Mitsubishi Galant 9G. Manual — part 708

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-274

STEP 4. Check for short circuit to ground 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 5.
NO : Repair it. Then go to Step 5.

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-275

STEP 5. 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 P0137 set?

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

DTC P0138: Cylinder 1, 4 Heated Oxygen Sensor Circuit High Voltage (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-276

.

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 is over specified range.

.

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)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-277

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• 2 seconds or more have passed since the engine

starting sequence was completed.

Judgment Criteria

• Cylinder 1, 4 heated oxygen sensor (rear) output

voltage has continued to be 1.2 volts or higher for
2 seconds.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-6

.

.

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

• Short circuit in cylinder 1, 4 heated oxygen sen-

sor (rear) output line.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

START

END

NO

NO

YES

YES

MALFUNCTION

GOOD

2secs HAVE PASSED?

OUTPUT VOLTAGE > 1.2V

NO

YES

MONITORING

CONDITIONS

AK302026