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Mitsubishi Montero (2002-2004). Manual - part 623

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-189

STEP 12. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 6

− Other Monitor

P.13Ab-2

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0141 set?

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

DTC P0150: Heated Oxygen Sensor Circuit High Voltage (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)

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-190

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 or PCM (terminal
No. 96).

TECHNICAL DESCRIPTION

• The left bank heated oxygen sensor (front)

detects the concentration of oxygen in the
exhaust gas; it converts that data to voltage, and
sends it to the PCM.

• When the left bank heated oxygen sensor (front)

begins to deteriorate, the heated oxygen sensor
signal response deteriorates also.

• The PCM 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

• 3 minutes or more have passed since the starting

sequence was completed.

• Left 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.

• Monitoring time: 7 seconds.

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

AK201049

CONNECTOR: D-116

D-116

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-191

Judgment Criteria

• Input voltage supplied to the PCM interface circuit

is higher than 4.5 volts when 5 volts is applied to
the left bank heated oxygen sensor (front) output
line.

• The PCM monitors for this condition once during

the drive cycle.

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

• Left bank heated oxygen sensor (front) deterio-

rated.

• Open circuit in left bank heated oxygen sensor

(front) output line.

• Open circuit in left bank heated oxygen sensor

(front) ground line.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991502: Scan Tool (MUT-II)

• MB991316: Test Harness

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).

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

output voltage should be 0.6 to 1.0 volt.

• Warming up the engine. When the engine is idling, the

output 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.

ACX01539

16-PIN

MB991502

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-192

STEP 2. Measure the sensor output voltage at left bank
heated oxygen sensor (front) connector B-26 by
backprobing
(1) Do not disconnect the connector B-26.
(2) Start the engine and run at idle.

(3) Measure the voltage between terminal No. 4 and ground by

backprobing.

• Warming up the engine. When the engine is 2,500 r/min,

the output voltage should repeat 0 to 0.8 volt alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?

YES : Go to Step 3.
NO : Go to Step 7.

AK201278

CONNECTOR: B-26

B-26(GR)

HARNESS
CONNECTOR:
COMPONENT
SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01538

1 2

B-26 HARNESS
CONNECTOR:
HARNESS SIDE

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