SUBARU FORESTER 2004 Service Repair Manual

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)-144
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK POWER SUPPLY LINE.
1) Turn the ignition switch to ON.
2) Measure the voltage between fuel injector
and engine ground on faulty cylinders.
Connector & terminal
#1 (E5) No. 2 (+) — Engine ground (
−):
#2 (E16) No. 2 (+) — Engine ground (
−):
#3 (E6) No. 2 (+) — Engine ground (
−):
#4 (E17) No. 2 (+) — Engine ground (
−):Is the voltage more than 10 V? Repair poor con-
tact in all connec-
tors in fuel injector
circuit.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
main relay and fuel
injector connector
on faulty cylinders
 Poor contact in
coupling connector
 Poor contact in
main relay connec-
tor
 Poor contact in
fuel injector con-
nector on faulty
cylinders
7 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) Turn the ignition switch to ON.
4) 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? Repair battery
short circuit in har-
ness between
ECM and fuel
injector. After
repair, replace the
ECM. FU(H4SO)-44,
Engine Control
Module (ECM).>Go to step 8.
8 CHECK FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between fuel injec-
tor terminals on faulty cylinder.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 1
Ω?Replace the faulty
fuel injector to FU(H4SO)-35,
Fuel Injector.> and
ECM. FU(H4SO)-44,
Engine Control
Module (ECM).>Go to step 9.
9 CHECK INSTALLATION OF CAMSHAFT PO-
SITION SENSOR/CRANKSHAFT POSITION
SENSOR.Is the installation of camshaft
position sensor or crankshaft
position sensor loosened?Tighten camshaft
position sensor or
crankshaft posi-
tion sensor.Go to step 10.
10 CHECK CRANK SPROCKET.
Remove the timing belt cover.Is the crank sprocket rusted or
does it have broken teeth?Replace the crank
sprocket. ME(H4SO)-55,
Crank Sprocket.>Go to step 11.
11 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.>Go to step 12.
12 CHECK FUEL LEVEL.Is the fuel meter indication
higher than the “Lower” level?Go to step 13.Replenish fuel so
fuel meter indica-
tion is higher than
the “Lower” level.
After replenishing
fuel, Go to step 13. Step Check Yes No

EN(H4SO)-145
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
13 CHECK STATUS OF MALFUNCTION INDI-
CATOR LIGHT.
1) Clear the memory using Subaru Select
Monitor.

2) Start the engine, and drive the vehicle more
than 10 minutes.Does the malfunction indicator
light illuminate or blink?Go to step 15.Go to step 14.
14 CHECK CAUSE OF MISFIRE DIAGNOSED.Was the cause of misfire diag-
nosed when the engine is run-
ning? Ex. Removed spark plug
cord, etc.Finish diagnostics
operation, if the
engine has no
abnormality.1. Repair the poor
contact.
N
OTE:
In this case repair
the following:
 Poor contact in
ignitor connector
 Poor contact in
ignition coil con-
nector
 Poor contact in
fuel injector con-
nector on faulty
cylinders
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2. If there is no
poor contact,
check the following
items and contact
SUBARU dealer.
 Fuel condi-
tion
 Contained
additive
 Plug condi-
tion
Plug cord
condition
 Engine oil
condition
15 CHECK AIR INTAKE SYSTEM.Is there any fault in air intake
system?Repair air intake
system.
N
OTE:
Check the follow-
ing items:
 Are there air
leaks or air suction
caused by loose or
dislocated nuts
and bolts?
 Are there cracks
or any disconnec-
tion of hoses?Go to step 16. Step Check Yes No

