Mitsubishi Galant 9G. Manual — part 699

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-238

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal

No. 4) to the cylinder 1, 4 heated oxygen sensor
(front) heater.

• The PCM (terminal No. 126) controls continuity to

the cylinder 1, 4 heated oxygen sensor (front)
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 1, 4 heated oxygen sensor heater (front)

current 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

.

AK303059

CONNECTOR: B-23

PCM

AB

AIR CLEANER

B-23

AK303820AB

CONNECTOR: B-37

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (FRONT)

B-37 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-239

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 1, 4 heated oxygen sensor

(front) heater is on.

• Battery positive voltage is between 11 and 16.5

volts.

Judgment Criteria

• The cylinder 1, 4 heated oxygen sensor (front)

heater current has continued to be lower than
0.16 ampere or higher than 7.5 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 1, 4 heated oxygen sen-

sor (front) heater circuit, harness damage or con-
nector damage.

• Open circuit in cylinder 1, 4 heated oxygen sen-

sor (front) heater.

• PCM failed.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT

< 0.16A

CURRENT

> 7.5A

AK302023

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-240

DIAGNOSIS

Required Special Tools:

• MB991316: Test Harness

• MB991923: Power Plant ECU Check Harness

STEP 1. Check harness connector B-37 at the cylinder 1, 4
heated oxygen sensor (front) 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.

AK303821

1

2

3

4

AB

CONNECTOR: B-37

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (FRONT)

B-37 (GR)

HARNESS
CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-241

STEP 2. Check the cylinder 1, 4 heated oxygen sensor
(front).
(1) Disconnect cylinder 1, 4 heated oxygen sensor (front)

connector B-37 and connect test harness special tool,
MB991316, to the connector on the cylinder 1, 4 heated
oxygen (front) sensor side.

(2) Measure the resistance between heated oxygen sensor

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

Standard value: 4.5

− 8.0 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 4.5 and 8.0 ohms

[at 20

°C (68°F)]?

YES : Go to Step 3.
NO : Replace the cylinder 1, 4 heated oxygen sensor

(front). Then go to Step 12.

AK303821

1

2

3

4

AB

CONNECTOR: B-37

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (FRONT)

B-37 (GR)

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01624 AT

MB991316

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

BLUE

RED