Mitsubishi Montero Sport (2004+). Manual - part 198

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-205

MONITOR EXECUTION CONDITIONS (Other 
monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Heated oxygen sensor heater (front) monitor

• Misfire monitor

• Fuel system 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

.

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 50°C 

(122

°F).

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

r/min.

• Under the closed loop air/fuel control.

• Volumetric efficiency is at between 25 and 60 

percent.

• Short-term fuel trim is higher than −30 and lower 

than +25 percent.

• More than 3 seconds have elapsed after the 

above mentioned conditions have been met.

• The PCM monitors for this condition for 7 cycles 

of 12 seconds each during the drive cycle.

• The throttle valve is open.

F1: THRESHOLD VALUE FOR REAL-TIME SWITDHING FREQUENCY
F0: THRESHOLD VALUE FOR AVERAGE SWITDHING FREQUENCY

START

MONITORING

CONDITIONS

MALFUNCTION

GOOD

END

NO

NO

YES

YES

Ff < F0

CALCULATE AVERAGE SWITCHING

FREQUENCY (Ff) OVER SPECIFIED TIMES

AK301438

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-206

Judgment Criteria

• The right bank heated oxygen sensor (front) 

sends "lean" and "rich" signals alternately 11 
times or less for 12 seconds.
NOTE: If the sensor switch time is longer than the 
Judgment Criteria due to the MUT-III OBD-II test 
Mode 

−

 H02S Test Results, it is assumed that the 

heated oxygen sensor has deteriorated. If it is 
short, 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 seconds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 4 

− Heated Oxygen Sensor Monitor 

P.13A-4

.

.

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

• Right bank heated oxygen sensor (front) deterio-

rated.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

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

• MB991824: V.C.I

• MB991827: USB Cable

• MB991911: Main Harness B

• MD998464: Test Harness

STEP 1. Using scan tool MB991958, check data list item 39: 
Heated Oxygen Sensor (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 

39, Heated Oxygen Sensor (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 INTRODUCTION, How to Use 
Troubleshooting/Inspection Service Points 

P.00-7

.

NO :  Go to Step 2.

AK303629AB

MB991911

MB991827

MB991824 

16-PIN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-207

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

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

(2) Warm up the engine until engine coolant temperature 

reaches 80

°C (176°F) or higher.

(3) Perform a tracing for 5 minutes or more with the engine 

speed of 4,500 r/min.

(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 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 oxygen sensor.

• Be careful the heater is broken when voltage of beyond 

8 volts is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate 
400

°

C or more) is not reached although the oxygen sensor 

is normal, the output voltage would be possibly low 
although the rich air-fuel ratio. Therefore, if the output volt-
age 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 oxygen sensor with a (+) terminal and (-) 
terminal of 8 volts power supply respectively, then check 
again.

Q: Is the voltage between 0.6 and 1.0 volt?

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

Step 4.

AK200490

1

2

3

4

A-07(B)

AB

CONNECTOR: A-07

HARNESS 
CONNECTOR: 
COMPONENT SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MD998464

WHITE

BLACK

AL

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-208

STEP 3. Check harness connector A-07 at heated oxygen 
sensor (front) and harness connector C-90, C-91 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 P0133 set?

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

AK200490

1

2

3

4

A-07(B)

AB

CONNECTOR: A-07

HARNESS 
CONNECTOR: 
COMPONENT SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK104029

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41

98

78

71

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91

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92

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AB

CONNECTORS: C-90, C-91

C-90(GR) C-91(GR)

C-90 HARNESS CONNECTOR:
COMPONENT SIDE

C-91 HARNESS CONNECTOR:
COMPONENT SIDE