Mitsubishi Montero (2004+). Manual - part 353

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-899

STEP 9. Using scan tool MB991958, check data list item 39: 
Heated oxygen sensor bank 1, sensor 1 (right front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item 

39, Heated Oxygen Sensor bank 1, sensor 1 (right front).

• Voltage should fluctuate between 0 − 0.4 volts and 0.6 − 

1.0 volts while after the engine has been warmed.

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

YES : Go to Step 10.
NO :  Go to Step 12.

STEP 10. Check the EGR system.
Refer to GROUP 17, Emission Control System 

− General 

Description (EGR System) 

P.17-68

.

Q: Is the EGR system normal?

YES : Go to Step 11.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

STEP 11. Using scan tool MB991958, check data list item 
69: Heated oxygen sensor bank 1, sensor 2 (right 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 

69, Heated Oxygen Sensor bank 1, sensor 2 (right rear).

• Average voltage should be 0.6 volts or less, when idling.

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

YES : Go to Step 16.
NO :  Replace the right bank heated oxygen sensor (front). 

Then confirm that the malfunction symptom is 
eliminated.

AK302970

AB

MB991911

MB991824

MB991827

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-900

STEP 12. Using scan tool MB991958, check data list item 
11: Heated oxygen sensor bank 2, sensor 1 (left front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item 

11, Heated Oxygen Sensor bank 2, sensor 1 (left front).

• Warm up the engine. When the engine is decelerated 

suddenly from 4,000 r/min, the output voltage should 
increase from 200 millivolts or less to 600 

− 1,000 milli-

volts in a few seconds.

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

YES : Go to Step 13.
NO :  Go to Step 15.

STEP 13. Check the EGR system.
Refer to GROUP 17, Emission Control System 

− General 

Description (EGR System) 

P.17-68

.

Q: Is the EGR system normal?

YES : Go to Step 14.
NO :  Repair or replace. Then confirm that the malfunction 

symptom is eliminated.

STEP 14. Using scan tool MB991958, check data list item 
59: Heated oxygen sensor bank 2, sensor 2 (left 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 

59, Heated Oxygen Sensor bank 2, sensor 2 (left rear).

• Average voltage should be 0.6 volts or less, when idling.

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

YES : Go to Step 16.
NO :  Replace the left bank heated oxygen sensor (front). 

Then confirm that the malfunction symptom is 
eliminated.

AK302970

AB

MB991911

MB991824

MB991827

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-901

STEP 15. Check the fuel pressure.
Refer to On-vehicle Service 

− Fuel Pressure Test 

P.13A-995

.

Q: Is the fuel pressure normal?

YES : Go to Step 16.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

STEP 16. Check the following items.
(1) Check the following items, and repair or replace the 

defective items.

a. Check the injectors for fuel leakage.
b. Check the ignition coil, spark plugs, spark plug cables.

c. Check compression pressure.

d. Check the positive crankcase ventilation system.
e. Check the evaporative emission system.

(2) Then check the malfunction symptom.
Q: Is the malfunction symptom eliminated?

YES : The check is completed.
NO :  Replace the catalytic converter. Then confirm that the 

malfunction symptom is eliminated.

INSPECTION PROCEDURE 24: Purge Flow Test of the Evaporative Emission Canister Failure.

.

COMMENT

• The test fails when the purge line or purge port is 

clogged or if the evaporative emission purge 
solenoid fails.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this case: )

• Purge line or purge port is clogged.

• Malfunction of the evaporative emission purge 

solenoid.

• Evaporative emission canister is clogged.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-902

STEP 1. Using scan tool MB991958, read the diagnostic 
trouble code (DTC).

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) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Refer to Diagnostic Trouble Code Chart 

P.13A-26

.

NO :  Refer to GROUP 17, Emission Control System 

− 

Purge Control System Check (Purge Flow Check) 

P.17-66

.

INSPECTION PROCEDURE 25: Pressure Test of the Evaporative System Failure

.

COMMENT

• The test fails if there is a leak from the fuel tank or 

vapor line.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this case: )

• Loose fuel tank filler tube cap.

• Broken seal in fuel tank, vapor line evaporative 

emission canister.

DIAGNOSIS

STEP 1. Check the evaporative emission purge solenoid.
Refer to GROUP 17, Emission Control System 

− Evaporative 

Emission Purge Solenoid Check 

P.17-67

.

Q: Is the evaporative emission purge solenoid normal?

YES : Go to Step 2.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

AK302970

AB

MB991911

MB991824

MB991827