2004 SUBARU FORESTER oxygen

EN(H4SO)-227
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BT:DTC P1134 A/F SENSOR MICRO-COMPUTER PROBLEM
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 tion Mode.>.
WIRING DIAGRAM:
EN-02384
B18
3412
56
B47F44
12345678
B136B135
1234
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
EE
B47
B18
6
4
5
3
2
1
B23 C13
C22C6 C17
C16
C5
8
B:
C:B135
B136
B21
E2 ECMBATTERY
B61F44
7
FRONT OXYGEN
(A/F) SENSOR MAIN RELAY
567
82 1
94
310
24
22 23251112131415
26 27
281617181920 21
5
2
84
3923 20 211011
221617
24
2512136
261915
14
1
7
18
LHDLHD
RHDRHD
4
3
1 2
B: C:

EN(H4SO)-229
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BU:DTC P1137 O2 SENSOR CIRCUIT (LAMBDA=1) (BANK 1 SENSOR 1)
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 tion Mode.>.
WIRING DIAGRAM:
EN-02384
B18
3412
56
B47F44
12345678
B136B135
1234
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
EE
B47
B18
6
4
5
3
2
1
B23 C13
C22C6 C17
C16
C5
8
B:
C:B135
B136
B21
E2 ECMBATTERY
B61F44
7
FRONT OXYGEN
(A/F) SENSOR MAIN RELAY
567
82 1
94
310
24
22 23251112131415
26 27
281617181920 21
5
2
84
3923 20 211011
221617
24
2512136
261915
14
1
7
18
LHDLHD
RHDRHD
4
3
1 2
B: C:

EN(H4SO)-230
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 DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
1) Start the engine.
2) While observing the Subaru Select Monitor
or OBD-II general scan tool screen, warm-up
the engine until coolant temperature is above
70°C (160°F).
If the engine is already warmed-up, operate at
idle speed for at least 1 minute.
3) Read the data of front oxygen (A/F) sensor
signal at idling 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”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage 0.85 — 1.15 V? Go to step 3.Go to step 4.
3 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
Race the engine at speeds from idling to 5,000
rpm for a total of 5 cycles.
N
OTE:
 Normally the air fuel ratio be rich at racing.
 To increase engine speed to 5,000 rpm,
slowly depress accelerator pedal, taking
approximately 5 seconds, and quickly release
accelerator pedal to decrease engine speed.Is the voltage more than 1.1 V? Go to step 6.Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor connector.
3) Measure the resistance between ECM and
front oxygen (A/F) sensor.
Connector & terminal
(B136) No. 13 — (B18) No. 1:
(B136) No. 22 — (B18) No. 2:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
front oxygen (A/F)
sensor.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit
between ECM and
front oxygen (A/F)
sensor.

EN(H4SO)-231
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
N
OTE:
Check the following items:
 Loose installation of portions
 Damage (crack, hole etc.) of parts
 Looseness of front oxygen (A/F) sensor
 Looseness and ill fitting of parts between
front oxygen (A/F) sensor and rear oxygen
sensorIs there a fault in exhaust sys-
tem?Repair or replace
the faulty par t.Replace the front
oxygen (A/F) sen-
sor. FU(H4SO)-40,
Front Oxygen (A/
F) Sensor.> Step Check Yes No

EN(H4SO)-255
ENGINE (DIAGNOSTIC)
General Diagnostic Table
20.General Diagnostic Table
A: INSPECTION
1. ENGINE
NOTE:
Malfunction of parts other than those listed is also possible. eral.>
Symptom Problem parts
1. Engine stalls during idling.1) Idle air control solenoid valve
2) Manifold absolute pressure sensor
3) Intake air temperature sensor
4) Ignition parts (*1)
5) Engine coolant temperature sensor (*2)
6) Crankshaft position sensor (*3)
7) Camshaft position sensor (*3)
8) Fuel injection parts (*4)
2. Rough idling1) Idle air control solenoid valve
2) Manifold absolute pressure sensor
3) Intake air temperature sensor
4) Engine coolant temperature sensor (*2)
5) Ignition parts (*1)
6) Air intake system (*5)
7) Fuel injection parts (*4)
8) Throttle position sensor
9) Crankshaft position sensor (*3)
10) Camshaft position sensor (*3)
11) Oxygen sensor
12) Fuel pump and fuel pump relay
3. Engine does not return to idle.1) Idle air control solenoid valve
2) Engine coolant temperature sensor
3) Accelerator cable (*6)
4) Throttle position sensor
5) Manifold absolute pressure sensor
6) Intake air temperature sensor
4. Poor acceleration1) Manifold absolute pressure sensor
2) Intake air temperature sensor
3) Throttle position sensor
4) Fuel injection parts (*4)
5) Fuel pump and fuel pump relay
6) Engine coolant temperature sensor (*2)
7) Crankshaft position sensor (*3)
8) Camshaft position sensor (*3)
9) A/C switch and A/C cut relay
10) Engine torque control signal circuit
11) Ignition parts (*1)
5. Engine stalls or engine sags or hesitates at
acceleration.1) Manifold absolute pressure sensor
2) Intake air temperature sensor
3) Engine coolant temperature sensor (*2)
4) Crankshaft position sensor (*3)
5) Camshaft position sensor (*3)
6) Purge control solenoid valve
7) Fuel injection parts (*4)
8) Throttle position sensor
9) Fuel pump and fuel pump relay

