Mitsubishi Galant. Manual — part 231

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-149

STEP 9. Check for harness damage between MFI relay
connector A-21X terminal 1 and right bank heated oxygen
sensor (rear) connector B-31 terminal 1.
Q: Is the harness wire in good condition?

YES : Go to Step 10.
NO : Repair it. Then go to Step 12.

STEP 10. Check for harness damage between right bank
heated oxygen sensor (rear) connector B-31 terminal 3 and
PCM connector C-39 terminal 27.
Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO : Repair it. Then go to Step 12.

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000617

CONNECTOR:B-33

AB

AK000617

CONNECTOR:B-33

AB

AK000280

CONNECTOR : C-39

PCM

AW

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-150

STEP 11. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to,

Procedure 6

−

Other Monitor(

P.13B-4

).

(2) Check the diagnostic trouble code (DTC).

Q: Is the DTC P0141 is output?

YES : Replace the PCM. Then go to Step 12.
NO : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points(

P.00-8

).

STEP 12. Test the OBD- II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to,

Procedure 6

−

Other Monitor(

P.13B-4

).

(2) Check the diagnostic trouble code (DTC).

Q: Is the DTC P0141 is output?

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

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-151

DTC P0150: O

2

Sensor Circuit Malfunction (bank 2 sensor 1)

AK000505

4

1 2
3

BLA

CK

BLA

CK

WHITE

B-28
MU802605

POWERTRAIN CONTROL
MODULE(PCM)

LEFT BANK HEATED OXYGEN
SENSOR(FRONT)

FROM MFI RELAY

TO ECM
OR PCM

1

2

3

4

57

71

98

78

71

88 89

76 77

72
79
91

73
80

74

75

81
92

82 83
93

84 85

94

86 87

95 96

90

97

C-41
(MU803782)

C-40
(MU803781)

42 43
48 49 50 51 52 53 54 55 56 57

46

45

44

58 59

60 61 62 63

64 65 66

47

41

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-152

CIRCUIT OPERATION

•

A voltage corresponding to the oxygen
concentration in the exhaust gas is sent to the
PCM (terminal 71) from the output terminal
(terminal 4) of the left bank heated oxygen sensor
(front).

•

Terminal 2 of the left bank heated oxygen sensor
(front) is grounded with PCM (terminal 57).

TECHNICAL DESCRIPTION

•

The left bank heated oxygen sensor (front)
detects the concentration of oxygen in the
exhaust gas; it converts that data to voltage, and
sends it to the PCM.

•

When the left bank heated oxygen sensor (front)
begins to deteriorate, the heated oxygen sensor
signal response deteriorates also.

•

The PCM varies the air/fuel mixture to make it
leaner and richer, and checks the response
speed of the left bank heated oxygen sensor
(front). In addition, the PCM also checks for an
open circuit in the left bank heated oxygen sensor
(front) output line.

DTC SET CONDITIONS

Check Conditions

•

Left bank heated oxygen sensor (front) signal
voltage has continued to be 0.2 volt or lower for
three minutes or more after engine starting
sequence was completed.

•

Engine coolant temperature is higher than 82

°

C

(180

°

F).

•

Engine speed is higher than 1,200 r/min.

•

Volumetric efficiency is higher than 25 percent.

•

Monitoring time: 7 seconds.

Judgment Criteria

•

Input voltage supplied to the PCM interface
circuit is higher than 4.5 volts when 5 volts is
applied to the left bank heated oxygen sensor
(front) output line via a resistor.

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

•

Left bank heated oxygen sensor (front)
deteriorated.

•

Open circuit in left bank heated oxygen sensor
(front) output line.

•

Open circuit in left bank heated oxygen sensor
(front) ground line.

•

PCM failed.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)
MD998464: Test Harness

ACX02489 AF

CONNECTOR:B-28

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK000280

CONNECTORS : C-40, C-41

C-41

C-40

PCM

AX