Mitsubishi Evolution X. Manual - part 305

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-197

STEP 2. Measure the sensor output voltage at engine 
coolant temperature sensor connector B-08 by 
backprobing.
(1) Do not disconnect the connector B-08.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 and ground by 

backprobing.

• When engine coolant temperature is −20° C (−4° F), volt-

age should be between 3.9 and 4.5 volts.

• When engine coolant temperature is 0° C (32° F), volt-

age should be between 3.2 and 3.8 volts.

• When engine coolant temperature is 20° C (68° F), volt-

age should be between 2.3 and 2.9 volts.

• When engine coolant temperature is 40° C (104° F), volt-

age should be between 1.3 and 1.9 volts.

• When engine coolant temperature is 60° C (140° F), volt-

age should be between 0.7 and 1.3 volts.

• When engine coolant temperature is 80° C (176° F), volt-

age should be between 0.3 and 0.9 volt.

(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 5.

STEP 3. Check harness connector B-08 at the engine 
coolant temperature sensor 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. Using scan tool MB991958, check data list item 6: 
Engine Coolant Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 

6, Engine Coolant Temperature Sensor.

• The engine coolant temperature and temperature 

shown with the scan tool should approximately match.

(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-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 14.

AK201572

2

1

AH

B-08 harness 
connector: 
harness side

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 5. Check harness connector B-08 at engine coolant 
temperature sensor 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.

STEP 6. Measure the sensor supply voltage at engine 
coolant temperature sensor harness side connector B-08.
(1) Disconnect the connector B-08 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 between 4.5 and 4.9 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 8.
NO :  Go to Step 7.

STEP 7. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector 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-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. 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 the continuity at engine coolant 
temperature sensor harness side connector B-08.
(1) Disconnect the connector B-08 and measure at the harness 

side.

(2) Check for the continuity between terminal No. 2 and 

ground.

• Continuity (2 ohms or less)

Q: Does continuity exist?

YES : Go to Step 11.
NO :  Go to Step 9.

AK604181

1

2

AD

B-08 harness
connector:
component side 

AK604180

1

2

B-08 harness
connector:
component side 

AD

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-199

STEP 9. Check harness connector B-09 at 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.

STEP 10. Check for harness damage between engine 
coolant temperature sensor connector B-08 (terminal No. 
2) and ECM connector B-09 (terminal No. 27).
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-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 14.

NO :  Repair it. Then go to Step 14.

STEP 11. Check the engine coolant temperature sensor.
Refer to Engine Coolant Temperature Sensor Check 

P.13A-907

.

Q: Is the engine coolant temperature sensor normal?

YES : Go to Step 12.
NO :  Replace the engine coolant temperature sensor. Then 

go to Step 14.

STEP 12. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 13.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 14.

STEP 13. Check for harness damage between engine 
coolant temperature sensor connector B-08 (terminal No. 
1) and ECM connector B-09 (terminal No. 26).
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-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 14.

NO :  Repair it. Then go to Step 14.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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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 8 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0125 set?

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

DTC P0128: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

.

TECHNICAL DESCRIPTION

• The ECM checks the time for the cooling water 

temperature to reach the judgement temperature.

.

DESCRIPTIONS OF MONITOR METHODS

Engine coolant temperature does not reach 77

° C 

(171

° F) within specified period after cold start.

.

MONITOR EXECUTION

Once per driving cycle

.

MONITOR EXECUTION CONDITIONS 
(Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

.