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Mitsubishi Galant 9G. Manual - part 711

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-286

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-6

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0139 set?

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

DTC P0141: Cylinder 1, 4 Heated Oxygen Sensor Heater Circuit (sensor 2)

121 122 123 124 125 126 127

128 129 130 131 132 133

134 135 136 137 138 139 140

141 142 143 144 145 146

147 148 149 150 151 152 153

AK400880

RED-

WHITE

RED

RED-WHITE

WN-BLA

CYLINDER 1, 4 HEATED

OXYGEN SENSOR (REAR)

B-17X

BATTERY

138

MFI
RELAY

B-38

MU802605

POWERTRAIN
CONTROL
MODULE (PCM)

Cylinder 1, 4 Heated Oxygen Sensor (rear) Heater Circuit

B-23

RED-

WHITE

TO PCM

TO PCM TO PCM

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-287

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal

No. 4) to the cylinder 1, 4 heated oxygen sensor
(rear) heater.

• The PCM (terminal No. 138) controls continuity to

the cylinder 1, 4 heated oxygen sensor (rear)
heater by turning the power transistor in the PCM
"ON" and "OFF".

TECHNICAL DESCRIPTION

• The PCM checks whether the heater current is

within a specified range when the heater is ener-
gized.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 1, 4 heated oxygen sensor heater (rear) cur-

rent is out of specified range when engine coolant
temperature is over 20

°C (68°F).

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)

• Not applicable

Sensor (The sensor below is determined to be

normal)

• Engine coolant temperature sensor

AK303803AB

CONNECTOR: B-17X

MFI RELAY

B-17X

AK303825AB

CONNECTOR: B-38

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

B-38 (B)

AK303059

CONNECTOR: B-23

PCM

AIR CLEANER

B-23

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-288

DTC SET CONDITIONS
Logic Flow Chart

Check Conditions

• 60 seconds have elapsed from the start of the

previous monitoring.

• Engine coolant temperature is higher than 20°C

(68

°F).

• While the cylinder 1, 4 heated oxygen sensor

(rear) heater is on.

• Battery positive voltage is between 11 and 16.5

volts.

Judgment Criteria

• The cylinder 1, 4 heated oxygen sensor (rear)

heater current has continued to be lower than
0.16 ampere or higher than 5.0 ampere for 4 sec-
onds.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-6

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

• Open or shorted cylinder 1, 4 heated oxygen sen-

sor (rear) heater circuit, or harness damage.

• Open circuit in cylinder 1, 4 heated oxygen sen-

sor (rear) heater.

• Cylinder 1, 4 heated oxygen sensor (rear) failed.

• Connector damage.

• PCM failed.

START

END

YES

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 5.0A

AK302027

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-289

DIAGNOSIS

Required Special Tools:

• MD998464: Test Harness

• MB991923: Power Plant ECU Check Harness

STEP 1. Check harness connector B-38 at the cylinder 1, 4
heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 2.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 12.

AK303826

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-38

B-38 (B)

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

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