Mitsubishi Lancer Evolution X. Manual - part 255

 

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Mitsubishi Lancer Evolution X. Manual - part 255

 

 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-85

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

No. 2) to the heated oxygen sensor (front) heater.

• The ECM (terminal No. 34) controls continuity to 

the heated oxygen sensor (front) heater by turn-
ing the power transistor in the ECM "ON" and 
"OFF".

.

TECHNICAL DESCRIPTION

• The ECM checks whether the heater current is 

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

• The ECM checks whether the heater voltage is 

within a specified range when the heater is not 
energized.

.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor heater (front) current or volt-

age is out of specified range.

.

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)

• Not applicable

.

AK704229AB

Connector: A-13

A-13

AK704226

Connector: A-34X

MFI relay

A-34X

AB

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

AK704228

AB

Heated oxygen
sensor (front)

Connector: C-34

C-34 (B)

SRS-ECU

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-86

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• More than 2 seconds have passed since the 

engine starting sequence was completed.

• While the heated oxygen sensor (front) heater is 

on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgement Criterion

• The heated oxygen sensor (front) heater current 

has continued to be lower than 0.17 ampere for 2 
seconds.

Check Conditions

• More than 2 seconds have passed since the 

engine starting sequence was completed.

• While the heated oxygen sensor (front) heater is 

off.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgement Criterion

• The heated oxygen sensor (front) heater voltage 

has continued to be lower than 2.0 volts for 2 sec-
onds.

.

End

No

No

Malfunction

Good

Current < 0.17A

or

Current > 10.5A

Voltage < 2.0V

AK900352

Heater activation 
command ON

No

No

Start

Yes

Yes

Yes

Yes

Yes

No

Continuous
failure for 2secs

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-87

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 2 

P.13A-9

.

.

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

• Open or shorted heated oxygen sensor (front) 

heater circuit, harness damage or connector 
damage.

• Heated oxygen sensor (front) heater failed.
• ECM failed. 

DIAGNOSIS

Required Special Tools:

• MB991658: Test Harness
• MB992110: Power Plant ECU Check Harness

STEP 1. Check harness connector C-34 at the 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.

STEP 2. Check the heated oxygen sensor (front).
(1) Disconnect heated oxygen sensor (front) connector C-34 

and connect test harness special tool, MB991658, to the 
connector on the heated oxygen sensor (front) side.

(2) Measure the resistance between heated oxygen sensor 

connector terminal No. 1 and terminal No. 2.

Standard value: 4.5  8.0 Ω [at 20° C (68° F)]

Q: Is the measured resistance between 4.5 and 8.0 Ω [at 

20° C (68° F)]?
YES : 
Go to Step 3.
NO :  Replace the heated oxygen sensor (front). Then go to 

Step 12.

STEP 3. Measure the power supply voltage at heated 
oxygen sensor (front) harness side connector C-34.
(1) Disconnect the connector C-34 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : 
Go to Step 5.
NO :  Go to Step 4.

AK604492AB

MB991658

Heated oxygen
sensor component
side connector

AK604172

2 1
4 3

C-34 harness
connector:
component side 

AH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-88

STEP 4. Check harness connector A-34X at the MFI relay 
for damage.
Q: Is the harness connector in good condition?

YES : Repair harness wire between MFI relay connector 

A-34X (terminal No. 2) and heated oxygen sensor 
(front) connector C-34 (terminal No. 1) because of 
open circuit or short circuit to ground. Then go to Step 
12.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 5. Measure the power supply voltage at ECM 
connector B-09 by using power plant ECU check harness 
special tool MB992110.
(1) Disconnect all ECM connectors. Connect the power plant 

ECU check harness special tool MB992110 between the 
separated connectors.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 34 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : 
Go to Step 8.
NO :  Go to Step 6.

AK604040

ECM

AB

Body side harness 

MB992110

AK604173

16 15 14 13 12 11 10 9 8 7 6 5 4 3

2

1

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33

64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49

AB

Power plant ECU
check harness connector

 

 

 

 

 

 

 

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