Subaru Legacy III (2000-2003 year). Service manual — part 350

EN(H6DO)-202

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AO:DTC P0306 — CYLINDER 6 MISFIRE DETECTED —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault
• Immediately at fault recognition (A misfire which could damage catalyst occurs.)

• TROUBLE SYMPTOM:

• Engine stalls.
• Erroneous idling
• Rough driving

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.
• WIRING DIAGRAM:

EN-01086

B22

F46

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

E6

E17

E5

E16

E43

E44

1

2

1

2

1

2

1

2

C5

C6

D1

C4

16

10

15

14

13

ECM

B137

D:

B136

C:

E5

E16

E6

E17

B22

E3

FUEL INJECTOR

No. 1

FUEL INJECTOR

No. 2

FUEL INJECTOR

No. 3

FUEL INJECTOR

No. 4

BATTERY

D2

D3

D: B137

1

2

1

2

C3

C1

12

9

E43

E44

FUEL INJECTOR

No. 5

FUEL INJECTOR

No. 6

SBF-5

F46

B108

2

B47

MAIN RELAY

1

2

3

5

4

6

B47

3

4

1

2

5

6

B136

C:

3 4

1 2

1 2

7

8 9

5

6

3

4

10 11 12
19 20 21

13 14 15 16

17 18

22 23 24

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

RHD

LHD

RHD

LHD

1 2

EN(H6DO)-203

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0301, P0302,
P0303, P0304,
P0305 and P0306.

Go to step 2.

2

CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector

and chassis ground on faulty cylinders.

Connector & terminal

#1 (B137) No. 1 (+) — Chassis ground
(

−−−−

):

#2 (B136) No. 6 (+) — Chassis ground
(

−−−−

):

#3 (B136) No. 5 (+) — Chassis ground
(

−−−−

):

#4 (B136) No. 4 (+) — Chassis ground
(

−−−−

):

#5 (B136) No. 3 (+) — Chassis ground
(

−−−−

):

#6 (B136) No. 1 (+) — Chassis ground
(

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 7.

Go to step 3.

3

CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from fuel injector on

faulty cylinders.

3) Measure resistance between ECM connec-

tor 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:
#5 (E43) No. 1 — Engine ground:
#6 (E44) No. 1 — Engine ground:

Is the measured value less than the speci-
fied value?

10

Ω

Repair ground
short circuit in har-
ness between fuel
injector and ECM
connector.

Go to step 4.

EN(H6DO)-204

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

4

CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
Measure resistance of harness connector
between ECM connector and fuel injector on
faulty cylinders.

Connector & terminal

#1 (B137) No. 1 — (E5) No. 1:
#2 (B136) No. 6 — (E16) No. 1:
#3 (B136) No. 5 — (E6) No. 1:
#4 (B136) No. 4 — (E17) No. 1:
#5 (B136) No. 3 — (E43) No. 1:
#6 (B136) No. 1 — (E44) No. 1:

Is the measured value less than the specified
value?

1

Ω

Go to step 5.

Repair harness
and connector.

NOTE:
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 resistance between fuel injector ter-
minals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the measured value within the specified
range?

5 — 20

Ω

Go to step 6.

Replace faulty fuel
injector. <Ref. to
FU(H6DO)-39,
Fuel Injector.>

6

CHECK POWER SUPPLY LINE.
1) Turn ignition switch to ON.
2) Measure 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 (

−−−−

):

#5 (E43) No. 2 (+) — Engine ground (

−−−−

):

#6 (E44) No. 2 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Repair poor con-
tact in all connec-
tors in fuel injector
circuit.

Repair harness
and connector.

NOTE:
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 con-
nector
• Poor contact in
fuel injector con-
nector on faulty
cylinders

Step

Value

Yes

No

EN(H6DO)-205

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

7

CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from fuel injector on

faulty cylinder.

3) Turn ignition switch to ON.
4) Measure voltage between ECM connector

and chassis ground on faulty cylinders.

Connector & terminal

#1 (B137) No. 1 (+) — Chassis ground
(

−−−−

):

#2 (B136) No. 6 (+) — Chassis ground
(

−−−−

):

#3 (B136) No. 5 (+) — Chassis ground
(

−−−−

):

#4 (B136) No. 4 (+) — Chassis ground
(

−−−−

):

#5 (B136) No. 3 (+) — Chassis ground
(

−−−−

):

#6 (B136) No. 1 (+) — Chassis ground
(

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Repair battery
short circuit in har-
ness between
ECM and fuel
injector. After
repair, replace
ECM. <Ref. to
FU(H6DO)-46,
Engine Control
Module.>

Go to step 8.

8

CHECK FUEL INJECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between fuel injector

terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the measured value less than the speci-
fied value?

1

Ω

Replace faulty fuel
injector <Ref. to
FU(H6DO)-39,
Fuel Injector.> and
ECM <Ref. to
FU(H6DO)-46,
Engine Control
Module.>.

Go to step 9.

9

CHECK INSTALLATION OF CAMSHAFT PO-
SITION SENSOR/CRANKSHAFT POSITION
SENSOR.
Is camshaft position sensor or crankshaft posi-
tion sensor loosely installed?

Loosely installed.

Tighten camshaft
position sensor or
crankshaft posi-
tion sensor.

Go to step 10.

10

CHECK CRANKSHAFT PLATE.
Is crankshaft plate rusted or does it have bro-
ken teeth?

Rusted or teeth is broken.

Replace crank-
shaft plate.

Go to step 11.

11

CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn crankshaft using ST, and align alignment
mark on crankshaft sprocket with alignment
mark.
ST

18252AA000 CRANKSHAFT SOCKET

Is timing chain dislocated from its proper posi-
tion?

Dislocated from proper posi-
tion.

Repair installation
condition of timing
chain. <Ref. to
ME(H6DO)-41,
Timing Chain
Assembly.>

Go to step 12.

12

CHECK FUEL LEVEL.
Is the fuel meter indication lower than the
“Lower” level?

The indication is lower.

Replenish fuel so
fuel meter indica-
tion is higher than
the “Lower” level.
After replenishing
fuel, Go to step 13.

Go to step 13.

Step

Value

Yes

No