Subaru Legacy III (2000-2003 year). Manual - part 146

EN(H4SO)-196

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

AO:DTC P0458 — EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-

TROL VALVE CIRCUIT LOW —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Erroneous idling

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode<Ref. to EN(H4SO)-47, OPER-
ATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)-40, OPERATION, Inspection 
Mode.> .
• WIRING DIAGRAM:

EN-01131

F44

B61

6

RHD

RHD

PURGE CONTROL

SOLENOID VALVE

E4

B22

E3

B47

B47

3

4

1

2

5

6

B134

1 2

3 4

5 6

7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

24 25

26 27 28 29

30 31 32 33

34 35

B22

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

SBF-5

BATTERY

MAIN RELAY

1

2

3

5

4

6

29

2

1

1

2

B134

ECM

F44

1 2 3 4
5 6 7 8

E4

1 2

LHD

LHD

EN(H4SO)-197

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

sis ground.

Connector & terminal

(B134) No. 29 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Even if MI lights 
up, the circuit has 
returned to a nor-
mal condition at 
this time. Contact 
SUBARU distribu-
tor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

Go to step 2.

2

CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from purge control 

solenoid valve and ECM.

3) Measure resistance of harness between 

purge control solenoid valve connector and 
engine ground.

Connector & terminal

(E4) No. 2 — Engine ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 3.

Repair ground 
short circuit in har-
ness between 
ECM and purge 
control solenoid 
valve connector.

3

CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
Measure resistance of harness between ECM 
and purge control solenoid valve of harness 
connector.

Connector & terminal

(B134) No. 29 — (E4) No. 2:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 4.

Repair open circuit 
in harness 
between ECM and 
purge control sole-
noid valve connec-
tor.

NOTE:
In this case, repair
the following:
• Open circuit in 
harness between 
ECM and purge 
control solenoid 
valve connector
• Poor contact in 
coupling connector

4

CHECK PURGE CONTROL SOLENOID 
VALVE.
1) Remove purge control solenoid valve.
2) Measure resistance between purge control 

solenoid valve terminals.

Terminals

No. 1 — No. 2:

Is the measured value within the specified 
range?

10 - 100 

Ω

Go to step 5.

Replace purge 
control solenoid 
valve. <Ref. to 
EC(H4SO)-7, 
Purge Control 
Solenoid Valve.>

EN(H4SO)-198

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

5

CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE.
1) Turn ignition switch to ON.
2) Measure voltage between purge control 

solenoid valve and engine ground.

Connector & terminal

(E4) No. 1 (+) — Engine ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 6.

Repair open circuit 
in harness 
between main 
relay and purge 
control solenoid 
valve connector.

6

CHECK POOR CONTACT.
Check poor contact in purge control solenoid 
valve connector.
Is there poor contact in purge control solenoid 
valve connector?

There is poor contact.

Repair poor con-
tact in purge con-
trol solenoid valve 
connector.

Contact SUBARU 
distributor service.

NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

Step

Value

Yes

No

EN(H4SO)-199

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO: