Mitsubishi Montero (2002-2004). Manual — part 675

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-397

STEP 10. Check for harness damage between MFI relay
connector B-22X (terminal No. 1) and EGR valve connector
B-56 (terminal No. 2, No. 5).
Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO : Repair it. Then go to Step 12.

AK200951

2 1

3

4

B-22X

AB

CONNECTOR: B-22X

HARNESS
CONNECTOR:
COMPONENT SIDE

AK200967

1

2

3

4

5

6

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

B-56(GR)

CONNECTOR: B-56

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-398

STEP 11. Check for harness damage between EGR valve
connector B-56 and PCM connector D-132.

a. EGR valve connector B-56 (terminal No. 1) and PCM con-

nector D-132 (terminal No. 3).

b. EGR valve connector B-56 (terminal No. 3) and PCM con-

nector D-132 (terminal No. 12).

c. EGR valve connector B-56 (terminal No. 4) and PCM con-

nector D-132 (terminal No. 19).

d. EGR valver connector B-56 (terminal No. 6) and PCM con-

nector D-132 (terminal No. 26).

Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 12.
NO : Repair it. Then go to Step 12.

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 P0403 set?

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

DTC P0421: Warm up catalyst Efficiency Below Threshold (bank 1)

.

TECHNICAL DESCRIPTION

• The signal from the rear heated oxygen sensor

differs from the front heated oxygen sensor. That
is because the catalytic converter purifies
exhaust gas. When the catalytic converter has
deteriorated, the signal from the front heated oxy-
gen sensor becomes similar to the rear heated
oxygen sensor.

• The PCM compares the output of the front and

rear heated oxygen sensor signals.

.

DTC SET CONDITIONS

Check Conditions

• Engine speed is lower than 3,000 r/min.

• The throttle valve is open.

• Volume airflow sensor output frequency is

between 69 and 169 Hz.

• More than 3 seconds has elapsed after the

above-mentioned three conditions have been
met.

• Intake air temperature is higher than −10°C

(14

°F).

AK200967

1

2

3

4

5

6

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

B-56(GR)

CONNECTOR: B-56

AK200938

2

3

4

5

6

7

8

9

1

10

14

15

16

17

18

19

20

21

22

23

24

25

26

27

11

12

13

AB

CONNECTOR: D-132

HARNESS CONNECTOR:
COMPONENT SIDE

PCM

D-132(GR)

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-399

• Barometric pressure is higher than 76 kPa (11

psi).

• Under the closed loop air/fuel ratio control.

• Vehicle speed is 1.5 km/h (0.93 mph) or more.

• The PCM monitors for this condition for 7 cycles

of 12 seconds each during the drive cycle.

• Short-term fuel trim is higher than −30 percent

and lower than +25 percent.

• The cumulative volume airflow sensor output fre-

quency for every 2 seconds is higher than 4,000
Hz.

Judgment Criteria

• The right bank heated oxygen sensor (rear) sig-

nal frequency devided by right bank heated oxy-
gen sensor (front) signal frequency = 0.75 or
more.

.

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

• Right bank side catalytic converter deteriorated.

• Right bank heated oxygen sensor failed.

• 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 7.

STEP 2. Using scan tool MB991502, check data list item 69:
Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).

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

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

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

output voltage should repeat 0 volt 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 : Go to Step 3.
NO : Refer to DTC P0136

− Heated Oxygen Sensor Circuit

(Bank 1, Sensor 2)

P.13Ac-151

, DTC P0137

− Heated

Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor
2)

P.13Ac-166

, DTC P0138

− Heated Oxygen Sensor

Circuit High Voltage (Bank 1, Sensor 2)

P.13Ac-172

,

DTC P0139

− Heated Oxygen Sensor Circuit Slow

Response (Bank 1, Sensor 2)

P.13Ac-176

.

ACX01539

16-PIN

MB991502

AC

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DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-400

STEP 3. Using scan tool MB991502, check data list item 39:
Heated Oxygen Sensor Bank 1, Sensor 2 (right front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991502 to the data reading mode for item

39, Heated Oxygen Sensor Bank 1, Sensor 2 (right front).

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

output voltage should be 0.6 to 1.0 volt.

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

YES : Go to Step 4.
NO : Refer to DTC P0130

− Heated Oxygen Sensor Circuit

(Bank 1, Sensor 1)

P.13Ac-105

, DTC P0131

− Heated

Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor
1)

P.13Ac-120

, DTC P0132

− Heated Oxygen Sensor

Circuit High Voltage (Bank 1, Sensor 1)

P.13Ac-126

,

DTC P0133

− Heated Oxygen Sensor Circuit Slow

Response (Bank 1, Sensor 1)

P.13Ac-130

, DTC

P0134

− Heated Oxygen Sensor Circuit No Activity

Detected (Bank 1, Sensor 1)

P.13Ac-133

.

STEP 4. Using scan tool MB991502, 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 MB991502 to the data reading mode for item

39, Heated Oxygen Sensor Bank 1, Sensor 1 (right front).

(3) Keep the engine speed at 2,000 r/min.

• 0 − 0.4 and 0.6 − 1.0 volt should alternate 15 times or

more within 10 seconds.

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

YES : Go to Step 5.
NO : Replace the right bank heated oxygen sensor (front).

Then go to Step 7.

STEP 5. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to

GROUP 13A, Procedure 3

− Catalytic Converter Monitor

P.13Ab-2

.

(2) Read the diagnostic trouble code.
Q: Is DTC P0421 set?

YES : Replace the right bank side catalytic converter. Then

go to Step 6.

NO : The inspection is complete.

ACX01539

16-PIN

MB991502

AC

ACX01539

16-PIN

MB991502

AC