Mitsubishi Lancer Evolution X. Manual - part 257

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-93

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 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 (front) heater 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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-94

DIAGNOSIS

Required Special Tool:

• MB991658: Test Harness

STEP 1. 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 2.
NO :  Replace the heated oxygen sensor (front). Then go to 

Step 3.

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 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0032 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 3.

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. 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 P0032 set?

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

AK604492AB

MB991658

Heated oxygen
sensor component
side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-95

DTC P0037: Heated Oxygen Sensor (rear) Heater Circuit Low

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

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MULTIPORT FUEL INJECTION (MFI)

13A-96

.

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.

• 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 (rear) heater 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

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