Mitsubishi Galant (2004+). Manual - part 1128

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-205

STEP 13. Check for short circuit to ground and harness 
damage between right bank heated oxygen sensor (front) 
connector B-09 (terminal No. 4) and PCM connector B-22 
(terminal No. 92).
Q: Is the harness wire in good condition?

YES : Go to Step 14.
NO :  Repair it. Then go to Step 15.

1

2

3

4

AK303048

B-09 (B)

CONNECTOR: B-09

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

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) <3.8L ENGINE>

13B-206

STEP 14. Check the right bank heated oxygen sensor 
(front).
(1) Disconnect the right bank heated oxygen sensor (front) 

connector B-09 and connect test harness special tool, 
MD998464, to the connector on the right bank heated 
oxygen sensor (front) side.

(2) Warm up the engine until engine coolant temperature 

reaches 80

°C (176°F) or higher.

(3) Perform a tracing for 5 minutes or more with the engine 

speed of 4,500 r/min.

(4) Connect a digital voltage meter between terminal No. 2 

(black clip) and terminal No. 4 (white clip).

(5) While repeatedly revving the engine, measure the right 

bank heated oxygen sensor (front) output voltage.

Standard value: 0.6 

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wire; 

incorrect connection can damage the oxygen sensor.

• Be careful the heater is broken when voltage of beyond 

8V is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate 
400

°

C or more) is not reached although the oxygen sensor 

is normal, the output voltage would be possibly low 
although the rich air-fuel ratio. Therefore, if the output volt-
age is low, use a jumper wire to connect the terminal No.1 
(red clip of special tool) and the terminal No. 3 (blue clip of 
special tool) of the oxygen sensor with a (+) terminal and (-) 
terminal of 8 V power supply respectively, then check again.

Q: Is the voltage between 0.6 and 1.0 volt?

YES : Replace the PCM. Then go to Step 15.
NO :  Replace the right bank heated oxygen sensor (front). 

Then go to Step 15.

1

2

3

4

AK303048

B-09 (B)

CONNECTOR: B-09

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MD998464

WHITE

BLACK

AQ

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-207

STEP 15. 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.13B-5

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0130 set?

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

DTC P0131: Heated Oxygen Sensor Circuit Low Voltage (bank 1, sensor 1)

BLUE

BLA

CK

TO PCM

FROM MFI RELAY

PINK

AK302839

69

92

4

3

1

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

1 2

4

3

B-09

MU802605

2

B-22

Right Bank Heated Oxygen Sensor (front) Circuit

B-21

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-208

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 92) from the output terminal (terminal 
No. 4) of the right bank heated oxygen sensor 
(front).

• Terminal No. 2 of the right bank heated oxygen 

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

.

TECHNICAL DESCRIPTION

• The right bank 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 right bank 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 right bank heated oxygen 
sensor (front). In addition, the PCM also checks 
for an open circuit in the right bank heated oxy-
gen sensor (front) output line.

.

DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (front) output volt-

age stays low when air/fuel ratio is forced to be 
rich. The above procedure is repeated when oxy-
gen 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

.

AK303047

B-09 (B)

CONNECTOR: B-09

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AB

AK303013

CONNECTORS: B-21, B-22

PCM

AB

AIR CLEANER

B-22 (B)

B-21 (B)