Mitsubishi Montero Sport (2004+). Manual - part 218

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-285

STEP 9. Check for open circuit between left bank heated 
oxygen sensor (front) connector A-09 (terminal No. 2) and 
PCM connector C-90 (terminal No. 57).

NOTE: Check harness after checking intermediate connector 
C-71. If intermediate connector is damaged, repair or replace it. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

Then go to Step 11.
Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 11.
NO :  Repair it. Then go to Step 11.

AK200496

1

2

3

4

A-09(GR)

AB

CONNECTOR: A-09

HARNESS 
CONNECTOR: 
COMPONENT SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK103762

42

43

48

49

50

51

52

53

54

55

56

57

46 45 44

58

59

60

61

62

63

64

65

66

47

41

AB

CONNECTOR: C-90

C-90(GR)

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-286

STEP 10. Check the left bank heated oxygen sensor (front).
(1) Disconnect the left bank heated oxygen sensor (front) 

connector A-09 and connect test harness special tool, 
MB991316, to the connector on the left bank heated oxygen 
sensor (front) side.

(2) Warm up the engine until engine coolant 80

°C (176°F) or 

higher.

(3) Perform a tracing for 5 minutes or more with the engine 

speed of 4,500 r/min.

(4) Connect a digital volt meter between terminal No. 2 (black 

clip) and terminal No. 4 (white clip).

(5) While repeatedly revving the engine, measure the left bank 

heated oxygen sensor (front) output voltage.

Standard value: 0.6 

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wire; 

incorrect connection can damage the oxygen sensor.

• Be careful the heater is broken when voltage of beyond 

8 volts is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate 
400

°

C or more) is not reached although the oxygen sensor 

is normal, the output voltage would be possibly low 
although the rich air-fuel ratio. Therefore, if the output volt-
age is low, use a jumper wire to connect the terminal No.1 
(red clip of special tool) and the terminal No. 3 (blue clip of 
special tool) of the oxygen sensor with a (+) terminal and (-) 
terminal of 8 volts power supply respectively, then check 
again.

Q: Is the voltage between 0.6 and 1.0 volt?

YES : Replace the PCM. Then go to Step 11.
NO :  Replace the left bank heated oxygen sensor (front). 

Then go to Step 11.

AK200496

1

2

3

4

A-09(GR)

AB

CONNECTOR: A-09

HARNESS 
CONNECTOR: 
COMPONENT SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MB991316

WHITE

BLACK

AN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-287

STEP 11. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Procedure 6 − 

Other Monitor 

P.13A-4

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0150 set?

YES : Repeat the troubleshooting.
NO :  The procedure is complete.

DTC P0151: Heated Oxygen Sensor Circuit Low Voltage (bank 2, sensor 1)

AK000490

Left Bank Heated Oxygen Sensor (front) Circuit

WHITE

BL

ACK

RED

BL

ACK

BL

ACK

-RED

C-91

POWERTRAIN CONTROL MODULE (PCM)

FROM MFI RELAY

TO PCM

LEFT BANK HEATED OXYGEN SENSOR (FRONT)

4

71

57

C-90

12

32

2

3

1

22

33

1 2
3 4

A-09
MU802665

71

76

77

72 73 74

75

79 80

78

81

87 88

89

91

90

92

97

98

82

93

83

94

84 85

95

86

96

C-91
(MU803782)

47

41

42 43

48 49 50 51 52 53 54 55 56 57

46

45

44

58

59

60 61 62 63

64 65 66

C-90
(MU803781)

1

10

2 3 4 5 6 7 8 9

11

12 13 14 15 16 17 18 19 20 21 22

23 24 25 26 27 28 29 30 31 32 33

C-71

JOINT
CONNECTOR (4)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-288

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 71) from the output terminal (terminal 
No. 4) of the left bank heated oxygen sensor 
(front).

• Terminal No. 2 of the left bank heated oxygen 

sensor (front) is grounded with PCM (terminal 
No. 57).

.

TECHNICAL DESCRIPTION

• The left bank heated oxygen sensor (front) 

detects the concentration of oxygen in the 
exhaust gas; it converts that data to voltage, and 
sends it to the PCM.

• When the left bank heated oxygen sensor (front) 

begins to deteriorate, the heated oxygen sensor 
signal response deteriorates also.

• The PCM varies the air/fuel mixture to make it 

leaner and richer, and checks the response 
speed of the left bank heated oxygen sensor 
(front). In addition, the PCM also checks for an 
open circuit in the left bank heated oxygen sensor 
(front) output line.

.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (front) output volt-

age stays low when air/fuel ratio is forced to be 
rich. The above procedure is repeated when oxy-
gen sensor is inactive.

.

MONITOR EXECUTION
Continuous

.

AK200495

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

A-09(GR)

AB

CONNECTOR: A-09

AK103912AB

CONNECTOR: C-71

C-71

AK103738AE

CONNECTORS: C-90, C-91

PCM

C-91(GR)

C-90(GR)