Mitsubishi Lancer Evolution X. Manual - part 290

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-225

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• Heated oxygen sensor offset voltage is between 

0.4 and 0.6 volt.

• Battery positive voltage is between 11 and 16.5 

volts.

• More than 330 seconds have passed since the 

engine starting sequence was completed.

Judgement Criterion

• Heated oxygen sensor (front) output voltage is 

lower than 0.2 volt for 2 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

 Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 22 

P.13A-9

.

.

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

• Heated oxygen sensor (front) failed.
• Open or shorted circuit in heated oxygen sensor 

(front) output line, or harness damage.

• Open circuit in heated oxygen sensor (front) 

ground line, or harness damage.

• Connector damage.
• ECM failed. 

End

Malfunction

No

No

No

2secs have passed?

Output voltage

< 0.2V

Good

AK604321

Start

Yes

Yes

Yes

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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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
• MB992110: Power Plant ECU Check Harness

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

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 

AC, Heated Oxygen Sensor (front).

• Warm up the engine. When the engine is revved, the 

output voltage should measure 0.6 to 1.0 volt.

• Warm up the engine. When the engine is idling, the out-

put voltage should repeat 0.4 volt or less and 0.6 to 1.0 
volt alternately.

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

YES : 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

.

NO :  Go to Step 2.

STEP 2. Measure the sensor output voltage at heated 
oxygen sensor (front) connector C-34 by backprobing
(1) Do not disconnect the connector C-34.
(2) Start the engine and run at idle.
(3) Measure the voltage between terminal No. 3 and ground by 

backprobing.

• Warm up the engine. When the engine is 2,500 r/min, 

the output voltage should repeat 0.4 volt or less and 0.6 
to 1.0 volt alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?

YES : Go to Step 3.
NO :  Go to Step 8.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

AK604183

1 2
3 4

AH

C-34 harness
connector:
harness side 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 3. Check harness connector B-09 at the ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 14.

STEP 4. Measure the sensor output 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) Start the engine and run at idle.

(3) Measure the voltage between terminal No. 38 and ground.

• Warm up the engine. When the engine is 2,500 r/min, 

the output voltage should repeat 0.4 volt or less and 0.6 
to 1.0 volt alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?

YES : Go to Step 5.
NO :  Go to Step 7.

STEP 5. Check harness connector C-34 at heated oxygen 
sensor (front) for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 6.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 14.

AK604040

ECM

AB

Body side harness 

MB992110

AK604184

16 15 14 13 12 11 10 9 8 7 6 5 4 3

2

1

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

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

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

AB

Power plant ECU
check harness connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 6. Using scan tool MB991958, check data list item 
AC: Heated Oxygen Sensor (front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item 

AC, Heated Oxygen Sensor (front).

• Warming up the engine. When the engine is revved, the 

output voltage should be 0.6 to 1.0 volt.

• Warming up the engine. When the engine is idling, the 

output voltage should repeat 0.4 volt or less and 0.6 to 
1.0 volt alternately.

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

YES : 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

.

NO :  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.

STEP 7. Check harness connector C-34 at heated oxygen 
sensor (front) for damage.
Q: Is the harness connector in good condition?

YES : 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 heated 
oxygen sensor (front) connector C-34 (terminal No. 3) 
and ECM connector B-09 (terminal No. 38) because 
of open circuit or harness damage. Then go to Step 
14.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 14.

STEP 8. Check harness connector C-34 at heated oxygen 
sensor (front) 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 14.

STEP 9. Check harness connector B-09 at the ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 10.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 14.