Mitsubishi Montero (2004+). Manual — part 209

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-323

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CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 116) from the output terminal (terminal
No. 4) of the left bank heated oxygen sensor
(rear).

• Terminal No. 2 of the left bank heated oxygen

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

.

TECHNICAL DESCRIPTION

• The output signal of the left bank heated oxygen

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

• The PCM checks for an open circuit in the left

bank heated oxygen sensor (rear) output line.

.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (rear) circuit is

switched to 5 volts intentionally when oxygen
sensor output is low, and detects the malfunction
if the output voltage changes to equal or greater
than 4.5 volts. The above procedure is repeated
when oxygen sensor is inactive.

.

MONITOR EXECUTION
Continuous

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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

AK201279

CONNECTOR: C-15

C-15(B)

AD

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

AK201049

CONNECTOR: D-116

D-116

AC

AK201049

D-14

AB

CONNECTOR: D-14

AK201038AF

CONNECTOR: D-135

PCM

D-135(GR)

AK201052

E-112

AB

CONNECTOR: E-112

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-324

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

.

DTC SET CONDITIONS

Logic Flow Chart

START

V

F

> =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK302935

V

F

< 0.15V

10secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-325

Check Conditions

• 3 minutes or more have passed since the engine

starting sequence was completed.

• Left bank heated oxygen sensor (rear) signal

voltage has continued to be 0.15 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.

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 (rear) output
line via a resistor.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-4

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

• Left bank heated oxygen sensor (rear) failed.

• Short circuit in left bank heated oxygen sensor

(rear) output line or harness damage.

• Open circuit in left bank heated oxygen sensor

(rear) ground line or harness damage.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assemb]y)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MD998464: Test Harness

STEP 1. Using scan tool MB991958, check data list item 59:
Left Bank Heated Oxygen Sensor Bank 2, Sensor 2 (left
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

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 : 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.

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-326

STEP 2. Measure the sensor output voltage at left bank
heated oxygen sensor (rear) connector C-15 by
backprobing.

(1) Do not disconnect the connector C-15.
(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 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 voltage normal?

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

AK201280

1

2

3

4

CONNECTOR: C-15

C-15(B)

AC

HARNESS
CONNECTOR:
COMPONENT SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

AKX01541

1 2

4

3

AV

C-15 HARNESS
CONNECTOR:
HARNESS SIDE