Subaru Legacy (2005 year). Manual - part 198

EN(H4SO 2.5)(diag)-77

ENGINE (DIAGNOSTICS)

List of Diagnostic Trouble Code (DTC)

P1572

IMM Circuit Failure (Except Antenna 
Circuit)

<Ref. to IM(diag)-21, DTC P1572 IMM CIRCUIT FAILURE (EXCEPT 
ANTENNA CIRCUIT), Diagnostic Procedure with Diagnostic Trouble Code 
(DTC).>

P1574

Key Communication Failure

<Ref. to IM(diag)-24, DTC P1574 KEY COMMUNICATION FAILURE, Diag-
nostic Procedure with Diagnostic Trouble Code (DTC).>

P1576

EGI Control Module EEPROM

<Ref. to IM(diag)-25, DTC P1576 EGI CONTROL MODULE EEPROM, Diag-
nostic Procedure with Diagnostic Trouble Code (DTC).>

P1577

IMM Control Module EEPROM

<Ref. to IM(diag)-25, DTC P1577 IMM CONTROL MODULE EEPROM, 
Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

P1578

Meter Failure

<Ref. to IM(diag)-25, DTC P1578 METER FAILURE, Diagnostic Procedure 
with Diagnostic Trouble Code (DTC).>

P2100

Throttle Actuator Control Motor Cir-
cuit/Open

<Ref. to EN(H4SO 2.0)(diag)-190, DTC P2100 THROTTLE ACTUATOR 
CONTROL MOTOR CIRCUIT/OPEN, Diagnostic Procedure with Diagnostic 
Trouble Code (DTC).>

P2101

Throttle Actuator Control Motor Cir-
cuit Range/Performance

<Ref. to EN(H4SO 2.0)(diag)-190, DTC P2101 THROTTLE ACTUATOR 
CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Proce-
dure with Diagnostic Trouble Code (DTC).>

P2102

Throttle Actuator Control Motor Cir-
cuit Low

<Ref. to EN(H4SO 2.0)(diag)-197, DTC P2102 THROTTLE ACTUATOR 
CONTROL MOTOR CIRCUIT LOW, Diagnostic Procedure with Diagnostic 
Trouble Code (DTC).>

P2103

Throttle Actuator Control Motor Cir-
cuit High

<Ref. to EN(H4SO 2.0)(diag)-200, DTC P2103 THROTTLE ACTUATOR 
CONTROL MOTOR CIRCUIT HIGH, Diagnostic Procedure with Diagnostic 
Trouble Code (DTC).>

P2109

Throttle/Pedal Position Sensor A 
Minimum Stop Performance

<Ref. to EN(H4SO 2.0)(diag)-202, DTC P2109 THROTTLE/PEDAL POSI-
TION SENSOR “A” MINIMUM STOP PERFORMANCE, Diagnostic Proce-
dure with Diagnostic Trouble Code (DTC).>

P2111

Throttle Actuator Control System - 
Stuck Open

<Ref. to EN(H4SO 2.0)(diag)-202, DTC P2111 THROTTLE ACTUATOR 
CONTROL SYSTEM - STUCK OPEN, Diagnostic Procedure with Diagnostic 
Trouble Code (DTC).>

P2122

Throttle/Pedal Position Sensor/
Switch “D” Circuit Low Input

<Ref. to EN(H4SO 2.0)(diag)-203, DTC P2122 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “D” CIRCUIT LOW INPUT, Diagnostic Procedure 
with Diagnostic Trouble Code (DTC).>

P2123

Throttle/Pedal Position Sensor/
Switch “D” Circuit High Input

<Ref. to EN(H4SO 2.0)(diag)-206, DTC P2123 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “D” CIRCUIT HIGH INPUT, Diagnostic Procedure 
with Diagnostic Trouble Code (DTC).>

P2127

Throttle/Pedal Position Sensor/
Switch “E” Circuit Low Input

<Ref. to EN(H4SO 2.0)(diag)-208, DTC P2127 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “E” CIRCUIT LOW INPUT, Diagnostic Procedure 
with Diagnostic Trouble Code (DTC).>

P2128

Throttle/Pedal Position Sensor/
Switch “E” Circuit High Input

<Ref. to EN(H4SO 2.0)(diag)-211, DTC P2128 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “E” CIRCUIT HIGH INPUT, Diagnostic Procedure 
with Diagnostic Trouble Code (DTC).>

P2135

Throttle/Pedal Position Sensor/
Switch “A”/“B” Voltage Correlation

<Ref. to EN(H4SO 2.0)(diag)-213, DTC P2135 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “A” / “B” VOLTAGE CORRELATION, Diagnostic 
Procedure with Diagnostic Trouble Code (DTC).>

