Subaru Legacy III (2000-2003 year). Manual - part 131

EN(H4SO)-136

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Q: DTC P0125 — INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED 

LOOP FUEL CONTROL —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM:

• Engine would not return to 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-01125

19

12

9

13

B135 ECM

2

1

E2

B21

E8

ENGINE

COOLANT

TEMPERATURE 

SENSOR

E8

B21

1 2

3 4

5

6 7

8

9 10

11 12

13

14 15

16

17 18

19 20

1 2

3

5 6 7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26

27 28

16 17 18 19

20 21

B135

B83

1 2 3 4 5 6

B83

3

1

FG

2

4

EG

: FOR G.C.C COUNTRIES MODEL 

: EXCEPT FOR G.C.C COUNTRIES MODEL 

FG

EG

EN(H4SO)-137

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?

DTC indicated.

Inspect the rele-
vant DTC using 
“List of Diagnostic 
Trouble Code 
(DTC)”. <Ref. to 
EN(H4SO)-83, List 
of Diagnostic 
Trouble Code 
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0125.

Go to step 2.

2

CHECK THERMOSTAT.
Does thermostat remain opened?

Thermostat remains opened.

Replace thermo-
stat. <Ref. to 
CO(H4SO)-21, 
Thermostat.>

Replace engine 
coolant tempera-
ture sensor. <Ref. 
to FU(H4SO)-26, 
Engine Coolant 
Temperature Sen-
sor.>

EN(H4SO)-138

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

R: DTC P0129 — BAROMETRIC PRESSURE TOO LOW —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

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.> .

Step

Value

Yes

No

1

CHECK ANY OTHER DTC ON DISPLAY.
Does the Subaru Select Monitor or OBD-II 
general scan tool indicate DTC P0129?

DTC P0129 indicated.

Replace ECM.  
<Ref. to 
FU(H4SO)-45, 
Engine Control 
Module.>

NOTE:
Atmospheric pres-
sure sensor is built
into ECM.

It is not necessary 
to inspect DTC 
P0129.

EN(H4SO)-139

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO: