Mitsubishi Evolution X. Manual — part 273

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-69

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

• Open or shorted heated oxygen sensor (front)

heater circuit, harness damage or connector
damage.

• Heated oxygen sensor (front) heater failed.

• ECM failed.

DIAGNOSIS

Required Special Tools:

• MB991658: Test Harness

• MB992110: Power Plant ECU Check Harness

STEP 1. 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 2.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 12.

STEP 2. 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

° C (68° F)]?

YES : Go to Step 3.
NO : Replace the heated oxygen sensor (front). Then go to

Step 12.

STEP 3. Measure the power supply voltage at heated
oxygen sensor (front) harness side connector C-34.
(1) Disconnect the connector C-34 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)

present?
YES : Go to Step 5.
NO : Go to Step 4.

AK604492AB

MB991658

Heated oxygen
sensor component
side connector

AK604172

2 1
4 3

C-34 harness
connector:
component side

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 4. Check harness connector A-34X at the MFI relay
for damage.
Q: Is the harness connector in good condition?

YES : Repair harness wire between MFI relay connector

A-34X (terminal No. 2) and heated oxygen sensor
(front) connector C-34 (terminal No. 1) because of
open circuit or short circuit to ground. Then go to Step
12.

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

Connector Inspection

P.00E-2

. Then go to Step 12.

STEP 5. Measure the power supply 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. 34 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)

present?
YES : Go to Step 8.
NO : Go to Step 6.

AK604040

ECM

Body side harness

MB992110

AK604173

16 15 14 13 12 11 10 9 8 7 6 5 4 3

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

Power plant ECU
check harness connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 6. Check harness connector B-09 at ECM 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.

STEP 7. Check for open circuit and short circuit to ground
between heated oxygen sensor (front) connector C-34
(terminal No. 2) and ECM connector B-09 (terminal No. 34).
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 : Replace the ECM. When the ECM is replaced,

P.42B-12

or GROUP 42C, ID Codes

Registration Judgment Table <Vehicles with WCM>

P.42C-9

. Then go to Step 12.

NO : Repair it. 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 MFI relay
connector A-34X (terminal No. 2) and heated oxygen
sensor (front) connector C-34 (terminal No. 1).
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 heated
oxygen sensor (front) connector C-34 (terminal No. 2) and
ECM connector B-09 (terminal No. 34).
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 11.
NO : Repair it. Then go to Step 12.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 11. 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 P0031 set?