2004 SUBARU FORESTER display

EN(H4SO)-138
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AA:DTC P0171 SYSTEM TOO LEAN (BANK 1)
Refer to DTC P0172 for diagnostic procedure. (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 DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0139.Replace the rear
oxygen sensor.
FU(H4SO)-42,
Rear Oxygen Sen-
sor.>

EN(H4SO)-143
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).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0301,
P0302, P0303 and
P0304.Go to step 2.
2 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground on faulty cylinders.
Connector & terminal
#1 (B134) No. 34 (+) — Chassis ground (
−):
#2 (B134) No. 23 (+) — Chassis ground (
−):
#3 (B134) No. 22 (+) — Chassis ground (
−):
#4 (B134) No. 8 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 7.Go to step 3.
3 CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinder.
3) Measure the voltage between ECM con-
nector and engine ground on faulty cylinders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#4 (E17) No. 1 — Engine ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between fuel
injector and ECM
connector.
4 CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
Measure the resistance of harness connector
between ECM connector and fuel injector on
faulty cylinders.
Connector & terminal
#1 (B134) No. 34 — (E5) No. 1:
#2 (B134) No. 23 — (E16) No. 1:
#3 (B134) No. 22 — (E6) No. 1:
#4 (B134) No. 8 — (E17) No. 1:Is the resistance less than 1
Ω?Go to step 5.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and fuel
injector connector
 Poor contact in
coupling connector
5 CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 5 — 20 Ω? Go to step 6.Replace the faulty
fuel injector. to FU(H4SO)-35,
Fuel Injector.>

EN(H4SO)-146
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
16 CHECK MISFIRE SYMPTOM.
1) Turn the ignition switch to ON.
2) READ DTC.
 Subaru Select Monitor
tor.>
 OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
N
OTE:
Perform diagnosis according to the items listed
below.Does the Subaru Select Moni-
tor or OBD-II general scan tool
indicate a DTC?Go to step 21.Go to step 17.
17 CHECK ANY OTHER DTC ON DISPLAY.Is DTC P0301 and P0302 dis-
played?Go to step 22.Go to step 18.
18 CHECK ANY OTHER DTC ON DISPLAY.Is DTC P0303 and P0304 dis-
played?Go to step 23.Go to step 19.
19 CHECK ANY OTHER DTC ON DISPLAY.Is DTC P0301 and P0303 dis-
played?Go to step 24.Go to step 20.
20 CHECK ANY OTHER DTC ON DISPLAY.Is DTC P0302 and P0304 dis-
played?Go to step 25.Go to step 26.
21 ONLY ONE CYLINDER.Is there a fault in that cylinder? Repair or replace
the faulty par t.
N
OTE:
Check the follow-
ing items:
 Spark plug
 Spark plug cord
 Fuel injector
 Compression
ratioGo to DTC P0171.
EN(H4SO)-138,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
22 GROUP OF #1 AND #2 CYLINDERS.Are there faults in #1 and #2
cylinders?Repair or replace
the faulty par t.
N
OTE:
 Check the fol-
lowing items:
 Spark plug
 Fuel injector
 Ignition coil
 Compres-
sion ratio
 If no abnormal is
discovered, check
for “IGNITION
CONTROL SYS-
TEM” of #1 and #2
cylinders side.
EN(H4SO)-64,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Fa il u r e. >Go to DTC P0171.
EN(H4SO)-138,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).> Step Check Yes No

