Mitsubishi Lancer Evolution X. Manual - part 291

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-229

STEP 10. Measure the sensor offset voltage at ECM 
connector B-09 by using power plant ECU check harness 
special tool MB992110.
(1) Disconnect all ECM connectors. Connect the power plant 

ECU check harness special tool MB992110 between the 
separated connectors.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 39 and ground.

• Voltage should be between 0.4 and 0.6 volt.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 0.4 and 0.6 volt?

YES : Go to Step 11.
NO :  Check harness connector A-13 at intermediate 

connector for damage, and repair or replace as 
required. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. If intermediate connector is in 

good condition, repair harness wire between headed 
oxygen sensor (front) connector C-34 (terminal No. 4) 
and ECM connector B-09 (terminal No. 39) because 
of open circuit or harness damage. Then go to Step 
14.

STEP 11. Check for harness damage between heated 
oxygen sensor (front) connector C-34 (terminal No. 4) and 
ECM connector B-09 (terminal No. 39).
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 14.
Q: Is the harness wire in good condition?

YES : Go to Step 12.
NO :  Repair it. Then go to Step 14.

AK604040

ECM

AB

Body side harness 

MB992110

AK604185

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AB

Power plant ECU
check harness connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-230

STEP 12. Check for short circuit to ground and harness 
damage between heated oxygen sensor (front) connector 
C-34 (terminal No. 3) and ECM connector B-09 (terminal 
No. 38).
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 14.
Q: Is the harness wire in good condition?

YES : Go to Step 13.
NO :  Repair it. Then go to Step 14.

STEP 13. Check the heated oxygen sensor (front).
(1) Disconnect the 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) Warm up the engine until engine coolant temperature 

reaches 80° C (176° F) or higher.

(3) Rev the engine for 5 minutes or more with the engine speed 

of 2,000 r/min.

(4) Connect a digital voltage meter between terminal No. 3 and 

terminal No. 4.

(5) While repeatedly revving the engine, measure the heated 

oxygen sensor (front) output voltage.

Standard value: 0.6 − 1.0 V

CAUTION

• Be very careful when connecting the jumper wires; 

incorrect connection can damage the heated oxygen 
sensor.

• Be careful the heater can be damaged if a voltage 

beyond 8 volts is applied to the heated oxygen sensor 
heater.
NOTE: If the temperature of sensing area does not reach 
the high temperature [of approximately 400

°

C (752

°

F) or 

more] even though the heated oxygen sensor is normal, the 
output voltage would be possibly low in spite of the rich 
air/fuel ratio. Therefore, if the output voltage is low, use a 
jumper wire to connect the terminal No. 1 and the terminal 
No. 2 of the heated oxygen sensor with the positive terminal 
and the negative terminal of 8 volts power supply respec-
tively, then check again.

Q: Is the measured voltage between 0.6 and 1.0 volt?

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 14.

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

Step 14.

AK604493AB

MB991658

Heated oxygen
sensor component
side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 14. 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 22 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0131 set?

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

DTC P0132: Heated Oxygen Sensor (front) Circuit High Voltage

AK704249

1

2

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3 4

1

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4

3

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22

1

10

0.5 V

AB

1

4

2

3

39

SKY BLUE

SKY BLUE

38

HEATED OXYGEN SENSOR (FRONT) CIRCUIT

B-09

C-34

6

RED

RED

7

A-13

HEATED OXYGEN SENSOR
(FRONT)

FROM MFI RELAY

TO ECM

ENGINE
CONTROL
MODULE

AK704229AB

Connector: A-13

A-13

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the ECM (ter-
minal No. 38) from the output terminal (terminal 
No. 3) of the heated oxygen sensor (front).

• Terminal No. 4 of the heated oxygen sensor 

(front) is grounded with ECM (terminal No. 39).

• The ECM applies an offset voltage of 0.5 volt to 

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

.

TECHNICAL DESCRIPTION

• The heated oxygen sensor (front) detects the 

concentration of oxygen in the exhaust gas; it 
converts those data to voltage, and inputs the 
resulting signals to the ECM.

• When the heated oxygen sensor (front) begins to 

deteriorate, the heated oxygen sensor signal 
response becomes poor.

• The ECM checks for the heated oxygen sensor 

(front) output voltage.

.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor (front) output voltage is over 

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)

• Heated oxygen sensor (front) heater monitor
• Misfire monitor
• Fuel system monitor
• Heated oxygen sensor (rear) feedback control 

system monitor

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
• Throttle position sensor
• Accelerator pedal position sensor

.

AK704228

AB

Heated oxygen
sensor (front)

Connector: C-34

C-34 (B)

SRS-ECU