Mitsubishi Lancer Evolution X. Manual - part 294

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-241

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• More than 300 seconds have passed since the 

engine starting sequence was completed.

• Engine coolant temperature is higher than 7° C 

(45° F).

• Engine speed is higher than 1,188 r/min.
• Volumetric efficiency is higher than 30 percent.
• Throttle position sensor output voltage is lower 

than 3.3 volts.

• Except while fuel is being shut off.
• Monitoring time: 30 seconds.

Judgement Criterion

• Heated oxygen sensor (front) output voltage does 

not get across lean/rich criteria (about 0.5 volt) 
within about 30 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 11 

P.13A-9

.

.

TROUBLESHOOTING HINTS (The most 
likely causes for this code to be set are: )

• Heated oxygen sensor (front) deteriorated.
• Harness damage in heated oxygen sensor (front) 

output line.

• Heated oxygen sensor (rear) deteriorated.

NOTE: When the heated oxygen sensor (front) 
begins to deteriorate, the heated oxygen sensor 
output voltage will deviate from the voltage when 
the sensor was new (normally 0.5 volt at stoichio-
metric ratio). This deviation will be corrected by 
the heated oxygen sensor (rear).

End

No

No

No

Malfunction

Good

30secs have passed?

AK704112

Start

Yes

Yes

Yes

Monitoring
conditions

Heated oxygen sensor

(front) output voltage

crosses lean/rich criteria?

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-242

If the heated oxygen sensor (rear) responds 
poorly because it has deteriorated, it will improp-
erly correct the heated oxygen sensor (front). 
Thus, even when closed loop control is being 
effected, the fluctuation of the heated oxygen 
sensor (front) output voltage decreases, without 
intersecting with 0.5 volt. As a result, there is a 
possibility of DTC P0134 becoming registered.

• Open circuit in injector.
• Harness damage in injector circuit.
• Connector damage.
• ECM failed. 
• Exhaust leak.
• Air drawn in from gaps in gasket, seals, etc.
• Incorrect fuel pressure.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

• MB991658: Test Harness

STEP 1. Using scan tool MB991958, check data list item 
AD: Heated Oxygen Sensor (rear).

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991958 to the data reading mode for item 

AD, Heated Oxygen Sensor (rear).

a. Transaxle: 2nd speed
b. Drive with wide open throttle

c. Engine: 3,500 r/min

• The output voltage should be between 0.6 and 1.0 

volt.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 2.
NO :  Refer to DTC P0137 − Heated Oxygen Sensor (rear) 

Circuit Low Voltage 

P.13A-246

, DTC P0138 − Heated 

Oxygen Sensor (rear) Circuit High Voltage 

P.13A-254

, DTC P0139 − Heated Oxygen Sensor 

(rear) Circuit Slow Response 

P.13A-258

, P0140 − 

Heated Oxygen Sensor (rear) Circuit No Activity 
Detected 

P.13A-263

.

STEP 2. Check for exhaust leak.
Q: Are there any abnormalities?

YES : Repair it. Then go to Step 12.
NO :  Go to Step 3.

STEP 3. Check for intake system vacuum leak.
Q: Are there any abnormalities?

YES : Repair it. Then go to Step 12.
NO :  Go to Step 4.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-243

STEP 4. Check harness connector C-34 at the heated 
oxygen sensor (front) for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 5.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 5. 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 : Go to Step 6.
NO :  Replace the heated oxygen sensor (front). Then go to 

Step 12.

STEP 6. Check harness connector B-101, B-102, B-103, 
and B-104 at injector 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.

AK604493AB

MB991658

Heated oxygen
sensor component
side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-244

STEP 7. Check the injectors.
(1) Disconnect each injector connector.
(2) Measure the resistance between injector side connector 

terminal No. 1 and No. 2.

Standard value: 10.5 − 13.5 Ω [at 20° C (68° F)]

Q: Is the measured resistance between 10.5 and 13.5 Ω [at 

20° C (68° F)]?
YES : Go to Step 8.
NO :  Replace the injector. 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 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 12.
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 injector 
connector and ECM connector.

a. Check the harness wire between injector connector B-101 

(terminal No. 2) and ECM connector B-09 (terminal No. 2) 
when checking No. 1 cylinder.

b. Check the harness wire between injector connector B-102 

(terminal No. 2) and ECM connector B-09 (terminal No. 3) 
when checking No. 2 cylinder.

c. Check the harness wire between injector connector B-103 

(terminal No. 2) and ECM connector B-09 (terminal No. 18) 
when checking No. 3 cylinder.

d. Check the harness wire between injector connector B-104 

(terminal No. 2) and ECM connector B-09 (terminal No. 19) 
when checking No. 4 cylinder.

Q: Is the harness wire in good condition?

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

AK604038

1 2

AB

Injector side
connector