Content .. 163 164 165 166 ..

Subaru Legacy IV (2008 year). Manual - part 165

EN(H4SO)(diag)-263

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
EN(H4SO)(diag)-
80, List of Diagnos-
tic Trouble Code
(DTC).>

Go to step 2.

CHECK ENGINE OIL.

Is there a proper amount of
engine oil?

Go to step 3.

Replace engine oil.
<Ref. to
LU(H4SO)-10,
REPLACEMENT,
Engine Oil.>

CHECK EXHAUST SYSTEM.

Are there holes or loose bolts
on exhaust system?

Repair the exhaust
system.

Go to step 4.

CHECK AIR INTAKE SYSTEM.

Are there holes, loose bolts or
disconnection of hose on air
intake system?

Repair the air
intake system.

Go to step 5.

CHECK FUEL PRESSURE.

WARNING:
Place “NO OPEN FLAMES” signs near the
working area.

CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(H4SO)-
26, INSPECTION, Fuel Pressure.>

CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.

Is the measured value 339.5 —
360.5 kPa (3.5 — 3.7 kg/cm

49 — 52 psi)?

Go to step 6.

Repair the follow-
ing item.
Fuel pressure is
too high:
• Clogged fuel line
or bent hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel line

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 general scan tool.

NOTE:
• SUBARU SELECT MONITOR
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4SO)(diag)-33, Subaru Select Moni-
tor.>
• General Scan Tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the engine coolant tempera-
ture 75°C (167°F) or higher?

Go to step 7.

Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4SO)-22,
Engine Coolant
Temperature Sen-
sor.>

EN(H4SO)(diag)-264

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For AT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the data of the mass air flow and
intake air temperature sensor signal using Sub-
aru Select Monitor or general scan tool.

Is the measured value 2.0 —
5.0 g/s (0.26 — 0.66 lb/m)?

Go to step 8.

Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4SO)-28,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For AT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the data of the mass air flow and
intake air temperature sensor signal using Sub-
aru Select Monitor or general scan tool.

Subtract ambient temperature
from intake air temperature. Is
the obtained value –10 — 50°C
(–18 — 90°F)?

Go to step 9.

Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to
FU(H4SO)-28,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground on faulty cylinders.

Connector & terminal

#1 (B137) No. 8 (+) — Chassis ground (–):
#2 (B137) No. 9 (+) — Chassis ground (–):
#3 (B137) No. 10 (+) — Chassis ground (–):
#4 (B137) No. 11 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 14.

Go to step 10.

Step

Check

Yes

EN(H4SO)(diag)-265

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between fuel injec-
tor connector and engine ground on faulty cylin-
ders.

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 1 M

: or

more?

Go to step 11.

Repair the short
circuit to ground in
harness between
ECM and fuel
injector connector.

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
Measure the resistance of harness between
ECM and fuel injector on faulty cylinders.

Connector & terminal

#1 (B137) No. 8 — (E5) No. 1:
#2 (B137) No. 9 — (E16) No. 1:
#3 (B137) No. 10 — (E6) No. 1:
#4 (B137) No. 11 — (E17) No. 1:

Is the resistance less than 1

:? Go to step 12.

Repair the harness
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and fuel in-
jector connector
• Poor contact of
coupling connector

CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance between 5 —
20

Go to step 13.

Replace the faulty
fuel injector. <Ref.
to FU(H4SO)-30,
Fuel Injector.>

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 10 V or more?

Repair the poor
contact of all con-
nectors in fuel
injector circuit.

Repair the harness
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
the main relay con-
nector and fuel in-
jector connector on
faulty cylinders
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground on faulty cylinders.

Connector & terminal

#1 (B137) No. 8 (+) — Chassis ground (–):
#2 (B137) No. 9 (+) — Chassis ground (–):
#3 (B137) No. 10 (+) — Chassis ground (–):
#4 (B137) No. 11 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to power in
the harness
between the ECM
and fuel injector.

Go to step 15.

Step

Check

Yes

EN(H4SO)(diag)-266

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CHECK FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between fuel injec-
tor terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance less than 1

:? Replace the faulty

fuel injector. <Ref.
to FU(H4SO)-30,
Fuel Injector.>

Go to step 16.

CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR/CRANK-
SHAFT POSITION SENSOR.

Is the camshaft position sensor
or crankshaft position sensor
loosely installed?

Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.

Go to step 17.

CHECK CRANK SPROCKET.
Remove the timing belt cover. <Ref. to
ME(H4SO)-43, REMOVAL, Timing Belt Cover.>

Is the crank sprocket rusted or
does it have broken teeth?

Replace the crank
sprocket. <Ref. to
ME(H4SO)-50,
Crank Sprocket.>

Go to step 18.

CHECK INSTALLATION CONDITION OF
TIMING BELT.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST

499987500

CRANKSHAFT
SOCKET

Is the timing belt dislocated
from its proper position?

Repair the installa-
tion condition of
timing belt. <Ref. to
ME(H4SO)-44,
Timing Belt.>

Go to step 19.

CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 5 and
No. 6 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.

Terminals

No. 8 — No. 7:

Is the resistance less than 1

:? Go to step 20.

Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(H4SO)-42,
Electronic Throttle
Control Relay.>

CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.

Connector & terminal

(B362) No. 8 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 21.

Repair the open or
ground short circuit
of power supply
circuit.

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Disconnect the connectors from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B362) No. 6 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to power in
the harness
between ECM and
electronic throttle
control relay con-
nector.

Go to step 22.

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B362) No. 6 — Chassis ground:
(B362) No. 7 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 23.

Repair the short
circuit in harness
to ground between
ECM and elec-
tronic throttle con-
trol relay
connector.

Step

Check

Yes

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