Mitsubishi Montero (2002-2004). Manual - part 606

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-121

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 109) from the output terminal (terminal 
No. 4) of the right bank heated oxygen sensor 
(front).

• Terminal No. 2 of the right bank heated oxygen 

sensor (front) is grounded with PCM (terminal 
No. 96).

.

TECHNICAL DESCRIPTION

• The right bank heated oxygen sensor (front) 

detects the concentration of oxygen in the 
exhaust gas; it converts those data to voltage, 
and inputs the resulting signals to the PCM.

• When the right bank heated oxygen sensor 

(front) begins to deteriorate, the heated oxygen 
sensor signal response becomes poor.

• The PCM forcibly varies the air/fuel mixture to 

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

.

DTC SET CONDITIONS

Check Conditions

• 3 minutes or more have passed since the starting 

sequence was completed.

• Right bank heated oxygen sensor (front) signal 

voltage has continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C 

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Volume airflow sensor output frequency is 100 Hz 

or more.

• At least 20 seconds have passed since fuel shut 

off control was canceled.

• After the ignition switch is turned "ON" position, 

the changes in the output voltage of the right 
bank heated oxygen sensor (front) is lower than 
0.078 volt.

• Monitoring time: 10 seconds.

Judgement Criteria

• Making the air/fuel ratio 15 percent for 10 sec-

onds richer does not result in raising the heated 
oxygen sensor (front) output voltage beyond 0.2 
volt.

• The PCM monitors for this condition once during 

the drive cycle.

.

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

• Right bank heated oxygen sensor (front) failed.

• Short circuit in right bank heated oxygen sensor 

(front) output line.

• PCM failed.

AK201049

CONNECTOR: D-116

D-116

AC

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-122

DIAGNOSIS

Required Special Tools:

• MB991502: Scan Tool (MUT-II)

• MD998464: Test Harness

STEP 1. Using scan tool MB991502, check data list item 39: 
Heated Oxygen Sensor Bank 1, Sensor 1 (right front).

CAUTION

To prevent damage to scan tool MB991502, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991502 to the data reading mode for item 

39, Heated Oxygen Sensor Bank 1, Sensor 1 (right front).

• Warm up the engine. When the engine is revved, the 

output voltage should measure 0.6 to 1.0 volt.

• Warm up the engine. When the engine is idling, the out-

put voltage should repeat 0.4 volt and 0.6 to 1.0 volt 
alternately.

(4) 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.

AC003081 AB

16 PIN

MB991502

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-123

STEP 2. Check the right bank heated oxygen sensor 
(front).
(1) Disconnect the right bank heated oxygen sensor (front) 

connector B-07 and connect test harness special tool, 
MD998464, to the connector on the right bank heated 
oxygen sensor (front) side.

(2) Warm up the engine until engine coolant 80

°C (176°F) or 

higher.

CAUTION

Be very careful when connecting the jumper wires; incor-
rect connection can damage the right bank heated oxygen 
sensor (front).

(3) Use the jumper wires to connect terminal No. 1 (red clip) to 

the positive battery terminal and terminal No. 3 (blue clip) to 
the negative battery terminal.

(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 right 

bank heated oxygen sensor (front) output voltage.

Standard value: 0.6 

− 1.0 volt

Q: Is the voltage between 0.6 and 1.0 volt?

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

Then go to Step 5.

AK201274

1

2

3

4

CONNECTOR: B-07

B-07(B)

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01625AC

BLUE

RED

BLACK

JUMPER
WIRES

WHITE

MD998464

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-124

STEP 3. Check connector B-07 at right bank heated 
oxygen sensor (front) and connector D-135 at PCM for 
damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 5.

AK201274

1

2

3

4

CONNECTOR: B-07

B-07(B)

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

RIGHT 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)