Mitsubishi Galant 9G. Manual - part 714

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-298

STEP 11. Check the trouble symptoms.
(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 P0141 set?

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 

− How to 

Cope with Intermittent Malfunctions 

P.00-14

. 

STEP 12. 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 P0141 set?

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

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DTC P0150: Cylinder 2, 3 Heated Oxygen Sensor Circuit (sensor 1)

100

99

92

91

93 94 95

96 97 98

101 102 103 104

105 106 107 108

109 110 111 112 113

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

AK303828

1

2

3

4

BLA

CK

BLA

CK

TO PCM

FROM MFI RELAY

WHITE

69

91

4

3

1

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

B-36

MU802665

2

B-22

Cylinder 2, 3 Heated Oxygen Sensor (front) Circuit

B-21

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-300

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 91) from the output terminal (terminal 
No. 4) of the cylinder 2, 3 heated oxygen sensor 
(front).

• Terminal No. 2 of the cylinder 2, 3 heated oxygen 

sensor (front) is grounded with or PCM (terminal 
No. 69).

.

TECHNICAL DESCRIPTION

• The cylinder 2, 3 heated oxygen sensor (front) 

detects the concentration of oxygen in the 
exhaust gas; it converts those data to voltage, 
and inputs the resulting signals to the PCM.

• When the cylinder 2, 3 heated oxygen sensor 

(front) begins to deteriorate, the heated oxygen 
sensor signal response becomes poor.

• The PCM forcibly varies the air/fuel mixture to 

make it leaner and richer, and checks the 
response speed of the cylinder 2, 3 heated oxy-
gen sensor (front). In addition, the PCM also 
checks for an open circuit in the cylinder 2, 3 
heated oxygen sensor (front) output line.

.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 2, 3 heated oxygen sensor (front) circuit is 

switched to 5 volts intentionally when oxygen 
sensor output is low, and detects the malfunction 
if the output voltage changes to equal or greater 
than 4.5 volts. The above procedure is repeated 
when oxygen sensor is inactive.

.

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

• Misfire monitor

• Fuel system monitor

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

• Accelerator pedal position sensor

.

AK303829AB

CONNECTOR: B-36 

B-36 (GR)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (FRONT)

AK303013

CONNECTORS: B-21, B-22

PCM

AB

AIR CLEANER

B-22 (B)

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-301

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• 3 minutes or more have passed since the engine 

starting sequence was completed.

• Cylinder 2, 3 heated oxygen sensor (front) signal 

voltage has continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C 

(169

°F).

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

• Volumetric efficiency is higher than 25 percent.

• Monitoring time: 7 seconds.

START

V

F

 > =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK401409

V

F

 < 0.2V

8secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH