Mitsubishi Evolution X. Manual - part 272

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-65

STEP 2. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Pattern 20 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0017 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 4.

NO :  It can be assumed that this malfunction is intermittent. 

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

− How to Cope with 

Intermittent Malfunctions 

P.00-15

.

STEP 3. Check timing mark on the timing chain.
Q: Is timing chain in out of place?

YES : Repair it. Then go to Step 4.
NO :  Check the following items, and repair or replace the 

defective items. 

a. Check the timing chain loose.
b. Check the exhaust variable valve timing 

sprocket tooth coming off.

Then go to Step 4.

STEP 4. 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 − Pattern 20 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0017 set?

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-66

DTC P0031: Heated Oxygen Sensor (front) Heater Circuit Low

AK704225

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HEATED OXYGEN SENSOR (FRONT) HEATER CIRCUIT

20A

WHITE

BLUE-BLA

CK

WHITE

WHITE

A-34X

MFI
RELAY

RELAY BOX
(ENGINE COMPARTMENT)

4

3

1

2

22

TO ECM

HEATED OXYGEN SENSOR
(FRONT)

1

4

2

3

TO ECM

TO ECM

ENGINE
CONTROL
MODULE

34

C-34

B-09

A-13

36

FUSIBLE LINK

BLUE

8

OFF

ON

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-67

.

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

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MULTIPORT FUEL INJECTION (MFI)

13A-68

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.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Pattern 2 

P.13A-9

.

.

End

No

No

Malfunction

Good

Current < 0.17A

or

Current > 10.5A

Voltage < 2.0V

AK604306

Heater ON

No

No

Start

Yes

Yes

Yes

Yes

Yes

No

Continuous
failure for 2secs

Monitoring
conditions