P2138

Throttle/Pedal Position Sensor/
Switch “D”/“E” Voltage Correlation

<Ref. to EN(H4SO 2.0)(diag)-218, DTC P2138 THROTTLE/PEDAL POSI-
TION SENSOR/SWITCH “D” / “E” VOLTAGE CORRELATION, Diagnostic 
Procedure with Diagnostic Trouble Code (DTC).>

P2503

Charging System Voltage Low

<Ref. to EN(H4SO 2.0)(diag)-221, DTC P2503 CHARGING SYSTEM VOLT-
AGE LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

P2504

Charging System Voltage High

<Ref. to EN(H4SO 2.0)(diag)-222, DTC P2504 CHARGING SYSTEM VOLT-
AGE HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

DTC

Item

Reference

EN(H4SO 2.5)(diag)-78

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

18.Diagnostic Procedure with Diagnostic Trouble Code (DTC)

A: DTC P0030 HO2S HEATER CONTROL CIRCUIT (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
Detects when malfunction occurs in 2 continuous driving cycles.

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03457

3

4

1

2

5

6

B327

SBF-5

E

E

B327

E24

6
4

5
3

2
1

25

33

26

3

2

6

7

52

B134

B21

E2

B21

E2

50

51

3

4

E2

B21

E

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

E24

B134

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

33 34

29

32

30 31

ECM

BATTERY

FRONT OXYGEN

(A/F) SENSOR

OXYGEN (A/F) 
SENSOR RELAY

1

3

4 5 6

2

3

4

1

6

EN(H4SO 2.5)(diag)-79

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

CHECK OPTION CODE.

Is the option code EC, EK, EH, 
ER or K4?

Go to step 2.

Refer to EN(H4SO 
2.0) section. <Ref. 
to EN(H4SO 
2.0)(diag)-64, List 
of Diagnostic Trou-
ble Code (DTC).>

NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.

2

CHECK HARNESS BETWEEN ECM AND 
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connectors from ECM and 
front oxygen (A/F) sensor.
4) Measure the resistance of harness 
between ECM and front oxygen (A/F) sensor 
connector.

Connector & terminal

(B134) No. 2 — (E24) No. 6:
(B134) No. 3 — (E24) No. 6:

Is the resistance less than 1 
Ω?

Go to step 3.

Repair the open 
circuit of harness 
between ECM and 
front oxygen (A/F) 
sensor connector.

3

CHECK HARNESS BETWEEN ECM AND 
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between 
ECM and front oxygen (A/F) sensor connector.

Connector & terminal

(B134) No. 26 — (E24) No. 1:
(B134) No. 33 — (E24) No. 3:

Is the resistance less than 1 
Ω?

Go to step 4.

Repair the open 
circuit of harness 
between ECM and 
front oxygen (A/F) 
sensor connector.

4

CHECK HARNESS BETWEEN OXYGEN (A/
F) SENSOR RELAY AND FRONT OXYGEN 
(A/F) SENSOR CONNECTOR.
Measure the resistance of harness between 
oxygen (A/F) sensor relay and front oxygen (A/
F) sensor connector.

Connector & terminal

(B327) No. 4 — (E24) No. 4:

Is the resistance less than 1 
Ω?

Go to step 5.

Repair the open 
circuit of harness 
between oxygen 
(A/F) sensor relay 
and front oxygen 
(A/F) sensor con-
nector.

5

CHECK FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen 
(A/F) sensor connector terminals.

Terminals

No. 4 — No. 6:

Is the resistance less than 5 
Ω?

Go to step 6.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4SO 2.5)-35, 
Front Oxygen (A/
F) Sensor.>

6

CHECK POOR CONTACT.
Check poor contact in ECM and front oxygen 
(A/F) sensor connector.

Is there poor contact in ECM or 
front oxygen (A/F) sensor con-
nector?

Repair the poor 
contact in ECM or 
front oxygen (A/F) 
sensor.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4SO 2.5)-35, 
Front Oxygen (A/
F) Sensor.>

EN(H4SO 2.5)(diag)-80

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

B: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:
Immediately at fault recognition

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO 2.5)(diag)-
40, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO 2.5)(diag)-33, Inspection Mode.>.
WIRING DIAGRAM:
• EC, EK, EH, ER and K4 model

• KA and KS model

NOTE:
Fuel injection system for KA and KS model is the same as 2.0 L model. Refer to EN(H4SO 2.0) section.

EN-03457

3

4

1

2

5

6

B327

SBF-5

E

E

B327

E24

6
4

5
3

2
1

25

33

26

3

2

6

7

52

B134

B21

E2

B21

E2

50

51

3

4

E2

B21

E

B21

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

E24

B134

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

33 34

29

32

30 31

ECM

BATTERY

FRONT OXYGEN

(A/F) SENSOR

OXYGEN (A/F) 
SENSOR RELAY

1

3

4 5 6

2

3

4

1

6