Mitsubishi Galant (2004+). Manual - part 1156

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-317

STEP 14. Check the left bank heated oxygen sensor (front).

(1) Disconnect the left bank heated oxygen sensor (front)

connector B-25 and connect test harness special tool,
MD998464, to the connector on the left 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 left bank heated oxygen sensor (front).

Then go to Step 15.

AK303071

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MD998464

WHITE

BLACK

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-318

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 P0150 set?

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

DTC P0151: Heated Oxygen Sensor Circuit Low Voltage (bank 2, sensor 1)

BLA

TO PCM

FROM MFI RELAY

WHITE

AK302844

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

POWERTRAIN CONTROL
MODULE (PCM)

B-25

MU802605

B-22

Left Bank Heated Oxygen Sensor (front) Circuit

B-21

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

100

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-319

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 input the resulting signal to the PCM.

• When the left 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 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) 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

AK303070

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-25

B-25 (B)

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-320

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• 3 minutes or more have passed since the engine

starting sequence was completed.

• Left bank 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.

• Mass airflow sensor output is 8 g/sec or more.

START

> =4.5V

2secs HAS PASSED

YES

MALFUNCTION

MONITORING

CONDITIONS

YES

MONITORING

CONDITIONS

+5V ON

AK302397

< 0.2V

10secs HAS PASSED

YES

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

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