Mitsubishi Galant (2004+). Manual - part 1148

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-285

STEP 3. Check harness connector B-08 at right bank 
heated oxygen sensor (rear) and harness connector B-21, 
B-22 at PCM for damage.

Q: Is the harness connector in good condition?

YES : Replace the PCM.Then go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 4.

AK303064

1

2

3

4

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

CONNECTOR: B-08

B-08 (GR)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

AK303052

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

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

CONNECTORS: B-21, B-22

AB

B-21 HARNESS CONNECTOR: 
COMPONENT SIDE

B-22 HARNESS CONNECTOR: 
COMPONENT SIDE

PCM

AIR CLEANER

B-22 (B)

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-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.13B-5

.

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

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-287

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

TO PCM

TO PCM

RED-

WHITE

AK302843

RED-WHITE

BR

O

WN-BLA

CK

RIGHT BANK HEATED
OXYGEN SENSOR (REAR)

B-17X

1

2

3

4

BATTERY

1

3

2

4

138

MFI
RELAY

POWERTRAIN
CONTROL
MODULE (PCM)

4

3

1 2

B-08

MU802665

Right Bank Heated Oxygen Sensor (rear) Heater Circuit

B-23

RED-

WHITE

RED-

WHITE

1

2

3

4

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-288

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

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

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

the right bank 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
Right bank 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

.

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

AK303063

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

CONNECTOR: B-08

B-08 (GR)

AB

AK303059

CONNECTOR: B-23

PCM

AB

AIR CLEANER

B-23