SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-148
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AE:DTC P0171 SYSTEM TOO LEAN (BANK 1)
NOTE:
For diagnostic procedure, refer to DTC P0172. (BANK 1), 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)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0139.Replace the rear
oxygen sensor.
FU(H4DOTC)-47,
Rear Oxygen Sen-
sor.>

EN(H4DOTC)-149
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AF:DTC P0172 SYSTEM TOO RICH (BANK 1)
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 ERATION, Clear Memory Mode.> and Inspection Mode .
Step Check Yes No
1 CHECK EXHAUST SYSTEM.Are there holes or looseness of
the bolts on exhaust system?Repair exhaust
system.Go to step 2.
2 CHECK AIR INTAKE SYSTEM.Are there holes, loose bolts or
disconnection of hose on air
intake system?Repair air intake
system.Go to step 3.
3 CHECK FUEL PRESSURE.
Warning:
 Place “NO FIRE” signs near the working
area.
 Be careful not to spill fuel.
1) Release the fuel pressure.
(1) Disconnect the connector from fuel
pump relay.
(2) Start the engine and run it until it stalls.
(3) After the engine stalls, crank it for five
more seconds.
(4) Turn the ignition switch to OFF.
2) Connect the connector to fuel pump relay.
3) Disconnect the fuel delivery hose from fuel
filter, and connect the fuel pressure gauge.
4) Install the fuel filler cap.
5) Start the engine and idle while gear posi-
tion is neutral.
6) Measure the fuel pressure while discon-
necting pressure regulator vacuum hose from
intake manifold.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
N
OTE:
If fuel pressure does not increase, squeeze the
fuel return hose 2 to 3 times, then measure fuel
pressure again.Is measured value 284 — 314
kPa (2.9 — 3.2 kg/cm
2, 41 —
46 psi)?Go to step 4.Repair the follow-
ing items.
Fuel pressure is
too high:
 Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
 Improper fuel
pump discharge
 Clogged fuel
supply line

EN(H4DOTC)-150
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
4 CHECK FUEL PRESSURE.
After connecting the pressure regulator vac-
uum hose, measure fuel pressure.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
N
OTE:
 If fuel pressure does not increase, squeeze
fuel return hose 2 to 3 times, then measure
fuel pressure again.
 If out of specification as measured at this
step, check or replace pressure regulator and
pressure regulator vacuum hose.Is measured value 206 — 235
kPa (2.1 — 2.4 kg/cm
2, 30 —
34 psi)?Go to step 5.Repair the follow-
ing items.
Fuel pressure is
too high:
 Faulty pres-
sure regulator
 Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
 Faulty pres-
sure regulator
 Improper fuel
pump discharge
 Clogged fuel
supply line
5 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm-up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or the OBD-II general scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is engine coolant temperature
more than 60°C (140°F)?Go to step 6.Replace the
engine coolant
temperature sen-
sor. FU(H4DOTC)-29,
Engine Coolant
Temperature Sen-
sor.>
6 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start and warm-up the engine until engine
coolant temperature is greater than 60°C
(140°F).
2) Place the shift lever in neutral position.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Read the data of mass air flow and intake
air temperature sensor signal using Subaru
Select Monitor or the OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 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 measured value within
the following?
Ignition ON: 73.3 — 106.6 kPa
(550 — 800 mmHg, 21.65 —
31.50 inHg)
Idling: 24.0 — 41.3 kPa (180 —
310 mmHg, 7.09 — 12.20
inHg)Go to step 7.Replace the mass
air flow and intake
air temperature
sensor. FU(H4DOTC)-35,
Mass Air Flow and
Intake Air Temper-
ature Sensor.> Step Check Yes No

EN(H4DOTC)-151
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start and warm-up the engine until engine
coolant temperature is greater than 60°C
(140°F).
2) Place the shift lever in neutral position.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Open the hood.
6) Measure the ambient temperature.
7) Read the data of mass air flow and intake
air temperature sensor signal using Subaru
Select Monitor or the OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Subtract the ambient tempera-
ture from intake air tempera-
ture, and is the value from
−10°C (14°F) to 50°C (122°F)?Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.Check mass air
flow and intake air
temperature sen-
sor. FU(H4DOTC)-35,
Mass Air Flow and
Intake Air Temper-
ature Sensor.> Step Check Yes No

