Mitsubishi Montero (2002-2004). Manual — part 644

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DIAGNOSTIC TROUBLE CODE PROCEDURES

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STEP 12. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 6

− Other Monitor

P.13Ab-2

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0161 set?

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

DTC P0171: System too Lean (bank 1)

.

Fuel Trim Circuit

• Refer to DTC P0201 − P0206, Injector Circuit.

P.13Ac-318

.

CIRCUIT OPERATION

• Refer to DTC P0201 − P0206, Injector Circuit.

P.13Ac-318

.

TECHNICAL DESCRIPTION

• If a malfunction occurs in the fuel system, the fuel

trim value becomes too large.

• The PCM checks whether the fuel trim value is

within a specified range.

.

DTC SET CONDITIONS

Check Conditions

• Engine coolant temperature is lower than approx-

imately 100

°C (212°F) when the engine is

started.

• Intake air temperature is lower than 60°C (140°F)

when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is 100 Hz

or more.

Judgment Criteria

• Long-term fuel trim has continued to be higher

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher

than +7.4 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is lower than approx-

imately 100

°C (212°F) when the engine is

started.

• Intake air temperature is lower than 60°C (140°F)

when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is 100 Hz

or less.

Judgment Criteria

• Long-term fuel trim has continued to be higher

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher

than +12.5 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than

approximately 100

°C (212°F) when the engine is

started.

• Intake air temperature is higher than 60°C

(140

°F) when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is 100 Hz

or more.

Judgment Criteria

• Long-term fuel trim has continued to be higher

than +12.5 percent or 5 seconds.

or

• Short-term fuel trim has continued to be higher

than +17.6 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than

approximately 100

°C (212°F) when the engine is

started.

• Intake air temperature is higher than 60°C

(140

°F) when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C

(171

°F).

• Volume airflow sensor output frequency is 100 Hz

or less.

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DIAGNOSTIC TROUBLE CODE PROCEDURES

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Judgment Criteria

• Long-term fuel trim has continued to be higher

than +12.5 percent or 5 seconds.

or

• Short-term fuel trim has continued to be higher

than +22.3 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than 77°C

(171

°F).

• Under the closed loop air/fuel ratio control.

Judgment Criteria

• Long-term fuel trim has continued to be +12.5

percent for 5 seconds.

or

• Short-term fuel trim has continued to be +25.0

percent for 5 seconds.

.

TROUBLESHOOTING HINTS (The most likely

causes for this code to be set are: )

• Volume airflow sensor failed.

• Injector (Number 1, 3, 5) failed.

• Incorrect fuel pressure.

• Air drawn in from gaps in gasket, seals, etc.

• Right bank heated oxygen sensor failed.

• Engine coolant temperature sensor failed.

• Intake air temperature sensor failed.

• Barometric pressure sensor failed.

• Exhaust leak.

• Use of incorrect or contaminated fuel.

• PCM failed.

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Check the exhaust leaks.
Q: Are there any abnormalities?

YES : Go to Step 2.
NO : Repair it. Then go to Step 16.

STEP 2. Check the intake system vacuum leak.
Q: Are there any abnormalities?

YES : Go to Step 3.
NO : Repair it. Then go to Step 16.

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DIAGNOSTIC TROUBLE CODE PROCEDURES

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STEP 3. Using scan tool MB991502, check data list item 12:
Volume Airflow Sensor.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991502 to the data reading mode for item

12, Volume Airflow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°C

to 95

°C (176°F to 203°F).

• When idling, between 17 and 43 Hz (between 3.5 and

7.5 gm/s).

• When 2,500 r/min, between 64 and 104 Hz (between

13.6 and 19.6 gm/s).

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

YES : YES: Go to Step 4.
NO : Refer to , DTC P0101

− Volume Airflow Circuit Range/

Performance Problem

P.13Ac-2

, DTC P0102

−

Volume Airflow Circuit Low Input

P.13Ac-9

.

STEP 4. Using scan tool MB991502, check data list item 13:
Intake Air Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991502 to the data reading mode for item

13, Intake Air Temperature Sensor.

• The intake air 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 : Go to Step 5.
NO : Refer to , DTC P0111

− Intake Air Temperature Circuit

Range/Performance Problem

P.13Ac-44

, DTC P0112

− Intake Air Temperature Circuit Low Input

P.13Ac-50

,

DTC P0113

− Intake Air Temperature Circuit High

Input

P.13Ac-54

.

ACX01539

16-PIN

MB991502

AC

ACX01539

16-PIN

MB991502

AC

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DIAGNOSTIC TROUBLE CODE PROCEDURES

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STEP 5. Using scan tool MB991502, check data list item 21:
Engine Coolant Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991502 to the data reading mode for item

21, 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 : Go to Step 6.
NO : Refer to , DTC P0116

− Engine Coolant Temperature

Circuit Range/Performance Problem

P.13Ac-60

, DTC

P0117

− Engine Coolant Temperature Circuit Low

Input

P.13Ac-70

, DTC P0118

− Engine Coolant

Temperature Circuit High Input

P.13Ac-74

.

STEP 6. Using scan tool MB991502, check data list item 25:
Barometric Pressure Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991502 to the data reading mode for item

25, Barometric Pressure Sensor.

• When altitude is 0 m (0 foot), 101 kPa (29.8 in.Hg.).

• When altitude is 600 m (1,969 feet), 95 kPa (28.1

in.Hg.).

• When altitude is 1,200 m (3,937 feet), 88 kPa (26.0

in.Hg.).

• When altitude is 1,800 m (5,906 feet), 81 kPa (23.9

in.Hg.).

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

YES : Go to Step 7.
NO : Refer to , DTC P0106

− Barometric Pressure Circuit

Range/Performance Problem

P.13Ac-17

, DTC P0107

− Barometric Pressure Temperature Circuit Low Input

P.13Ac-22

, DTC P0108

− Barometric Pressure

Temperature Circuit High Input

P.13Ac-35

.

STEP 7. Check harness connector B-44 at injector
intermediate connector for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 8.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 16.

ACX01539

16-PIN

MB991502

AC

ACX01539

16-PIN

MB991502

AC

AK200949

3

4

7

8

1

2

5

6

B-44(B)

CONNECTOR: B-44

AB

HARNESS
CONNECTOR:
COMPONENT SIDE