Mitsubishi Galant (2004+). Manual — part 1159

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-329

STEP 2. Check for short circuit to power supply between
left bank heated oxygen sensor (front) connector B-25
(terminal No. 4) and PCM connector B-22 (terminal No. 91).

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.

AK303071

1

2

3

4

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

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-330

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.13B-5

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0152 set?

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

DTC P0153: Heated Oxygen Sensor Circuit Slow Response (bank 2, sensor 1)

BLA

CK

BLA

CK

TO PCM

FROM MFI RELAY

WHITE

AK302844

69

91

4

3

1

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

2

B-25

MU802605

B-22

Left Bank Heated Oxygen Sensor (front) Circuit

B-21

1

2

3

4

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-331

.

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 left bank heated oxygen sensor
(front).

• Terminal No. 2 of the left bank heated oxygen

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

.

TECHNICAL DESCRIPTION

• The left 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 left bank heated oxygen sensor (front)

begins to deteriorate, the left bank 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 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.

.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (front) rich/lean

switching frequency is under specified value.

.

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

.

AK303070

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

AB

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) <3.8L ENGINE>

13B-332

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 50°C

(122

°F).

• Engine speed is between 1,250 and 3,000 r/min.

• Volumetric efficiency is between 18 and 60 per-

cent.

• Under the closed loop air/fuel control.

• The accelerator pedal open.

• Short-term fuel trim is at between −30 and +25

percent.

• More than 3 seconds have elapsed after the

abovementioned conditions have been met.

Judgment Criteria

• The left bank heated oxygen sensor (front) sends

"lean" and "rich" signals alternately 13 times or
less for 12 seconds.

NOTE: If the sensor switching frequency is lower
than the Judgment Criteria due to the MUT-III OBD-II
test Mode

−

H02S Test Results, it is assumed that

the heated oxygen sensor has deteriorated. If it is
higher, it is assumed that the harness is damaged or
has a short circuit.
If the heated oxygen sensor signal voltage has not
changed even once (lean/rich) after the DTC was
erased, the sensor switch time will display as 0 sec-
onds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 4

− Heated Oxygen Sensor Monitor

P.13B-5

.

.

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

• Left bank heated oxygen sensor (front) deterio-

rated.

• Connector damage.

• PCM failed.

F0: THRESHOLD VALUE FOR AVERAGE SWITDHING FREQUENCY

START

MONITORING

CONDITIONS

MALFUNCTION

GOOD

END

NO

NO

YES

YES

Ff < F0

CALCULATE AVERAGE SWITCHING

FREQUENCY (Ff) OVER SPECIFIED TIMES

AK302395