Mitsubishi Galant (2004+). Manual - part 1164

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-349

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-350

STEP 3. Measure the power supply voltage at left bank 
heated oxygen sensor (front) harness side connector B-25.

(1) Disconnect the connector B-25 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 5.
NO :  Go to Step 4.

AK303071

1

2

3

4

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01498

B-25 HARNESS 
CONNECTOR: 
COMPONENT SIDE

1

2

3

4

BB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-351

STEP 4. Check harness connector B-17X at the MFI relay 
for damage.

Q: Is the harness connector in good condition?

YES : Repair harness wire between MFI relay connector 

B-17X (terminal No. 4) and left bank heated oxygen 
sensor (front) connector B-25 (terminal No. 1) 
because of open circuit or short circuit to ground. 
Then go to Step 12.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12. 

1

2

3

4

AK303017

CONNECTOR: B-17X

FRONT OF VEHICLE

B-17X

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

RELAY BOX

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-352

STEP 5. Meaure the power supply voltage at PCM 
connector B-23 by using power plant ECU check harness 
special tool MB991923.

(1) Disconnect the all PCM connectors and connect power 

plant ECU check harness special tool MB991923 between 
the separated connectors.

(2) Turn the ignition switch to the "ON" position.

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AK303058

HARNESS CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-23

B-23

PCM

AB

AIR CLEANER

AK202954

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140 139 138 137 136 135 134

146 145 144 143 142 141

153 152 151 150 149 148 147

AB

POWER PLANT ECU 
CHECK HARNESS CONNECTOR

MB991923

PCM