EN(H4DOTC)-152
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AG:DTC P0230 FUEL PUMP PRIMARY CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
LHD model
EN-02316
F44
B135B137
B46R122
EE
M
RHDRHD 10 7
6
FUEL PUMP
RELAY
FUEL PUMP
CONTROL MODULE
FUEL
PUMP
SBF-5
B61
B46
R122
B135 B :
B137 D :
R15
R57
R58
R3
ECM
B99
B99R58
B99
R3
F44
7LHD LHDBATTERY
1
1
4
D28
B27
123456783412123456789102356
24
1
4
9
85
14
7
8
R15
567
82 1
94 310
24 22 23 2511 12 13 14 15
26 27
2816 17 18 19
20 21
29 30 31 32 33 34 35567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
123
45678
B :
D :

EN(H4DOTC)-153
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
RHD model
EN-02317
B97
B135B137
R122
EE
M
10 7
6
FUEL PUMP
RELAY
FUEL PUMP
CONTROL MODULE
FUEL
PUMP
SBF-5
B46
R122
B135 B :
B137 D :
R15
R57
R58
R2
ECM
B98
B98R58
B97
R1
BATTERY
8
1
4
D28
B27
123456783412123456789102356
24
1
4
9
85
14
14
15
219
32
1234
5610 11 12 13 14 15716
23 3019 20
22 26 27 28 29817
24 3118
25
567
82 1
94 310
24 22 23 2511 12 13 14 15
26 27
2816 17 18 19
20 21
29 30 31 32 33 34 35567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
B46R15

EN(H4DOTC)-154
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK POWER SUPPLY CIRCUIT TO FUEL
PUMP CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel pump
control unit.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pump
control unit and chassis ground.
Connector & terminal
(R122) No. 10 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 2.Repair the power
supply circuit.
N
OTE:
In this case repair
the following:
 Open or ground
short circuit in har-
ness between fuel
pump relay and
fuel pump control
unit.
 Poor contact in
fuel pump control
unit connector.
 Poor contact in
fuel pump relay
connector.
2 CHECK GROUND CIRCUIT OF FUEL PUMP
CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between fuel pump control unit and chassis
ground.
Connector & terminal
(R122) No. 5 — Chassis ground:Is the resistance less than 5
Ω?Go to step 3.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit
between fuel pump
control unit and
chassis ground.
 Poor contact in
fuel pump control
unit connector.
3 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from fuel pump.
2) Measure the resistance of harness
between fuel pump control unit and fuel pump
connector.
Connector & terminal
(R122) No. 7 — (R58) No. 1:
(R122) No. 6 — (R58) No. 4:Is the resistance less than 1
Ω?Go to step 4.Repair open circuit
between fuel pump
control unit and
fuel pump.
4 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
Measure the resistance of harness between
fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 7 — Chassis ground:
(R122) No. 6 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit
between fuel pump
control unit and
fuel pump.

EN(H4DOTC)-155
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
5 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance in harness
between fuel pump control unit and ECM con-
nector.
Connector & terminal
(R122) No. 8 — (B135) No. 27:
(R122) No. 9 — (B137) No. 28:Is the resistance less than 1
Ω?Go to step 6.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit
between fuel pump
control unit and
ECM.
 Poor contact in
fuel pump control
unit and ECM con-
nector
6 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND ECM CONNECTOR.
Measure the resistance of harness between
fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 8 — Chassis ground:
(R122) No. 9 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair the ground
short circuit
between fuel pump
control unit and
ECM.
7 CHECK POOR CONTACT.
Check poor contact in ECM and fuel pump
control unit connector.Is there poor contact in ECM
and fuel pump control unit con-
nector?Repair the poor
contact in ECM
and fuel pump
control unit.Go to step 8.
8 CHECK EXPERIENCE OF OUT OF GAS.Have the vehicle been out of
gas before?Complete the
diagnosis.
N
OTE:
DTC may be re-
corded due to the
idle running of fuel
pump at out of gas.Replace the fuel
pump control unit.
FU(H4DOTC)-53,
Fuel Pump Control
Unit.> Step Check Yes No

EN(H4DOTC)-156
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AH:DTC P0244 TURBO/SUPER CHARGER WASTEGATE SOLENOID “A”
RANGE/PERFORMANCE
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 ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02328
MAIN RELAY
B47 1 2 3 5 4 6
BATTERY
E
B61F44
F44
B47
B134
B127
B134
B127
WASTGATE
CONTROL SOLENOID
VALVEECM
32 1 2
7LHD
RHD
LHD
RHDSBF-5
12345678
3412
56
12
56 7
82 1
94 310
24 22 23 25 11 12 13 14 15
26 27
2816 17
18 19 20 21
33 34 29
32 30 31

EN(H4DOTC)-157
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)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0244.Replace the
wastegate control
solenoid valve.
FU(H4DOTC)-44,
Wastegate Con-
trol Solenoid Valve
Assembly.>