EN(H4SO)-155
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 CONDITION OF CRANKSHAFT PO-
SITION SENSOR.
Turn the ignition switch to OFF.Is the crankshaft position sen-
sor installation bolt tightened
securely?Go to step 3.Tighten the crank-
shaft position sen-
sor installation bolt
securely.
3 CHECK CRANK SPROCKET.
Remove the front belt cover.Are crank sprocket teeth
cracked or damaged?Replace the crank
sprocket. ME(H4SO)-55,
Crank Sprocket.>Go to step 4.
4 CHECK INSTALLATION CONDITION OF
TIMING BELT.
Turn the crankshaft using ST, and align align-
ment mark on crank sprocket with alignment
mark on cylinder block.
ST 499987500 CRANKSHAFT SOCKETIs the timing belt dislocated
from its proper position?Repair installation
condition of timing
belt. ME(H4SO)-48,
Timing Belt.>Replace the crank-
shaft position sen-
sor. FU(H4SO)-26,
Crankshaft Posi-
tion Sensor.>

EN(H4SO)-159
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 HARNESS BETWEEN CAMSHAFT
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor.
3) Measure the resistance of harness
between camshaft position sensor connector
and engine ground.
Connector & terminal
(E15) No. 1 — Engine ground:Is the resistance more than
100 kΩ?Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
camshaft position
sensor and ECM
connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connectorGo to step 3.
3 CHECK HARNESS BETWEEN CAMSHAFT
POSITION SENSOR AND ECM CONNEC-
TOR.
Measure the resistance of harness between
camshaft position sensor connector and
engine ground.
Connector & terminal
(E15) No. 1 — Engine ground:Is the resistance less than 10
Ω?Repair ground
short circuit in har-
ness between
camshaft position
sensor and ECM
connector.
N
OTE:
The harness be-
tween both con-
nectors are
shielded. Repair
ground short circuit
in harness togeth-
er with shield.Go to step 4.
4 CHECK HARNESS BETWEEN CAMSHAFT
POSITION SENSOR AND ECM CONNEC-
TOR.
Measure the resistance of harness between
camshaft position sensor connector and
engine ground.
Connector & terminal
(E15) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 5.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
camshaft position
sensor and ECM
connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.Is the camshaft position sensor
installation bolt tightened
securely?Go to step 6.Tighten the cam-
shaft position sen-
sor installation bolt
securely.
6 CHECK CAMSHAFT POSITION SENSOR.
1) Remove the camshaft position sensor.
2) Measure the resistance between connector
terminals of camshaft position sensor.
Te r m i n a l
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Go to step 7.Replace the cam-
shaft position sen-
sor. FU(H4SO)-27,
Camshaft Position
Sensor.>

EN(H4SO)-162
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 CURRENT DATA.
1) Start the engine.
2) Read the data of intake manifold absolute
pressure sensor signal using Subaru Select
Monitor or OBD-II scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II Scan Tool Instruction Manual.Is the value more than 53.3
kPa (400 mmHg, 15.75 inHg)?Make sure that the
EGR valve, mani-
fold absolute pres-
sure sensor and
throttle body are
tightened firmly.Go to step 3.
3 CHECK THE POWER SUPPLY OF EGR
VALVE.
1) Disconnect the connector from EGR valve.
2) Turn the ignition switch to ON.
3) Measure the voltage between EGR valve
and engine ground.
Connector & terminal
(E18) No. 2 — Engine ground:
(E18) No. 5 — Engine ground:Is the voltage more than 10 V? Go to step 4.Repair open circuit
in harness
between main
relay and EGR
valve connector.
4 CHECK EGR VALVE.
Measure the resistance between EGR valve
terminals.
N
OTE:
Make sure there is no foreign material between
EGR valve and valve seat.
Te r m i n a l s
No. 1 — No. 2:
No. 3 — No. 2:
No. 4 — No. 5:
No. 6 — No. 5:Is the resistance 20 — 30 Ω? Go to step 5.Replace the EGR
valve. FU(H4SO)-34,
EGR Valve.>
5 OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the connector to ECM and EGR
valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM 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 voltage 0 — 10 V? Repair poor con-
tact portion in
ECM connector.Go to step 6.

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)”. 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. 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. 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)-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)”. 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. to FU(H4SO)-57,
Fuel Level Sen-
sor.> and fuel sub
level sensor. to FU(H4SO)-58,
Fuel Sub Level
Sensor.>