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)-147
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
23 GROUP OF #3 AND #4 CYLINDERS.Are there faults in #3 and #4
cylinders?Repair or replace
the faulty par t.
N
OTE:
 Check the fol-
lowing items:
 Spark plug
 Fuel injector
 Ignition coil
 If no abnormal is
discovered, check
for “16. D: IGNI-
TION CONTROL
SYSTEM” of #3
and #4 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).>
24 GROUP OF #1 AND #3 CYLINDERS.Are there faults in #1 and #3
cylinders?Repair or replace
the faulty par t.
N
OTE:
Check the follow-
ing items:
 Spark plug
 Fuel injector
 Skipping timing
belt teethGo to DTC P0171.
EN(H4SO)-138,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
25 GROUP OF #2 AND #4 CYLINDERS.Are there faults in #2 and #4
cylinders?Repair or replace
the faulty par t.
NOTE:
Check the follow-
ing items:
 Spark plug
 Fuel injector
 Compression
ratio
 Skipping timing
belt teethGo to DTC P0171.
EN(H4SO)-138,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
26 CYLINDER AT RANDOM.Is the engine idle rough? Go to DTC P0171.
EN(H4SO)-138,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>Repair or replace
the faulty part.
N
OTE:
Check the follow-
ing items:
 Spark plug
 Fuel injector
 Compression
ratio Step Check Yes No

EN(H4SO)-148
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AG:DTC P0327 KNOCK SENSOR 1 CIRCUIT LOW INPUT (BANK 1 OR SINGLE
SENSOR)
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Poor driving performance
 Knocking occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-00272
1627
KNOCK
SENSOR
16
2
ECM B135
B22
E3
E14
E14
12
B22
125678
131415169101112
34
17181920
B135
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21

EN(H4SO)-149
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM har-
ness connector and chassis ground.
Connector & terminal
(B135) No. 16 — Chassis ground:Is the resistance more than
700 kΩ?Go to step 2.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
knock sensor and
ECM connector
 Poor contact in
knock sensor con-
nector
 Poor contact in
coupling connector
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.
Te r m i n a l
No. 2 — Engine ground:Is the resistance more than
700 kΩ?Go to step 3.Repair harness
and connector.
NOTE:
In this case repair
the following:
 Poor contact in
knock sensor con-
nector
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.Is the knock sensor installation
bolt tightened securely?Replace the knock
sensor. FU(H4SO)-28,
Knock Sensor.>Tighten knock sen-
sor installation bolt
securely.

EN(H4SO)-150
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AH:DTC P0328 KNOCK SENSOR 1 CIRCUIT HIGH INPUT (BANK 1 OR SINGLE
SENSOR)
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Poor driving performance
 Knocking occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-00272
1627
KNOCK
SENSOR
16
2
ECM B135
B22
E3
E14
E14
12
B22
125678
131415169101112
34
17181920
B135
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21

EN(H4SO)-151
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B135) No. 16 — Chassis ground:Is the resistance less than 400
kΩ?Go to step 2.Go to step 3.
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.
Te r m i n a l s
No. 2 — Engine ground:Is the resistance less than 400
kΩ?Replace the knock
sensor. FU(H4SO)-28,
Knock Sensor.>Repair ground
short circuit in har-
ness between
knock sensor con-
nector and ECM
connector.
N
OTE:
The harness be-
tween both connec-
tors are shielded.
Repair short circuit
in harness covered
with shield.
3 CHECK INPUT SIGNAL FROM ECM.
1) Connect the connectors to ECM and knock
sensor.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B135) No. 16 (+) — Chassis ground (
−):Is the voltage more than 2 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. (How-
ever, the possibility
of poor contact still
remains.)
N
OTE:
In this case repair
the following:
 Poor contact in
knock sensor con-
nector
 Poor contact in
ECM connector.
 Poor contact in
coupling connectorRepair the poor
contact in ECM
connector.

EN(H4SO)-152
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AI: DTC P0335 CRANKSHAFT POSITION SENSOR “A” CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Engine stalls.
 Failure of engine to start
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-00273
12
1917
1728
B22
E3
E10
B22
E10
12
B135ECM CRANKSHAFT
POSITION
SENSOR
125678
131415169101112
34
17181920
6
B135
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21