Mitsubishi Montero (2002-2004). Manual - part 629

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-213

STEP 2. Check for short circuit to power supply between
left bank heated oxygen sensor (front) connector B-26
(terminal No. 4) and PCM connector D-135 (terminal No.
108).
Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 3.
NO : Repair it. Then go to Step 3.

STEP 3. Perform the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Trouble Code Diagnosis

− OBD-II Drive Cycle

− Procedure 6 − Other Monitor

P.13Ab-2

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0152 set?

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

AK201278

CONNECTOR: B-26

B-26(GR)

HARNESS
CONNECTOR:
COMPONENT
SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK200947

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

PCM

D-135(GR)

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-214

DTC P0153: Heated Oxygen Sensor Circuit Slow Response (bank 2, sensor 1)

ACK

TO PCM

FROM MFI RELAY

WHITE

AK201135

108

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

1 2

B-26

MU802665

23 24 25 26

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 (front) Circuit

9192

939495

96979899

100

105

113114

115116117

118119120

106

107108109

110111112

101102103

104

D-135

(MU803805)

AK201277

CONNECTOR: B-26

B-26(GR)

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK201038AF

CONNECTOR: D-135

PCM

D-135(GR)

AK201049

D-14

CONNECTOR: D-14

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-215

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 108) 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. 96).

TECHNICAL DESCRIPTION

• The left 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 left bank heated oxygen sensor (front)

begins to deteriorate, the left bank 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 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.

DTC SET CONDITIONS

Check Conditions

• Engine coolant temperature is higher than 50°C

(122

°F).

• Engine speed is at between 1,250 and 3,000 r/

min.

• Volumetric efficiency is at between 24 and 65

percent.

• Under the closed loop air/fuel control.

• The throttle valve is open.

• Short-term fuel trim is at between −30 and +25

percent.

• More than 3 seconds have elapsed after the

abovementioned conditions have been met.

• The PCM monitors for this condition for 7 cycles

of 12 seconds each during the drive cycle.

Judgment Criteria

• The left bank heated oxygen sensor (front) sends

"lean" and "rich" signals alternately 11 times or
less for 12 seconds.

NOTE: If the sensor switching frequency is lower
than the Judgment Criteria due to the MUT-II OBD-II
test Mode

−

H02S Test Results, it is assumed that

the heated oxygen sensor has deteriorated. If it is
higher, it is assumed that the harness is damaged or
has a short circuit.
If the heated oxygen sensor signal voltage has not
changed even once (lean/rich) after the DTC was
erased, the sensor switch time will display as 0 sec-
onds.

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

• Left bank heated oxygen sensor (front) deterio-

rated.

• PCM failed.

AK201049

CONNECTOR: D-116

D-116

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-216

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check data list item 11:
Heated Oxygen Sensor Bank 2, Sensor 1 (left 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

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 : Replace the heated oxygen sensor (front). Then go to

Step 2.

STEP 2. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 4

− Heated Oxygen Sensor

Monitor

P.13Ab-2

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0153 set?

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

ACX01539

16-PIN

MB991502

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