Mitsubishi Montero (2004+). Manual - part 203

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-299

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MD991316: Test Harness

STEP 1. Using scan tool MB991958, check data list item 11: 
Heated Oxygen Sensor Bank 2, Sensor 1 (left front).

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.

(3) Set scan tool MB991958 to the data reading mode for item 

11, Heated Oxygen Sensor Bank 2, Sensor 1 (left front).

(4) Warm up the engine, 2,500 r/min.

• Output voltage repeats 0.4 volt or less and 0.6 − 1.0 volt 

10 times or more within 10 seconds.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-6

.

NO :  Go to Step 2. 

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-300

STEP 2. Check the left bank heated oxygen sensor (front).

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

connector B-26 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 temperature 

reaches 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 (front) 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 (front).

• Be careful the heater is broken when voltage of beyond 

8 volts is applied to the left bank heated oxygen sensor 
(front) 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 (front) is normal, the output 
voltage 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 (front) with the positive terminal 
and the negative terminal of 8 volts power supply respec-
tively, then check again.

Q: Is the voltage between 0.6 and 1.0 volt?

YES : Go to Step 3.
NO :  Replace the left bank heated oxygen sensor (front). 

Then go to Step 4.

AK201278

1

2

3

4

CONNECTOR: B-26

B-26(GR)

AC

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-301

STEP 3. Check harness connector B-26 at left bank heated 
oxygen sensor (front) 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 P0153 set?

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

AK201278

1

2

3

4

CONNECTOR: B-26

B-26(GR)

AC

HARNESS 
CONNECTOR: 
COMPONENT 
SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

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-302

DTC P0154: Heated Oxygen Sensor Circuit No Activity Detected (bank 2, sensor 1)

.

Heated Oxygen Sensor Circuit No Activity 
Detected (bank 2, sensor 1) Circuit

• Refer to DTC P0150 − Left Bank Heated Oxygen 

Sensor (Front) Circuit 

P.13A-268

.

• Refer to, DTC P0201, P0202, P0203, P0204, 

P0205, P0206 

− Injector Circuit 

P.13A-421

.

.

CIRCUIT OPERATION

• Refer to DTC P0152 − Left Bank Heated Oxygen 

Sensor (Front) Circuit 

P.13A-291

.

• Refer to, DTC P0201, P0202, P0203, P0204, 

P0205, P0206 

− Injector Circuit 

P.13A-421

.

.

TECHNICAL DESCRIPTION

• The PCM effects air/fuel ratio feedback control in 

accordance with the signals from the left bank 
heated oxygen sensor (front).

• If the left bank heated oxygen sensor (front) has 

deteriorated, corrections will be made by the 
heated oxygen sensor (rear).

• DTC P0154 becomes stored in memory if a fail-

ure is detected in the above air/fuel ratio feed-
back control system.

.

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

age does not cross 0.5 volt within specified 
period.

.

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)

• Misfire monitor

Sensor (The sensor below is determined to be 

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.