Mitsubishi Lancer Evolution X. Manual - part 256

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-89

STEP 6. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 7.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 7. Check for open circuit and short circuit to ground 
between heated oxygen sensor (front) connector C-34 
(terminal No. 2) and ECM connector B-09 (terminal No. 34).
NOTE: Check harness after checking intermediate connector 
A-13. If intermediate connector is damaged, repair or replace it. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

Then go to Step 12.
Q: Is the harness wire in good condition?

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-11

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 12.

NO :  Repair it. Then go to Step 12.

STEP 8. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 9.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 9. Check for harness damage between MFI relay 
connector A-34X (terminal No. 2) and heated oxygen 
sensor (front) connector C-34 (terminal No. 1).
Q: Is the harness wire in good condition?

YES : Go to Step 10.
NO :  Repair it. Then go to Step 12.

STEP 10. Check for harness damage between heated 
oxygen sensor (front) connector C-34 (terminal No. 2) and 
ECM connector B-09 (terminal No. 34).
NOTE: Check harness after checking intermediate connector 
A-13. If intermediate connector is damaged, repair or replace it. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

Then go to Step 12.
Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO :  Repair it. Then go to Step 12.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-90

STEP 11. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function − OBD-II Drive Cycle − Pattern 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0031 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-11

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 12.

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 12. 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 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0031 set?

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-91

DTC P0032: Heated Oxygen Sensor (front) Heater Circuit High

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-92

.

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.

.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor heater (front) current 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