Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 293

EN(H4DOTC)(diag)-396

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

2

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

Connector & terminal

Models without SI-DRIVE

(B136) No. 19 — (E22) No. 1:
(B136) No. 18 — (E22) No. 3:

Models with SI-DRIVE

(B136) No. 19 — (B379) No. 4:
(B136) No. 18 — (B379) No. 3:

Is the resistance less than 1 Ω? Go to step

3.

Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.

3

CHECK FOR POOR CONTACT.
Check for poor contact of the front oxygen (A/F)
sensor connector.

Is there poor contact of front
oxygen (A/F) sensor connec-
tor?

Repair the poor
contact of front
oxygen (A/F) sen-
sor connector.

Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(STI)-54, Front
Oxygen (A/F) Sen-
sor.> <Ref. to
FU(w/o STI)-53,
Front Oxygen (A/F)
Sensor.>

Step

Check

Yes

No

EN(H4DOTC)(diag)-397

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

EY:DTC P2196 O2 SENSOR SIGNAL BIASED/STUCK RICH (BANK 1 SENSOR 1)

DTC DETECTING CONDITION:

• Detected when 2 consecutive driving cycles with fault occur.

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-269, DTC P2196 O2 SENSOR SIGNAL BIASED/

STUCK RICH (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

WIRING DIAGRAM:

• Models without SI-DRIVE <Ref. to WI-32, WITHOUT SI-DRIVE, WIRING DIAGRAM, Engine Electrical

System.>

ECM

B138

6

4 5

3

2

1

E22

1

2

3

15

43

26

B21

E2

44

2

E2

B21

1 2
3 4

E22

B220

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32 35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

2

1

B220

15A

9

10

11
12

B220

D:

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B137

C: B136

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

*

*

*

B138

D1

36

A4

40

34

35

B21

E2

D3

A6

A3

A:

54

52 53

50 51

48 49

46 47

45

44

42 43

40 41

38 39

36 37

34 35

33

32

31

30

29

28

27

26

25

24

23

22

21

20

11

10

9

19

18

17

16

8

7

6

5

15

14

13

12

4

3

2

1

D: B137

C: B136

A:

31

30

32

29

34

33

21

20

19

18

17

16

28

27

26

15

14

13

12

11

25

23

22

24

10

3

4

9

1

2

8

7

6

5

B134

B21

B134

C9

C19

C1

8

C6

C5

EN-08720

E

E

E

SBF-5

BATTERY

: TERMINAL No. OPTIONAL ARRANGEMENT

A/F, OXYGEN SENSOR

RELAY

FUSE

(RELAY BLOCK)

FRONT OXYGEN (A/F)

SENSOR

EN(H4DOTC)(diag)-398

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

• Models with SI-DRIVE <Ref. to WI-48, WITH SI-DRIVE, WIRING DIAGRAM, Engine Electrical System.>

Step

Check

Yes

No

1

CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.

Has water entered the connec-
tor?

Completely
remove any water
inside.

Go to step

2.

2

CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and chassis ground.

Connector & terminal

(B136) No. 19 — Chassis ground:
(B136) No. 18 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

3.

Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.

ECM

B138

6

4 5

3

2

1

1

2

3

4

B220

13
14

15 16

17

27

24

25
26

20

21
22

23

29
30

31

28

32 35

33
34

37
38

39

36

40

8

9

10

11 12

1

2

5

3

4

7

6

19

18

2

1

B220

15A

9

10

11
12

B220

D:

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B137

C: B136

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

*

*

*

B138

D1

36

D3

A4

40

34

35

B21

E2

A6

A3

A:

54

52 53

50 51

48 49

46 47

45

44

42 43

40 41

38 39

36 37

34 35

33

32

31

30

29

28

27

26

25

24

23

22

21

20

11

10

9

19

18

17

16

8

7

6

5

15

14

13

12

4

3

2

1

D: B137

C: B136

A:

31

30

32

29

34

33

21

20

19

18

17

16

28

27

26

15

14

13

12

11

25

23

22

24

10

3

4

9

1

2

8

7

6

5

B134

B379

B21

B379

4

2

3

1

B134

C9

C19

C1

8

C6

C5

EN-08721

SBF-5

E

E

FRONT OXYGEN (A/F)

SENSOR

BATTERY

: TERMINAL No. OPTIONAL ARRANGEMENT

A/F, OXYGEN SENSOR

RELAY

FUSE

(RELAY BLOCK)

EN(H4DOTC)(diag)-399

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

3

CHECK OUTPUT SIGNAL FOR ECM.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and chassis ground.

Connector & terminal

(B136) No. 19 (+) — Chassis ground (–):

Is the voltage 4.5 V or more?

Go to step

5.

Go to step

4.

4

CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.

Connector & terminal

(B136) No. 18 (+) — Chassis ground (–):

Is the voltage 4.95 V or more? Go to step

5.

Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(STI)-54, Front
Oxygen (A/F) Sen-
sor.> <Ref. to
FU(w/o STI)-53,
Front Oxygen (A/F)
Sensor.>

5

CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.

Connector & terminal

(B136) No. 19 (+) — Chassis ground (–):
(B136) No. 18 (+) — Chassis ground (–):

Is the voltage 8 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
After repair,
replace the ECM.
<Ref. to FU(STI)-
59, Engine Control
Module (ECM).>
<Ref. to FU(w/o
STI)-57, Engine
Control Module
(ECM).>

Repair the poor
contact of ECM
connector.

Step

Check

Yes

No