Mitsubishi Montero (2004+). Manual - part 212

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-335

STEP 12. Check for harness damage between left bank 
heated oxygen sensor (rear) connector C-15 (terminal No. 
2) and PCM connector D-135 (terminal No. 96).

NOTE: Check harness after checking intermediate connector 
E-112. If intermediate connector E-112 is damaged, repair or 
replace it. Refer to GROUP 00E, Harness Connector Inspec-
tion 

P.00E-2

. Then go to Step 15.

Q: Is the harness wire in good condition?

YES : Go to Step 13.
NO :  Repair it. Then go to Step 15.

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-336

STEP 13. Check for short circuit to ground and harness 
damage between left bank heated oxygen sensor (rear) 
connector C-15 (terminal No. 4) and PCM connector D-135 
(terminal No. 116).

NOTE: Check harness after checking intermediate connector 
E-112. If intermediate connector E-112 is damaged, repair or 
replace it. Refer to GROUP 00E, Harness Connector Inspec-
tion 

P.00E-2

. Then go to Step 15.

Q: Is the harness wire in good condition?

YES : Go to Step 14.
NO :  Repair it. Then go to Step 15.

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-337

STEP 14. Check the left bank heated oxygen sensor (rear).

(1) Disconnect the left bank heated oxygen sensor (rear) 

connector C-15 and connect test harness special tool 
MD998464 to the connector on the left bank heated oxygen 
sensor (rear) side.

(2) Warm up the engine until engine coolant temperature 

reaches 80

°C (176°F) or higher.

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

speed of 4,500 r/min.

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

(black clip of special tool) and terminal No. 4 (white clip of 
special tool).

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

heated oxygen sensor (rear) output voltage.

Standard value: 0.6 

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wire; 

incorrect connection can damage the left bank heated 
oxygen sensor (rear).

• Be careful the heater is broken when voltage of beyond 

8 volts is applied to the left bank heated oxygen sensor 
(rear) heater.
NOTE: If the sufficiently high temperature [of approximate 
400

°

C (752

°

F) or more] is not reached although the left 

bank heated oxygen sensor (rear) is normal, the output volt-
age would be possibly low although the rich air/fuel ratio. 
Therefore, if the output voltage 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 left bank 
heated oxygen sensor (rear) with the positive terminal and 
the negative 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 15.
NO :  Replace the left bank heated oxygen sensor (rear). 

Then go to Step 15.

STEP 15. 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 P0156 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)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MD998464

WHITE

BLACK

AL

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-338

DTC P0157: Heated Oxygen Sensor Circuit Low Voltag (bank 2, sensor 2)

WHITE

BL

ACK

BL

ACK

WHITE

BL

ACK

BL

ACK

BL

ACK

AK201137

TO PCM

FROM MFI RELAY

96

116

2

4

3

1

2

1

4 5 6

3

E-112

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

POWERTRAIN CONTROL
MODULE (PCM)

10

9

1

3

7

4

3

1 2

C-15

MU802605

1

12

23 24 25 26

2

13

3

14

4

15

5

16

6

17

7

18

8

19

9

20 21 22

27 28 29 30 31 32 33

10 11

D-116

1
5

7 8

3 4
9 10

2
6

D-14

MU801335

Left Bank Heated Oxygen Sensor (rear) Circuit

9192

939495

96979899

100

105

113114

115116117

118119120

106

107108109

110111112

101102103

104

D-135

(MU803805)