Mitsubishi Galant 9G. Manual - part 981

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-224

STEP 2. Check for short circuit to power supply 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 : Replace the PCM. Then go to Step 3.
NO : Repair it. Then go to Step 3.

AK303048

B-09 (B)

CONNECTOR: B-09

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

HARNESS
CONNECTOR:
COMPONENT SIDE

AK303016

104

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

HARNESS CONNECTOR:
COMPONENT SIDE

AIR CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-225

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-6

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0132 set?

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

DTC P0133: Heated Oxygen Sensor Circuit Slow Response (bank 1, sensor 1)

BLA

BLUE

BLA

TO PCM

FROM MFI RELAY

PINK

AK400900

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

B-09

MU802605

B-22

Right Bank Heated Oxygen Sensor (front) Circuit

B-21

100

93 94 95

96 97 98

101 102 103 104

105 106 107 108

109 110 111 112 113

53 54 55 56

58 59 60 61 62

64 65 66 67 68 69

71 72 73 74 75

77 78 79 80 81 82

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-226

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) 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

AK303047

B-09 (B)

CONNECTOR: B-09

THROTTLE BODY

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK303013

CONNECTORS: B-21, B-22

PCM

AIR CLEANER

B-22 (B)

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-227

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 is open.

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

cent.

• More than 3 seconds have elapsed after the

abovementioned conditions have been met.

• The PCM monitors for this condition for 5 cycles

of 12 seconds each during the drive cycle.

Judgment Criteria

• The right 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-
ond.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 4

− Heated Oxygen Sensor Monitor

P.13B-6

F0: THRESHOLD VALUE FOR AVERAGE SWITDHING FREQUENCY

START

MONITORING

CONDITIONS

MALFUNCTION

GOOD

END

YES

Ff < F0

CALCULATE AVERAGE SWITCHING

FREQUENCY (Ff) OVER SPECIFIED TIMES

AK302395

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