Mitsubishi Galant 9G. Manual — part 738

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-394

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal

No. 4) to the cylinder 2, 3 heated oxygen sensor
(rear) heater.

• The PCM (terminal No. 137) controls continuity to

the cylinder 2, 3 heated oxygen sensor (rear)
heater by turning the power transistor in the PCM
"ON" and "OFF".

.

TECHNICAL DESCRIPTION

• The PCM checks whether the heater current is

within a specified range when the heater is ener-
gized.

.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 2, 3 heated oxygen sensor heater (rear) cur-

rent is out of specified range when engine coolant
temperature is over 20

°C (68°F).

.

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)

• Not applicable

Sensor (The sensor below is determined to be

normal)

• Engine coolant temperature sensor

.

AK303803AB

CONNECTOR: B-17X

MFI RELAY

B-17X

AK303834AB

CONNECTOR: B-35

B-35 (B)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (REAR)

AK303059

CONNECTOR: B-23

PCM

AB

AIR CLEANER

B-23

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-395

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• 60 seconds have elapsed from the start of the

previous monitoring.

• Engine coolant temperature is higher than 20°C

(68

°F).

• While the cylinder 2, 3 heated oxygen sensor

(rear) heater is on.

• Battery positive voltage is between 11 and 16.5

volts.

Judgment Criteria

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

heater current has continued to be lower than
0.16 ampere or higher than 5.0 ampere for 4 sec-
onds.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-6

.

.

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

• Open or shorted cylinder 2, 3 heated oxygen sen-

sor (rear) heater circuit, or harness damage.

• Open circuit in cylinder 2, 3 heated oxygen sen-

sor (rear) heater.

• Connector damage.

• Cylinder 2, 3 heated oxygen sensor (rear) failed.

• PCM failed.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 5.0A

AK302027

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-396

DIAGNOSIS

Required Special Tools:

• MD998464: Test Harness

• MB991923: Power Plant ECU Check Harness

STEP 1. Check harness connector B-35 at the cylinder 2, 3
heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 2.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 12.

AK303835

1

2

3

4

AB

CONNECTOR: B-35

B-35 (B)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (REAR)

HARNESS
CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-397

STEP 2. Check the cylinder 2, 3 heated oxygen sensor
(rear).
(1) Disconnect cylinder 2, 3 heated oxygen sensor (rear)

connector B-35 and connect test harness special tool,
MD998464, to the connector on the cylinder 2, 3 heated
oxygen (rear) sensor side.

(2) Measure the resistance between heated oxygen sensor

connector terminal No. 1 (red clip) and terminal No. 3 (blue
clip).

Standard value: 11

− 18 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 11 and 18 ohms [at

20

°C (68°F)]?

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

(rear). Then go to Step 12.

AK303835

1

2

3

4

AB

CONNECTOR: B-35

B-35 (B)

CYLINDER 2, 3
HEATED OXYGEN
SENSOR (REAR)

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MD998464

BLUE

RED

AU