Mitsubishi Galant 9G. Manual — part 709

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-278

STEP 1. Check harness connector B-38 at cylinder 1, 4
heated oxygen sensor (rear) and harness connector B-22
at PCM 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 3.

AK303826

1

2

3

4

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-38

B-38 (B)

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

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) <2.4L ENGINE>

13A-279

STEP 2. Check for short circuit to power supply between
cylinder 1, 4 heated oxygen sensor (rear) connector B-38
(terminal No. 4) and PCM connector B-22 (terminal No. 97).
Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 3.
NO : Repair it. Then go to Step 3.

AK303826

1

2

3

4

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-38

B-38 (B)

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

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) <2.4L ENGINE>

13A-280

STEP 3. 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 6 −

Other Monitor

P.13A-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0138 set?

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

DTC P0139: Cylinder 1, 4 Heated Oxygen Sensor Circuit Slow Responce (sensor 2)

52

51

53 54 55 56

57

58 59 60 61 62

63

64 65 66 67 68 69

70

71 72 73 74 75

76

77 78 79 80 81 82

83

100

99

92

91

93 94 95

96 97 98

101 102 103 104

105 106 107 108

109 110 111 112 113

AK303824

1

2

3

4

YELLO

W

BLUE

BLA

CK

BLA

CK

TO PCM

FROM MFI RELAY

69

97

2

4

3

1

B-22

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

POWERTRAIN CONTROL
MODULE (PCM)

B-38

MU802605

Cylinder 1, 4 Heated Oxygen Sensor (rear) Circuit

B-21

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-281

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 97) from the output terminal (terminal
No. 4) of the cylinder 1, 4 heated oxygen sensor
(rear).

• Terminal No. 2 of the cylinder 1, 4 heated oxygen

sensor (rear) is grounded with PCM (terminal No.
69).

.

TECHNICAL DESCRIPTION

• The output signal of the cylinder 1, 4 heated oxy-

gen sensor (front) is compensated by the output
signal of the cylinder 1, 4 heated oxygen sensor
(rear).

• The PCM checks for an open circuit in the cylin-

der 1, 4 heated oxygen sensor (rear) output line.

.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 1, 4 heated oxygen sensor (rear) output

voltage does not change during specified go/stop
operations including fuel cut are repeated.

.

MONITOR EXECUTION

Continuous

.

MONITOR EXECUTION CONDITIONS
(Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Heated oxygen sensor heater (front) monitor

• Heated oxygen sensor heater (rear) monitor

• Air/fuel ratio feedback monitor

Sensor (The sensor below is determined to be

normal)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

.

AK303825AB

CONNECTOR: B-38

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (REAR)

B-38 (B)

AK303013

CONNECTORS: B-21, B-22

PCM

AB

AIR CLEANER

B-22 (B)

B-21 (B)