Mitsubishi Galant (2004+). Manual - part 1170

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-373

STEP 11. Check harness connector B-21 at PCM for 
damage.

Q: Is the harness connector in good condition?

YES : Go to Step 12.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 15. 

AK303018

55

56

54 53 52 51

57

62 61 60 59 58

63

69 68 67 66 65 64

70

75 74 73 72 71

76

82 81 80 79 78 77

83

CONNECTOR: B-21

PCM

AB

HARNESS CONNECTOR: 
COMPONENT SIDE

AIR CLEANER

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-374

STEP 12. Check for harness damage between left bank 
heated oxygen sensor (rear) connector B-24 (terminal No. 
2) and PCM connector B-21 (terminal No. 69).

Q: Is the harness wire in good condition?

YES : Go to Step 13.
NO :  Repair it. Then go to Step 15.

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

AK303018

55

56

54 53 52 51

57

62 61 60 59 58

63

69 68 67 66 65 64

70

75 74 73 72 71

76

82 81 80 79 78 77

83

CONNECTOR: B-21

PCM

AB

HARNESS CONNECTOR: 
COMPONENT SIDE

AIR CLEANER

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-375

STEP 13. Check for short circuit to ground and harness 
damage between left bank heated oxygen sensor (rear) 
connector B-24 (terminal No. 4) and PCM connector B-22 
(terminal No. 96).

Q: Is the harness wire in good condition?

YES : Go to Step 14.
NO :  Repair it. Then go to Step 15.

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

AK303016

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

CONNECTOR: B-22

B-22 (B)

PCM

AB

HARNESS CONNECTOR: 
COMPONENT SIDE

AIR CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-376

STEP 14. Check the left bank heated oxygen sensor (rear).

(1) Disconnect the 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 
sensor (front) side.

(2) Warm up the engine until engine coolant 80

°C (176°F) or 

higher.

(3) Perform a tracing for 5 minutes or more with the engine 

speed of 4,500 r/min.

(4) Connect a digital volt meter between terminal No. 2 (black 

clip) and terminal No. 4 (white clip).

(5) While repeatedly revving the engine, measure the left bank 

heated oxygen sensor (rear) output voltage.

Standard value: 0.6 

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wire; 

incorrect connection can damage the oxygen sensor.

• Be careful the heater is broken when voltage of beyond 

8V is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate 
400

°

C or more) is not reached although the oxygen sensor 

is normal, the output voltage would be possibly low 
although the rich air-fuel ratio. Therefore, if the output volt-
age is low, use a jumper wire to connect the terminal No.1 
(red clip of special tool) and the terminal No. 3 (blue clip of 
special tool) of the oxygen sensor with a (+) terminal and (-) 
terminal of 8 V power supply respectively, then check again.

Q: Is the voltage between 0.6 and 1.0 volt?

YES : Replace the PCM. Then go to Step 15.
NO :  Replace the left bank heated oxygen sensor (rear). 

Then go to Step 15.

1

2

3

4

AK303079

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-24

AB

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

B-24 (GR)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MB991316

WHITE

BLACK

AN