Mitsubishi Galant 9G. Manual - part 1013

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-352

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal No. 

4) to the left bank heated oxygen sensor (front) 

heater.

• The PCM (terminal No. 125) controls continuity to 

the left bank heated oxygen sensor (front) 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

Left bank heated oxygen sensor heater (front) current 

is out of specified range when engine coolant tem-

perature 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

.

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

AK303014

CONNECTOR: B-17X

MFI RELAY

MFI RELAY

FRONT OF VEHICLE

B-17X

AB

AK303070

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

AB

AK303059

CONNECTOR: B-23

PCM

AB

AIR CLEANER

B-23

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-353

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 left bank heated oxygen sensor (front) 

heater is on.

• Battery positive voltage is at between 11 and 16.5 

volts.

Judgment Criteria

• The left bank heated oxygen sensor (front) heater 

current has continued to be lower than 0.16 
ampere or higher than 7.5 ampere for 4 seconds.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13B-6

.

.

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

• Open or shorted left bank heated oxygen sensor 

(front) heater circuit, or harness damage.

• Open circuit in left bank heated oxygen sensor 

(front) heater.

• Connector damage.

• PCM failed.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 7.5A

AK302400

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-354

DIAGNOSIS

Required Special Tools:

• MD998464: Test Harness

• MB991923: Check Harness

STEP 1. Check harness connector B-25 at the left bank 
heated oxygen sensor (front) 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.

AK303071

1

2

3

4

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-355

STEP 2. Check the left bank heated oxygen sensor (front).

(1) Disconnect left bank heated oxygen sensor (front) 

connector B-25 and connect test harness special tool, 
MD998464, to the connector on the left bank heated oxygen 
(front) sensor side.

(2) Measure the resistance between heated oxygen sensor 

connector terminal No. 1 (red clip) and terminal No. 3 (blue 
clip).

Standard value: 4.5 

− 8.0 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 4.5 and 8.0 ohms 

[at 20

°C (68°F)]?

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

Then go to Step 12.

AK303071

1

2

3

4

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624

HEATED
OXYGEN
SENSOR
EQUIPMENT
SIDE
CONNECTOR

MD998464

BLUE

RED

AC