circuit
in harness
between ECM and
EGR valve con-
nector.
7 CHECK HARNESS BETWEEN EGR VALVE
AND ECM CONNECTOR.
Measure the resistance of harness between
EGR valve and chassis ground.
Connector & terminal
(B134) No. 15 — Chassis ground:
(B134) No. 16 — Chassis ground:
(B134) No. 17 — Chassis ground:
(B134) No. 18 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 8.Repair short circuit
in harness
between main
relay and EGR
valve connector.
8 CHECK POOR CONTACT.
Check that the poor contact of ECM and EGR
valve connector.Is there poor contact of ECM
and EGR valve connector?Repair the poor
contact portion of
ECM and EGR
valve connector.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a spec-
ified condition at
this time. Step Check Yes No

EN(H4SO)-164
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AN:DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK
1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Engine stalls
 Idle mixture is out of specifications.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)-44, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-37, OPERATION, Inspec-
tion Mode.>.
WIRING DIAGRAM:
EN-02391
B18
T6
3412
56
B47F44
12345678
T5B136
B137 B135
BATTERY
REAR
OXYGEN
SENSORFRONT OXYGEN
(A/F) SENSORMAIN RELAYSBF-5
B61 F44
B47
T6
T5
B19B18 1 2 3 5 6
4
E
7
B122
B19B14D15C43
4
2B23C13C22C6C17
1
8
1
B135ECM
B136 B :
C :
B137 D :
5
2
84
3923 20 211011
221617
24
2512136
261915
14
1
7
18
4
1
53
2618 15 167891011
17 19
20121314
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21
LHD
LHD
RHD
RHD
4
1
B122
LHDLHD
RHDRHD
4
1 23
3
4
21
1234
3412
B122 : LHD
B122 : RHD
123456781234
B :C :
D :

EN(H4SO)-165
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0420.Go to step 2.
2 CHECK EXHAUST SYSTEM.
Check for gas leaks or air suction caused by
loose or dislocated nuts and bolts, and open
hole at exhaust pipes.
NOTE:
Check the following positions.
 Between cylinder head and front exhaust
pipe
 Between front exhaust pipe and front cata-
lytic converter
 Between front catalytic converter and rear
catalytic converterIs there a fault in exhaust sys-
tem?Repair or replace
the exhaust sys-
tem. <Ref. to
EX(H4SO)-2, Gen-
eral Description.>Go to step 3.
3 CHECK CATALYTIC CONVERTER.Is there damage at rear face or
front face of catalytic con-
ver ter?Replace catalytic
converter. <Ref. to
EC(H4SO)-3,
Front Catalytic
Converter.>Go to step 4.
4 CHECK REAR OXYGEN SENSOR CIRCUIT
MALFUNCTION.
1) Disconnect the connector from rear oxygen
sensor and ECM.
2) Measure the resistance between rear oxy-
gen sensor connector and ECM connector.
Connector & terminal
(T6) No. 3 — (B135) No. 19:Is the resistance less than 1
Ω?Go to step 5.Repair battery
open circuit in har-
ness between
ECM and rear oxy-
gen sensor.
5 CHECK SHIELD WIRE.Is the shield wire opened? Repair the shield
wire.Contact the SUB-
ARU dealer.

EN(H4SO)-166
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AO:DTC P0458 EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-
TROL VALVE CIRCUIT LOW
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)-44, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-37, OPERATION, Inspec-
tion Mode.>.
WIRING DIAGRAM:
EN-02392
F44B61
PURGE CONTROL
SOLENOID VALVE
E4
B21
E2
B47
B47
34
12
56
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
BATTERY
MAIN RELAY
12
35
46
7
29
21
12
B134ECM
F44
12345678
E4
12
B134
1234567891011121314151617181920212223242526272829303132333435
LHDLHD
RHDRHD

EN(H4SO)-167
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 and
chassis ground.
Connector & terminal
(B134) No. 29 (+) — Chassis ground (
−):Is the voltage more than 10 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. Contact
the SUBARU
dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.Go to step 2.
2 CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from purge con-
trol solenoid valve and ECM.
3) Measure the resistance of harness
between purge control solenoid valve connec-
tor and engine ground.
Connector & terminal
(E4) No. 2 — Engine ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
ECM and purge
control solenoid
valve connector.
3 CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
Measure the resistance of harness between
ECM and purge control solenoid valve of har-
ness connector.
Connector & terminal
(B134) No. 29 — (E4) No. 2:Is the resistance less than 1
Ω?Go to step 4.Repair open circuit
in harness
between ECM and
purge control sole-
noid valve connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and purge
control solenoid
valve connector
 Poor contact in
coupling connector
4 CHECK PURGE CONTROL SOLENOID
VALVE.
1) Remove the purge control solenoid valve.
2) Measure the resistance between purge
control solenoid valve terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 10 — 100 Ω? Go to step 5.Replace the purge
control solenoid
valve. <Ref. to
EC(H4SO)-9,
Purge Control
Solenoid Valve.>
5 CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE.
1) Turn the ignition switch to ON.
2) Measure the voltage between purge control
solenoid valve and engine ground.
Connector & terminal
(E4) No. 1 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 6.Repair open circuit
in harness
between main
relay and purge
control solenoid
valve connector.

