Mitsubishi Montero (2004+). Manual — part 191

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-251

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 117) from the output terminal (terminal
No. 4) of the right bank heated oxygen sensor
(rear).

• Terminal No. 2 of the right bank heated oxygen

sensor (rear) is grounded with PCM (terminal No.
96).

.

TECHNICAL DESCRIPTION

• The output signal of the right bank heated oxygen

sensor (front) is compensated by the output sig-
nal of the right bank heated oxygen sensor (rear).

• The PCM checks for an open circuit in the right

bank heated oxygen sensor (rear) output line.

.

DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (rear) output volt-

age does not change during specified go/stop
operations including fuel cut are repeated.

.

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 heater (front) monitor

• Heated oxygen sensor heater (rear) 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

AK201275

CONNECTOR: C-14

C-14(GR)

AB

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

AK201049

D-14

AB

CONNECTOR: D-14

AK201049

CONNECTOR: D-116

D-116

AC

AK201038AF

CONNECTOR: D-135

PCM

D-135(GR)

AK201052

E-112

AB

CONNECTOR: E-112

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-252

• Barometric pressure sensor

.

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 76°C

(169

°F).

• The right bank heated oxygen sensor (front) is

active.

• The cumulative volume airflow sensor output fre-

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

• Repeat 3 or more times: drive

*1

, stop

*2

.

Drive

*1

:

• Engine speed is higher than 1,500 r/min.

• Volumetric efficiency is higher than 40 per-

cent.

• Vehicle speed is higher than 30 km/h (19

mph).

• A total of more than 10 seconds have

elapsed with the above mentioned condi-
tions, and more than 2 seconds have
elapsed with the fuel shut off.

Stop

*2

:

• Vehicle speed is lower than 1.5 km/h (1

mph).

Judgement Criteria

• Change in the output voltage of the right bank

heated oxygen sensor (rear) is lower than 0.313
volt.
NOTE: Monitoring stops after fuel has been shut
off for more than 38 seconds.

.

END

YES

NO

NO

NO

START

MONITORING

CONDITION

YES

MALFUNCTION

GOOD

F1: COUNTER OF A DRIVING STATE.
F2: COUNTER OF A STOP STATE.

OUTPUT VOLTAGE

CHANGE < 0.313 V

GO/STOP OPERATION

FOR SPECIFIED TIMES

YES

AK302936

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-253

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 (rear) failed.

• 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

• MB991316: Test Harness

STEP 1. 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).

(4) Warm up the engine.

• After increasing the output voltage 0.15 volt or more by

the engine revving, finish it. Then confirm that the output
voltage reduces to 0.15 volt or less within 3 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 (rear). Then go to

Step 2.

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-254

STEP 2. Check the right bank heated oxygen sensor (rear).

(1) Disconnect the right bank heated oxygen sensor (rear)

connector C-14 and connect test harness special tool
MB991316 to the connector on the right bank heated
oxygen sensor (rear) side.

(2) Warm up the engine until engine coolant temperature

reaches 80

°C (176°F) or higher.

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

speed of 4,500 r/min.

(4) Connect a digital voltage meter between terminal No. 2

(black clip of special tool) and terminal No. 4 (white clip of
special tool).

(5) While repeatedly revving the engine, measure the right

bank heated oxygen sensor (rear) output voltage.

Standard value: 0.6

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wire;

incorrect connection can damage the right bank heated
oxygen sensor (rear).

• Be careful the heater is broken when voltage of beyond

8 volts is applied to the right bank heated oxygen sen-
sor (rear) heater.
NOTE: If the sufficiently high temperature [of approximate
400

°

C(752

°

F) or more] is not reached although the right

bank heated oxygen sensor (rear) is normal, the output volt-
age would be possibly low although the rich air/fuel ratio.
Therefore, if the output voltage 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 right bank
heated oxygen sensor (rear) with the positive terminal and
the negative 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 right bank heated oxygen sensor (rear).

Then go to Step 4.

AK201276

1

2

3

4

CONNECTOR: C-14

C-14(GR)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MB991316

WHITE

BLACK

AN