Mitsubishi Montero (2004+). Manual - part 217

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-355

STEP 3. Check harness connector C-15 at left bank heated 
oxygen sensor (rear) and harness connector D-135 at PCM 
for damage.

Q: Is the harness connector in good condition?

YES : Replace the PCM. Then go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 4.

STEP 4. 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 4 − 

Heated Oxygen Sensor Monitor 

P.13A-4

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0159 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

AK201280

1

2

3

4

CONNECTOR: C-15

C-15(B)

AC

HARNESS 
CONNECTOR: 
COMPONENT SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

AK200947

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

CONNECTOR: D-135

HARNESS CONNECTOR: 
COMPONENT SIDE

AB

PCM

D-135(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-356

DTC P0161: Heated Oxygen Sensor Heater Circuit (bank 2, sensor 2)

TO PCM

TO PCM

WHITE-

BL

ACK

WHITE-

BL

ACK

AK201138

RED

BL

ACK

-BL

U

E

RED

BL

ACK

-BL

U

E

LEFT BANK HEATED
OXYGEN SENSOR (REAR)

4

1 2
3

B-22X

3

2

4

1

BATTERY

4

14

1

3

2

4

18

MFI
RELAY

POWERTRAIN
CONTROL
MODULE (PCM)

4

3

1 2

C-15

MU802605

9

6

10

17

18

29

2

3 4

7 8

19 20

30 31

12

11

24

33 34 35

21

32

27

26

36 37

28

38

25

13

15

14

16

23

22

1

5

E-114

Left Bank Heated Oxygen Sensor (rear) Heater Circuit

1

2

3

5

6 7 8 9

4

20

21 22

232425

2627

10111213

14 15

16 1718

19

D-132

(MU803802)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-357

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

No. 1) to the left bank heated oxygen sensor 
(rear) heater.

• The PCM (terminal No. 18) controls continuity to 

the left bank heated oxygen sensor (rear) heater 
by turning the power transistor in the PCM "ON" 
and "OFF".

.

TECHNICAL DESCRIPTION

• The PCM checks whether the heater current is 

within a specified range when the heater is ener-
gized.

.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor heater (rear) current 

is out of specified range when engine coolant 
temperature is over 20

°C (68°F).

.

MONITOR EXECUTION
Continuous

.

MONITOR EXECUTION CONDITIONS (Other 
monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be 

normal)

• Engine coolant temperature sensor

.

AK201039

MFI RELAY

B-22X

AB

CONNECTOR: B-22X

AK201279

CONNECTOR: C-15

C-15(B)

AD

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

AK201038

CONNECTOR: D-132

AB

PCM

D-132(GR)

AK201052

CONNECTOR: E-114

E-114

AC

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-358

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• 60 seconds have elapsed from the start of the 

previous monitoring.

• Engine coolant temperature is higher than 20°C 

(68

°F).

• While the left bank heated oxygen sensor (rear) 

heater is on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgment Criteria

• The left bank heated oxygen sensor (rear) heater 

current has continued to be lower than 0.16 
ampere or higher than 5.0 ampere for 4 seconds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13A-4

.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are: )

• Left bank heated oxygen sensor (rear) deterio-

rated.

• Open or shorted left bank heated oxygen sensor 

(rear) heater circuit or harness damage.

• Connector damage.

• PCM failed.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 5.0A

AK302937