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Mitsubishi Montero (2002-2004). Manual - part 676

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-401

STEP 6. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

(2) Read the diagnostic trouble code.
Q: Is DTC P0421 set?

YES : Replace the PCM. Then go to Step 7.
NO : The inspection is complete.

STEP 7. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0421 set?

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

DTC P0431: Warm up catalyst Efficiency Below Threshold (bank 2)

TECHNICAL DESCRIPTION

• The signal from the rear heated oxygen sensor

differs from the front heated oxygen sensor. That
is because the catalytic converter purifies
exhaust gas. When the catalytic converter has
deteriorated, the signal from the front heated oxy-
gen sensor becomes similar to the rear heated
oxygen sensor.

• The PCM compares the output of the front and

rear heated oxygen sensor signals.

DTC SET CONDITIONS

Check Conditions

• Engine speed is lower than 3,000 r/min.

• The throttle valve is open.

• Volume airflow sensor output frequency is

between 69 and 169 Hz.

• More than 3 seconds has elapsed after the

above-mentioned three conditions have been
met.

• Intake air temperature is higher than −10°C

(14

°F).

• Barometric pressure is higher than 76 kPa (11

psi).

• Under the closed loop air/fuel ratio control.

• Vehicle speed is 1.5 km/h (0.93 mph) or more.

• The PCM monitors for this condition for 7 cycles

of 12 seconds each during the drive cycle.

• Short-term fuel trim is higher than −30 percent

and lower than +25 percent.

• The cumulative volume airflow sensor output fre-

quency for every 2 seconds is higher than 4,000
Hz.

Judgment Criteria

• The left bank heated oxygen sensor (rear) signal

frequency divided by left bank heated oxygen
sensor (front) signal frequency = 0.75 or more.

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

• Left bank side catalytic converter deteriorated.

• Left bank heated oxygen sensor failed.

• PCM failed.

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-402

STEP 1. Check the exhaust leaks.
Q: Are there any abnormalities?

YES : Go to Step 2.
NO : Repair it. Then go to Step 7.

STEP 2. Using scan tool MB991502, check data list item 59:
Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).

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

59, Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).

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

output voltage should repeat 0 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 : Go to Step 3.
NO : Refer to DTC P0156

− Heated Oxygen Sensor Circuit

(Bank 2, Sensor 2)

P.13Ac-235

, DTC P0157

− Heated

Oxygen Sensor Circuit Low Voltage (Bank 2, Sensor
2)

P.13Ac-250

, DTC P0158

− Heated Oxygen Sensor

Circuit High Voltage (Bank 2, Sensor 2)

P.13Ac-256

DTC P0159

− Heated Oxygen Sensor Circuit Slow

Response (Bank 2, Sensor 2)

P.13Ac-260

STEP 3. Using scan tool MB991502, check data list item 11:
Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
(1) Start the engine and run at idle.
(2) 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.

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

YES : Go to Step 4.
NO : Refer to DTC P0150

− Heated Oxygen Sensor Circuit

(Bank 2, Sensor 1)

P.13Ac-189

, DTC P0151

− Heated

Oxygen Sensor Circuit Low Voltage (Bank 2, Sensor
1)

P.13Ac-204

, DTC P0152

− Heated Oxygen Sensor

Circuit High Voltage (Bank 2, Sensor 1)

P.13Ac-210

DTC P0153

− Heated Oxygen Sensor Circuit Slow

Response (Bank 2, Sensor 1)

P.13Ac-214

, DTC

P0154

− Heated Oxygen Sensor Circuit No Activity

Detected (Bank 2, Sensor 1)

P.13Ac-217

ACX01539

16-PIN

MB991502

ACX01539

16-PIN

MB991502

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-403

STEP 4. Using scan tool MB991502, check data list item 11:
Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991502 to the data reading mode for item

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

(3) Keep the engine speed at 2,000 r/min.

• 0 − 0.4 and 0.6 − 1.0 volt should alternate 15 times or

more within 10 seconds.

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

YES : Go to Step 5.
NO : Replace the left bank heated oxygen sensor (front).

Then go to Step 7.

STEP 5. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

(2) Read the diagnostic trouble code.
Q: Is DTC P0431 set?

YES : Replace the left bank side catalytic converter. Then

go to Step 6.

NO : The inspection is complete.

STEP 6. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

(2) Read the diagnostic trouble code.
Q: Is DTC P0431 set?

YES : Replace the PCM. Then go to Step 7.
NO : The inspection is complete.

STEP 7. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0431 set?

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

ACX01539

16-PIN

MB991502

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-404

DTC P0441: Evaporative Emission System Incorrect Purge Flow

TECHNICAL DESCRIPTION

• PCM detects stuck open of evaporative emission

purge solenoid valve and stuck close of evapora-
tive emission ventilation solenoid valve by pres-
sure change in fuel tank.

• Stuck open of evaporative emission purge sole-

noid valve is judged through monitoring leak of
evaporative emission system.

• Stuck close of evaporative emission ventilation

solenoid valve is judged after 20 seconds of end
of monitoring leak of evaporative emission sys-
tem, or of usual operation of evaporative emis-
sion purge solenoid from ON to OFF.

DTC SET CONDITIONS

Check Conditions

• ON duty cycle of the evaporative emission purge

solenoid is 0 percent.

• 20 seconds have elapsed from the time the duty

cycle of the evaporative emission purge solenoid
has turned to 0 percent.

Judgment Criteria

• The pressure in the fuel tank is −2 kPa (0.29 psi)

or less for 0.1 second.

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

• Evaporative emission purge solenoid failed.

• Evaporative emission ventilation solenoid failed.

• Choking up of hose between evaporative emis-

sion canister and evaporative emission ventila-
tion solenoid.

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, read the diagnostic
trouble code (DTC).

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) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P0451 set?

YES : Refer to, DTC P0451 - Evaporative Emission System

Pressure Sensor Range/Performance

P.13Ac-436

NO : Go to Step 2.

AK200968

EVAPORATIVE
EMISSION PURGE
SOLENOID

B-06(B)

CONNECTOR: B-06

AK201059

G-27(B)

CONNECTOR: G-27

ACX01539

16-PIN

MB991502

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