Mitsubishi Montero Sport (2004+). Manual — part 271

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-497

STEP 2. Using scan tool MB991958, check data list item 69:
Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).

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

69, Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).

• Warm 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 P0136

− Heated Oxygen Sensor Circuit

(bank 1, sensor 2)

P.13A-243

, DTC P0137

− Heated

Oxygen Sensor Circuit low voltage (bank 1, sensor 2)

P.13A-243

, DTC P0138

− Heated Oxygen Sensor

Circuit High Voltage (bank 1, sensor 2)

P.13A-252

,

DTC P0139

− Heated Oxygen Sensor Circuit Slow

Response (bank 1, sensor 2)

P.13A-258

.

STEP 3. Using scan tool MB991958, check data list item 39:
Heated Oxygen Sensor Bank 1, Sensor 1 (right front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 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.

(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 P0130

− Heated Oxygen Sensor Circuit

(bank 1, sensor 1)

P.13A-178

, DTC P0131

− Heated

Oxygen Sensor Circuit low voltage (bank 1, sensor 1)

P.13A-190

, DTC P0132

− Heated Oxygen Sensor

Circuit High Voltage (bank 1, sensor 1)

P.13A-198

,

DTC P0133

− Heated Oxygen Sensor Circuit Slow

Response (bank 1, sensor 1)

P.13A-203

, DTC P0134

− Heated Oxygen Sensor No Activity Detected (bank

1, sensor 1)

P.13A-209

.

AK303629AB

MB991911

MB991827

MB991824

16-PIN

AK303629AB

MB991911

MB991827

MB991824

16-PIN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-498

STEP 4. Using scan tool MB991958, check data list item 39:
Heated Oxygen Sensor Bank 1, Sensor 1 (right front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item

39, Heated Oxygen Sensor Bank 1, Sensor 1 (right 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 right 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

Diagnostic Function

− OBD-II Drive Cycle − Procedure 3 −

Catalytic Converter Monitor

P.13A-4

.

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

YES : Replace the right bank side catalytic converter. Then

go to Step 6.

NO : The procedure is complete.

STEP 6. 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 3 −

Catalytic Converter Monitor

P.13A-4

.

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

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

STEP 7. 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 3 −

Catalytic Converter Monitor

P.13A-4

.

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

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

AK303629AB

MB991911

MB991827

MB991824

16-PIN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-499

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.

.

DESCRIPTIONS OF MONITOR METHODS
Front and rear oxygen sensor rich/lean switching fre-

quencies are nearly equal.

.

MONITOR EXECUTION
Continuous

.

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 (front) monitor

• Heated oxygen sensor (rear) monitor

• Heated oxygen sensor heater (front) monitor

• Heated oxygen sensor heater (rear) monitor

• Misfire monitor

• Fuel system monitor

• Air/fuel ratio feedback 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

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-500

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

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

• Volume airflow sensor output frequency is

between 69 and 169 Hz.

• Intake air temperature is higher than −10°C

(14

°F).

• Barometric pressure is higher than 76 kPa (22.4

in.Hg).

• The throttle valve is open.

• 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 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.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 3

− Catalytic Converter Monitor

P.13A-4

.

.

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.

• Exhaust leaks.

• PCM failed.

START

MONITORING

CONDITIONS

Rf > R0

MALFUNCTION

GOOD

END

NO

NO

YES

YES

CALCULATE AVERAGE FREQUENCY

RATIO (Rf = Fr/Ff) OF SPECIFIED TIMES

R0: AVERAGE THRESHOLD VALUE.
R1: REAL TIME THRESHOLD VALUE.

AK204058