Mitsubishi Lancer Evolution X. Manual - part 298

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-257

DIAGNOSIS

STEP 1. Check harness connector D-35 at heated oxygen 
sensor (rear) and harness connector B-09 at ECM 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 3.

STEP 2. Check for short circuit to power supply between 
heated oxygen sensor (rear) connector D-35 (terminal No. 
3) and ECM connector B-09 (terminal No. 40).
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 3.

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 3.

NO :  Repair it. Then go to Step 3.

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 23 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0138 set?

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-258

DTC P0139: Heated Oxygen Sensor (rear) Circuit Slow Responce

AK704250

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

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 5 6

AB

D-35

FROM MFI RELAY

TO ECM

1

4

2

3

HEATED OXYGEN SENSOR (REAR) CIRCUIT

HEATED OXYGEN
SENSOR (REAR)

B-09

YELLO

W

ORANGE

ORANGE

YELLO

W

ENGINE
CONTROL
MODULE

0.5 V

C-45

3

41

40

2

ORANGE

YELLO

W

6

5

A-13

AK704229AB

Connector: A-13

A-13

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

AK704251

Connector: C-45

C-45

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-259

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the ECM (ter-
minal No. 40) from the output terminal (terminal 
No. 3) of the heated oxygen sensor (rear).

• Terminal No. 4 of the heated oxygen sensor 

(rear) is grounded with ECM (terminal No. 41).

• The ECM applies an offset voltage of 0.5 volt to 

terminal No. 4 of the heated oxygen sensor 
(rear).

.

TECHNICAL DESCRIPTION

• The output signal of the heated oxygen sensor 

(front) is compensated by the output signal of the 
heated oxygen sensor (rear).

• The ECM checks for the heated oxygen sensor 

(rear) output voltage.

.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor (rear) output voltage does not 

reach 0.2 volt after fuel cut operation.

.

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)

• Heated oxygen sensor (front) monitor
• Heated oxygen sensor (front) heater monitor
• Heated oxygen sensor (rear) heater monitor
• Heated oxygen sensor (front) inactive monitor
• Heated oxygen sensor offset voltage monitor
• Air/fuel ratio feedback monitor

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor

.

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-260

DTC SET CONDITIONS
Logic Flow Chart

.

No

No

No

No

No

No

Good

Malfunction

N = 0

N = N + 1

End

Fuel cut starts?

Fuel cut continues?

Output voltage >= 0.5V 

at fuel cut start?

Output voltage
reaches 0.2V?

No

Start

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Monitoring conditions

Trl >= T0

Tslope > T1

N = 3

Trl       : Time from fuel cut start
Tslope: Time from 0.4 V to 0.2 V
T0, T1: Threshold value

AK900362