Mitsubishi Lancer Evolution IX. Manual — part 403

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-87

STEP 9. Check harness between B-113 (terminal
No. 1) oxygen sensor (front) connector and
B-12X (terminal No. 4) engine control relay
connector.

• Check power supply line for damage.

Q: Is the check result normal?

YES :

Go to Step 10 .

NO :

Repair the damaged harness wire.

STEP 10. Check harness between B-113 (terminal
No. 3) oxygen sensor (front) connector and C-121
(terminal No. 3) engine-ECU connector.

• Check earthing line for damage.

AK305011

1

2

3

4

AB

Connector : B-113

Harness side
connector

B-113(B)

Oxygen sensor(front)

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side
connector

Relay box’s
triangle marks

AK305011

1

2

3

4

AB

Connector : B-113

Harness side
connector

B-113(B)

Oxygen sensor(front)

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-88

Q: Is the check result normal?

YES :

Go to Step 11 .

NO :

Repair the damaged harness wire.

STEP 11. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES :

Replace the engine-ECU.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

Code No. P0136: Oxygen Sensor (rear) System

OPERATION

• The sensor signal is inputted to the engine-ECU

(terminal No. 73) from the oxygen sensor (rear)
output terminal (terminal No. 1).

• The oxygen sensor (rear) (terminal No. 2) is

earthed with engine-ECU (terminal No. 49).

FUNCTION

• The oxygen sensor (rear) converts the concentra-

tion of oxygen in the exhaust emission into a volt-
age signal and inputs the voltage signal to the
engine-ECU.

AK501807

3 4

2

1

65

43
50

42
49

41
48
60 61

64

46 47
58 59
67 68

45

56
66

52

51

44

53

62

54

63

57

55

80

87

81

94

85

82

84

93

86

98

99

74

92

73

83

88

91

95

97

96

100

89

78

71

90

76 77

75

72
79

Engine-ECU

Oxygen sensor (rear)

From engine control relay

To engine-ECU

49

73

Oxygen sensor (rear) circuit

Wire colour code
B: Black LG: Light green G: Green L: Blue W: White Y: Yellow SB: Sky blue BR: Brown O: Orange GR: Gray
R: Red P: Pink V: Violet PU: Purple

3

2

4

1

B

W

C-119

(MU803782)

C-137

MU801446

AB

C-117

(MU803783)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-89

• When the air-fuel ratio is richer than the theoreti-

cal air-fuel ratio, the oxygen sensor (rear) outputs
a voltage of about 1 V. When it is leaner than the
theoretical air-fuel ratio, it outputs a voltage of
about 0 V.

• In response to the signal, the engine-ECU con-

trols the fuel infection amount so that the air-fuel
ratio can be equivalent to the theoretical air-fuel
ratio.

TROUBLE JUDGMENT

Check Conditions

• Above 3 minutes later after the engine has

started up.

• The engine coolant temperature is 80°C or

higher.

• The volumetric efficiency is 25% or more.

• The engine speed is 1,200 r/min. or more.

Judgment Criterion

• When the oxygen sensor (rear) output voltage is

0.2 V or less, and a power voltage of 5 V is
applied to the oxygen sensor (rear) in the
engine-ECU, the sensor output voltage is 4.5 V or
more.

PROBABLE CAUSES

• Failed oxygen sensor (rear)

• Open/short circuit in oxygen sensor (rear) circuit

or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III data list

• Refer to Data List Reference Table

P.13A-372

.

a. Item No. 59: Oxygen sensor (rear)

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Go to Step 2 .

STEP 2. Connector check: C-137 oxygen sensor
(rear) connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace the connector.

STEP 3. Perform resistance measurement at
C-137 oxygen sensor (rear) connector.

• Disconnect connector, and measure at harness

side.

• Resistance between terminal No. 2 and earth.

OK: 2

Ω or less

Q: Is the check result normal?

YES :

Go to Step 7 .

NO :

Go to Step 4 .

AK305013

2 1

3

4

AB

Oxygen sensor(rear)

Connector : C-137

Harness side
connector

C-137

AK305013

2 1

3

4

AB

Oxygen sensor(rear)

Connector : C-137

Harness side
connector

C-137

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-90

STEP 4. Connector check: C-119 engine-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 5 .

NO :

Repair or replace the connector.

STEP 5. Check harness between C-137 (terminal
No. 2) oxygen sensor (rear) connector and C-119
(terminal No. 49) engine-ECU connector.

• Check earthing line for open circuit and damage.

Q: Is the check result normal?

YES :

Go to Step 6 .

NO :

Repair the damaged harness wire.

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305013

2 1

3

4

AB

Oxygen sensor(rear)

Connector : C-137

Harness side
connector

C-137

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>