EN(H4SO)-168
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK POOR CONTACT.
Check poor contact in purge control solenoid
valve connector.Is there poor contact in purge
control solenoid valve connec-
tor?Repair poor con-
tact in purge con-
trol solenoid valve
connector.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts. Step Check Yes No

EN(H4SO)-169
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AP:DTC P0459 EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-
TROL VALVE CIRCUIT HIGH
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)-44, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-37, OPERATION, Inspec-
tion Mode.>.
WIRING DIAGRAM:
EN-02392
F44B61
PURGE CONTROL
SOLENOID VALVE
E4
B21
E2
B47
B47
34
12
56
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
BATTERY
MAIN RELAY
12
35
46
7
29
21
12
B134ECM
F44
12345678
E4
12
B134
1234567891011121314151617181920212223242526272829303132333435
LHDLHD
RHDRHD

EN(H4SO)-170
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector at the
lower portion of instrument panel (on the
driver’s side).
3) Turn the ignition switch to ON.
4) While operating the purge control solenoid
valve, measure voltage between ECM and
chassis ground.
N
OTE:
Purge control solenoid valve operation can be
executed using Subaru Select Monitor. Refer to
“Compulsory Valve Operation Check Mode” for
procedures. <Ref. to EN(H4SO)-45, Compul-
sory Valve Operation Check Mode.>
Connector & terminal
(B134) No. 29 (+) — Chassis ground (
−):Is the voltage 0 — 10 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. In this
case, repair poor
contact in ECM
connector.
2 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 29 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 4.Go to step 3.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector. Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
<Ref. to
FU(H4SO)-44,
Engine Control
Module (ECM).>
4 CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from purge con-
trol solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 29 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and purge
control solenoid
valve connector.
After repair,
replace the ECM.
<Ref. to
FU(H4SO)-44,
Engine Control
Module (ECM).>Go to step 5.
5 CHECK PURGE CONTROL SOLENOID
VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge
control solenoid valve terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 1
Ω?Replace the purge
control solenoid
valve <Ref. to
EC(H4SO)-9,
Purge Control
Solenoid Valve.>
and ECM. <Ref. to
FU(H4SO)-44,
Engine Control
Module (ECM).>Go to step 6.
6 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
<Ref. to
FU(H4SO)-44,
Engine Control
Module (ECM).>

EN(H4SO)-171
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AQ:DTC P0461 FUEL LEVEL SENSOR CIRCUIT RANGE/PERFORMANCE
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)-44, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-37, OPERATION, Inspec-
tion Mode.>.
WIRING DIAGRAM:
R59R58
R57
R15
B38i3
B98R2
B10
C1 B9
25
3
5
i10 B :
i11 C :B135ECM
EE
E
IGNITION
SWITCH
SBF-4SBF-14
COMBINATION
METERSBF-1
B72
14
FUEL SUB
LEVEL SENSOR
FUEL SUB
METER UNIT
FUEL LEVEL
SENSOR1
2
BATTERY
B38
i3
B38
i320E2
B211528
LHD
LHDRHD
RHDLHD
LHDRHD
RHD
2
16
B38i3
LHD
LHDRHD
RHD
4 3
B99R3
B38i3
LHD
LHDRHD
RHD
16
5
B37i2
EN-02393
2
3
B135
B72
R15R59i10R58
3412
13
456212123456789101112131415161718192021222324252627282930
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21
219
32
1234 5610 11 12 13 14 15716
23 3019 20
22 26 27 28 29817
24 3118
25
i3
B99
12345678
i11
34 12 8567910
B37
34 12 8910 11
12 13 14 15 16 17 18 19 20 21 22 23 24567
B:
C:
B98
123
4
56
78
9
1011 12
1314 15 16
B21

EN(H4SO)-172
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0420.Replace the fuel
level sensor. <Ref.
to FU(H4SO)-57,
Fuel Level Sen-
sor.> and fuel sub
level sensor. <Ref.
to FU(H4SO)-58,
Fuel Sub Level
Sensor.>