Nissan Pathfinder (2006 year). Manual - part 178

DTC P0138, P0158 HO2S2

EC-283

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EC

2006 Pathfinder

Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

25

P

Heated oxygen sensor 2 
heater (Bank 1)

[Engine is running]

●

Engine speed: Below 3,600 rpm after the 
following conditions are met

–

Engine: After warming up

–

Keeping the engine speed between 3,500 
and 4,000 rpm for 1 minute and at idle for 1 
minute under no load

0 - 1.0V

[Ignition switch: ON]

●

Engine: Stopped

[Engine is running]

●

Engine speed: Above 3,600 rpm

BATTERY VOLTAGE
(11 - 14V)

74

W

Heated oxygen sensor 2 
(Bank 1)

[Engine is running]

●

Revving engine from idle to 3,000 rpm 
quickly after the following conditions are met

–

Engine: After warming up

–

Keeping the engine speed between 3,500 
and 4,000 rpm for 1 minute and at idle for 1 
minute under no load

0 - Approximately 1.0V

78

GR

Sensor ground
(Heated oxygen sensor 2)

[Engine is running]

●

Warm-up condition

●

Idle speed

Approximately 0V

EC-284

DTC P0138, P0158 HO2S2

2006 Pathfinder

BANK 2

BBWA2367E

DTC P0138, P0158 HO2S2

EC-285

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EC

2006 Pathfinder

Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

Diagnostic Procedure

UBS00K6Y

PROCEDURE FOR MALFUNCTION A

1. 

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body. Refer to 

EC-151, "Ground Inspection"

 .

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

6

R

Heated oxygen sensor 2 
heater (Bank 2)

[Engine is running]

●

Engine speed: Below 3,600 rpm after the 
following conditions are met

–

Engine: After warming up

–

Keeping the engine speed between 3,500 
and 4,000 rpm for 1 minute and at idle for 1 
minute under no load

0 - 1.0V

[Ignition switch: ON]

●

Engine: Stopped

[Engine is running]

●

Engine speed: Above 3,600 rpm

BATTERY VOLTAGE
(11 - 14V)

55

G

Heated oxygen sensor 2 
(Bank 2)

[Engine is running]

●

Revving engine from idle to 3,000 rpm 
quickly after the following conditions are met

–

Engine: After warming up

–

Keeping the engine speed between 3,500 
and 4,000 rpm for 1 minute and at idle for 1 
minute under no load

0 - Approximately 1.0V

78

GR

Sensor ground
(Heated oxygen sensor 2)

[Engine is running]

●

Warm-up condition

●

Idle speed

Approximately 0V

BBIA0539E

EC-286

DTC P0138, P0158 HO2S2

2006 Pathfinder

2. 

CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT

1.

Disconnect heated oxygen sensor 2 harness connector.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between HO2S2 terminal 4 and ECM terminal 78.
Refer to Wiring Diagram.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 3.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

Continuity should exist.

BBIA0540E

DTC P0138, P0158 HO2S2

EC-287

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EC

2006 Pathfinder

3. 

CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.

2.

Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 4.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

4. 

CHECK HO2S2 CONNECTOR FOR WATER

Check connectors for water.

OK or NG

OK

>> GO TO 5.

NG

>> Repair or replace harness or connectors.

5. 

CHECK HEATED OXYGEN SENSOR 2

Refer to 

EC-290, "Component Inspection"

 .

OK or NG

OK

>> GO TO 6.

NG

>> Replace malfunctioning heated oxygen sensor 2.

6. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-144, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

DTC

Terminals

Bank

ECM

Sensor

P0138

74

1

1

P0158

55

1

2

Continuity should exist.

DTC

Terminals

Bank

ECM

Sensor

P0138

74

1

1

P0158

55

1

2

Continuity should not exist.

Water should not exist.

EC-288

DTC P0138, P0158 HO2S2

2006 Pathfinder

PROCEDURE FOR MALFUNCTION B

1. 

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body. Refer to 

EC-151, "Ground Inspection"

 .

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2. 

CLEAR THE SELF-LEARNING DATA

 With CONSULT-II

1.

Start engine and warm it up to normal operating temperature.

2.

Select “SELF-LEARNING CONT” in “WORK SUPPORT” mode
with CONSULT-II.

3.

Clear the self-learning control coefficient by touching “CLEAR”.

4.

Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 or P0175 detected?
Is it difficult to start engine?

 Without CONSULT-II

1.

Start engine and warm it up to normal operating temperature.

2.

Turn ignition switch OFF.

3.

Disconnect mass air flow sensor harness connector, and restart
and run engine for at least 5 seconds at idle speed.

4.

Stop engine and reconnect mass air flow sensor harness con-
nector.

5.

Make sure DTC P0102 is displayed.

6.

Erase the DTC memory. Refer to 

EC-60, "HOW TO ERASE

EMISSION-RELATED DIAGNOSTIC INFORMATION"

 .

7.

Make sure DTC P0000 is displayed.

8.

Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 or P0175 detected?
Is it difficult to start engine?

Yes or No

Yes

>> Perform trouble diagnosis for DTC P0172, P0175. Refer to 

EC-317, "DTC P0172, P0175 FUEL

INJECTION SYSTEM FUNCTION"

 .

No

>> GO TO 3.

BBIA0539E

SEF968Y

BBIA0541E

DTC P0138, P0158 HO2S2

EC-289

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EC

2006 Pathfinder

3. 

CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect heated oxygen sensor 2 harness connector.

3.

Disconnect ECM harness connector.

4.

Check harness continuity between HO2S2 terminal 4 and ECM terminal 78.
Refer to Wiring Diagram.

5.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 4.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

Continuity should exist.

BBIA0540E

EC-290

DTC P0138, P0158 HO2S2

2006 Pathfinder

4. 

CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.

2.

Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 5.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

5. 

CHECK HEATED OXYGEN SENSOR 2

Refer to 

EC-290, "Component Inspection"

 .

OK or NG

OK

>> GO TO 6.

NG

>> Replace malfunctioning heated oxygen sensor 2.

6. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-144, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

Component Inspection

UBS00K6Z

HEATED OXYGEN SENSOR 2

 With CONSULT-II

1.

Turn ignition switch ON and select “DATA MONITOR” mode with
CONSULT-II.

2.

Start engine and warm it up to the normal operating tempera-
ture.

3.

Turn ignition switch OFF and wait at least 10 seconds.

4.

Start engine and keep the engine speed between 3,500 and
4,000 rpm for at least 1 minute under no load.

5.

Let engine idle for 1 minute.

DTC

Terminals

Bank

ECM

Sensor

P0138

74

1

1

P0158

55

1

2

Continuity should exist.

DTC

Terminals

Bank

ECM

Sensor

P0138

74

1

1

P0158

55

1

2

Continuity should not exist.

SEF174Y