Mitsubishi Galant (2004+). Manual - part 1176

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-397

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

No. 4) to the left bank heated oxygen sensor 
(rear) heater.

• The PCM (terminal No. 137) controls continuity to 

the left bank heated oxygen sensor (rear) heater 
by turning the power transistor in the PCM "ON" 
and "OFF".

.

BACKGROUND

• 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 (rear) current 

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

°C (68°F).

.

MONITOR EXECUTION
Continuous

.

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

AK303079

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

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-398

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

.

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 (rear) 

heater is on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgment Criteria

• The left bank heated oxygen sensor (rear) heater  

current has continued to be lower than 0.16 
ampere or higher than 5.0 ampere for 4 seconds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13B-5

.

.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 5.0A

AK302401

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-399

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

• Open or shorted left bank heated oxygen sensor 

(rear) heater circuit, or harness damage.

• Open circuit in left bank heated oxygen sensor 

(rear) heater.

• Connector damage.

• Left bank heated oxygen sensor (rear) failed.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991316: Test Harness

• MB991923: Power Plant ECU Check Harness

STEP 1. Check harness connector B-24 at the left bank 
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. 

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-400

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

(1) Disconnect left bank heated oxygen sensor (rear) connector 

B-24 and connect test harness special tool, MB991316, to 
the connector on the left bank heated oxygen (rear) sensor 
side.

(2) Measure the resistance between heated oxygen sensor 

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

Standard value: 11 

− 18 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 11 and 18 ohms [at 

20

°C (68°F)]?

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

Then go to Step 12.

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

AKX01624 AB

MB991316

HEATED
OXYGEN
SENSOR
EQUIPMENT
SIDE
CONNECTOR

BLUE

RED