Mitsubishi Galant (2004+). Manual — part 878

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-329

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 60°C

(140

°F).

• Engine speed is between 1,200 and 3,000 r/min.

• Volumetric efficiency is between 25 and 60 per-

cent.

• Under the closed loop air/fuel control.

• The accelerator pedal is open.

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

percent.

• More than 2 seconds have elapsed after the

above mentioned conditions have been met.

• The PCM monitors for this condition for 7 cycles

of 10 seconds each during the drive cycle.

Judgment Criteria

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

sends "lean" and "rich" signals alternately 9 times
or less for 10 seconds. <Federal>

or

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

sends "lean" and "rich" signals alternately 11
times or less for 10 seconds. <California>

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.13A-5

.

.

F0: THRESHOLD VALUE FOR AVERAGE SWITCHING FREQUENCY

START

MONITORING

CONDITIONS

MALFUNCTION

GOOD

END

NO

NO

YES

YES

Ff < F0

CALCULATE AVERAGE SWITCHING

FREQUENCY (Ff) OVER SPECIFIED TIMES

AK302021

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-330

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

• Cylinder 2, 3 heated oxygen sensor (front) deteri-

orated.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

• MB991316: Test Harness

STEP 1. Using scan tool MB991958, check data list item 11:
Cylinder 2, 3 Heated Oxygen Sensor (front).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.

(3) Set scan tool MB991958 to the data reading mode for item

11, Cylinder 2, 3 Heated Oxygen Sensor (front).

(4) Warm up the engine, 2,500 r/min.

• Output voltage repeats 0.4 volt or less and 0.6 − 1.0 volt

10 times or more within 10 seconds.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

P.00-6

.

NO : Go to Step 2.

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-331

STEP 2. Check the cylinder 2, 3 heated oxygen sensor
(front).

(1) Disconnect the cylinder 2, 3 heated oxygen sensor (front)

connector B-36 and connect test harness special tool
MB991316 to the connector on the cylinder 2, 3 heated
oxygen sensor (front) side.

(2) Warm up the engine until engine coolant temperature

reaches 80

°C (176°F) or higher.

(3) Perform a racing 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 cylinder

2, 3 heated oxygen sensor (front) output voltage.

Standard value: 0.6

− 1.0 volt

CAUTION

• Be very careful when connecting the jumper wires;

incorrect connection can damage the heated oxygen
sensor (front).

• Be careful the heater is broken when voltage of beyond

8 volts is applied to the heated oxygen sensor (front)
heater.
NOTE: If the sufficiently high temperature [of approximate
400

°

C (752

°

F) or more] is not reached although the heated

oxygen sensor (front) is normal, the output voltage would be
possibly low although the rich air/fuel ratio. Therefore, if the
output voltage is low, use a jumper wire to connect the ter-
minal No. 1 (red clip) and the terminal No. 3 (blue clip) of
the heated oxygen sensor (front) with the positive terminal
and the negative terminal of 8 volts power supply respec-
tively, then check again.

Q: Is the measured voltage between 0.6 and 1.0 volt?

YES : Go to Step 3.
NO : Replace the cylinder 2, 3 heated oxygen sensor

(front). Then go to Step 4.

AK303830

1

2

3

4

AB

CONNECTOR: B-36

B-36 (GR)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (FRONT)

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MB991316

WHITE

BLACK

AN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-332

STEP 3. Check harness connector B-36 at cylinder 2, 3
heated oxygen sensor (front) and harness connector B-21,
B-22 at PCM for damage.

Q: Is the harness connector in good condition?

YES : Replace the PCM. Then go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 4.

AK303830

1

2

3

4

AB

CONNECTOR: B-36

B-36 (GR)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (FRONT)

HARNESS
CONNECTOR:
COMPONENT SIDE

AK303052

55

56

54 53 52 51

57

62 61 60 59 58

63

69 68 67 66 65 64

70

75 74 73 72 71

76

82 81 80 79 78 77

83

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

CONNECTORS: B-21, B-22

AB

B-21 HARNESS CONNECTOR:
COMPONENT SIDE

B-22 HARNESS CONNECTOR:
COMPONENT SIDE

PCM

AIR CLEANER

B-22 (B)

B-21 (B)