FUEL INJECTION (FUEL SYSTEM)
FU(H4DOTC)
Page
1. General Description ....................................................................................2
2. Throttle Body .............................................................................................13
3. Intake Manifold ..........................................................................................14
4. Engine Coolant Temperature Sensor........................................................29
5. Crankshaft Position Sensor.......................................................................30
6. Camshaft Position Sensor.........................................................................31
7. AVCS Camshaft Position Sensor ..............................................................32
8. Knock Sensor ............................................................................................33
9. Throttle Position Sensor ............................................................................34
10. Mass Air Flow and Intake Air Temperature Sensor ..................................35
11. Manifold Absolute Pressure Sensor ..........................................................36
12. Idle Air Control Solenoid Valve .................................................................37
13. Fuel Injector ..............................................................................................38
14. Tumble Generator Valve Assembly ..........................................................42
15. Tumble Generator Valve Actuator.............................................................43
16. Wastegate Control Solenoid Valve Assembly ...........................................44
17. Front Oxygen (A/F) Sensor .......................................................................45
18. Rear Oxygen Sensor.................................................................................47
19. Exhaust Temperature Sensor ...................................................................49
20. Engine Control Module (ECM) ..................................................................50
21. Main Relay ................................................................................................51
22. Fuel Pump Relay.......................................................................................52
23. Fuel Pump Control Unit .............................................................................53
24. Fuel ...........................................................................................................54
25. Fuel Tank ..................................................................................................55
26. Fuel Filler Pipe ..........................................................................................58
27. Fuel Pump .................................................................................................62
28. Fuel Level Sensor .....................................................................................64
29. Fuel Sub Level Sensor ..............................................................................65
30. Fuel Filter ..................................................................................................67
31. Fuel Cut Valve...........................................................................................68
32. Fuel Damper Valve ...................................................................................69
33. Fuel Delivery, Return and Evaporation Lines............................................70
34. Fuel System Trouble in General ...............................................................73

FU(H4DOTC)-45
FUEL INJECTION (FUEL SYSTEM)
Front Oxygen (A/F) Sensor
17.Front Oxygen (A/F) Sensor
A: REMOVAL
1) Disconnect the ground cable from battery.
2) Disconnect the connector from front oxygen (A/
F) sensor.
3) Disconnect the engine harness fixed by clip (A)
from bracket (B).
4) Remove the front right side wheel.
5) Lift-up the vehicle.
6) Remove the service hole cover.7) Apply SUBARU CRC or its equivalent to the
threaded portion of front oxygen (A/F) sensor, and
leave it for 1 minute or more.
SUBARU CRC (Part No. 004301003)
8) Remove the front oxygen (A/F) sensor.
CAUTION:
When removing the oxygen (A/F) sensor, wait
until the exhaust pipe cools, otherwise it will
damage the exhaust pipe.
B: INSTALLATION
1) Before installing the front oxygen (A/F) sensor,
apply anti-seize compound only to the threaded
portion of front oxygen (A/F) sensor to make next
removal easier.
Anti-seize compound:
SS-30 JET LUBE
CAUTION:
Never apply anti-seize compound to the protec-
tor of front oxygen (A/F) sensor.
2) Install the front oxygen (A/F) sensor.
Tightening torque:
30 N
⋅m (3.1 kgf-m, 22.1 ft-lb)
FU-00009
FU-02088
FU-00078
(A)(B)
FU-00079
FU-00080
FU-00080

FU(H4DOTC)-46
FUEL INJECTION (FUEL SYSTEM)
Front Oxygen (A/F) Sensor
3) Install the service hole cover.
4) Lower the vehicle.
5) Install the front right side wheel.
6) Connect the engine harness with clip (A) to
bracket (B).
7) Connect the connector of front oxygen (A/F)
sensor.
8) Connect the battery ground cable to battery.
FU-00079
FU-00078
(A)(B)
FU-02088
FU-00009