Mitsubishi Lancer Evolution X. Manual - part 259

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-101

STEP 10. Check for harness damage between heated 
oxygen sensor (rear) connector D-35 (terminal No. 2) and 
ECM connector B-09 (terminal No. 35).
NOTE: Check harness after checking intermediate connectors 
A-13 and C-45. If intermediate connectors are damaged, repair 
or replace them. 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.

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 P0037 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 P0037 set?

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-102

DTC P0038: Heated Oxygen Sensor (rear) Heater Circuit High

AK704230

1

3

2

4

2

8

7

6

5

4

3

11

21

20

19

18

17

16

15

14

13

12

9

22

1

10

2

8

7

6

5

4

3

11

21

20

19

18

17

16

15

14

13

12

9

22

1

10

1 2

3 4

1

2

3 4 5 6 7 8 9 10 11 12 13 14 15 16

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

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

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

1

12 13 14 15 16 1718 19 20 2122 2324

2 3 4 5

6 7 8 9 10 11

1

2

3 4 5 6

WHITE

WHITE

HEATED OXYGEN SENSOR (REAR) HEATER CIRCUIT

36

FUSIBLE LINK

AB

D-35

4

1

20A

WHITE

A-34X

4

3

1

2

22

C-47

B-09

OFF

ON

C-43

1

4

2

3

RED-

GREEN

RED-

GREEN

11

10

2

C-45

A-13

35

J/C(4)

HEATED OXYGEN SENSOR
(REAR)

RELAY BOX
(ENGINE COMPARTMENT)

BR

O

WN

BR

O

WN

ENGINE
CONTROL
MODULE

TO ECM

TO ECM

TO ECM

MFI
RELAY

BR

O

WN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-103

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

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

• The ECM (terminal No. 35) controls continuity to 

the heated oxygen sensor (rear) 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 (rear) 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

AK704231

Connectors: C-43, C-45 and C-47

C-47

C-45

C-43 (B)

AB

AK704232

Heated oxygen
sensor (rear)

Connector: D-35

D-35 (B)

AB

Rear heater
duct

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-104

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 (rear) heater is 

on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgement Criterion

• The heated oxygen sensor (rear) heater current 

has continued to be higher than 10.5 ampere for 
2 seconds.

.

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:)

• Heated oxygen sensor (rear) failed.
• ECM failed.

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