Infiniti FX35, FX50 (S51). Manual - part 672

P0139, P0159 HO2S2

EC-229

< DTC/CIRCUIT DIAGNOSIS >

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P0139, P0159 HO2S2

Description

INFOID:0000000005236829

The heated oxygen sensor 2, after three way catalyst 1, monitors the
oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1 V in richer conditions to 0 V in leaner con-
ditions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.

DTC Logic

INFOID:0000000005236830

DTC DETECTION LOGIC

The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity of the three way catalyst 1 causes the longer
switching time. To judge the malfunctions of heated oxygen sensor
2, ECM monitors whether the switching response of the sensor's
voltage is faster than specified during various driving conditions such
as fuel cut.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next test.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

Will CONSULT-III be used?

YES

>> GO TO 2.

NO

>> GO TO 4.

2.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT-III

TESTING CONDITION:
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30 

°

C (32 to 86 

°

F).

1.

Start engine and warm it up to the normal operating temperature.

2.

Turn ignition switch OFF and wait at least 10 seconds.

SEF327R

SEF302U

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0139

Heated oxygen sensor 2 
(bank 1) circuit slow re-
sponse

It takes more time for the sensor to respond be-
tween rich and lean than the specified time.

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector
• Intake air leaks

P0159

Heated oxygen sensor 2 
(bank 2) circuit slow re-
sponse

EC-230

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P0139, P0159 HO2S2

3.

Turn ignition switch ON.

4.

Turn ignition switch OFF and wait at least 10 seconds.

5.

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

6.

Let engine idle for 1 minute.

7.

Select “DATA MONITOR” mode with CONSULT-III.

8.

Make sure that “COOLAN TEMP/S” indicates more than 70

°

C (158

°

F).

If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches to 70

°

C (158

°

F).

9.

Open engine hood.

10. Select “HO2S2 (B1) P0139” or “HO2S2 (B2) P0159” of “HO2S2” in “DTC WORK SUPPORT” mode with

CONSULT-III.

11. Start engine and follow the instruction of CONSULT-III display.

NOTE:
It will take at most 10 minutes until “COMPLETED” is displayed.

12. Touch “SELF-DIAG RESULTS”.

Which is displayed on CONSULT-III screen?

OK

>> INSPECTION END

NG

>> Go to 

EC-231, "Diagnosis Procedure"

.

CAN NOT BE DIAGNOSED>>GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE AGAIN

1.

Turn ignition switch OFF and leave the vehicle in a cool place (soak the vehicle).

2.

Perform DTC confirmation procedure again.

>> GO TO 2.

4.

PERFORM COMPONENT FUNCTION CHECK

Without CONSULT-III

Perform component function check. Refer to 

EC-230, "Component Function Check"

.

NOTE:
Use component function check to check the overall function of the heated oxygen sensor 2 circuit. During this
check, a 1st trip DTC might not be confirmed.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Go to 

EC-231, "Diagnosis Procedure"

.

Component Function Check

INFOID:0000000005236831

1.

PERFORM COMPONENT FUNCTION CHECK-I

Without CONSULT-III

1.

Start engine and warm it up to the normal operating temperature.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Turn ignition switch OFF and wait at least 10 seconds.

5.

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

6.

Let engine idle for 1 minute.

7.

Check the voltage between ECM harness connector terminals under the following condition.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 2.

2.

PERFORM COMPONENT FUNCTION CHECK-II

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F102

76

84

Revving up to 4,000 rpm under no load at 
least 10 times

A change of voltage should be more than 
0.24 V for 1 second during this procedure.

P0159

80

P0139, P0159 HO2S2

EC-231

< DTC/CIRCUIT DIAGNOSIS >

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Check the voltage between ECM harness connector terminals under the following condition.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 3.

3.

PERFORM COMPONENT FUNCTION CHECK-III

Check the voltage between ECM harness connector terminals under the following condition.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Go to 

EC-231, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000005236832

1.

CHECK GROUND CONNECTION

1.

Turn ignition switch OFF.

2.

Check ground connection M95. Refer to Ground Inspection in 

GI-39, "Circuit Inspection"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace ground connection.

2.

CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

1.

Clear the mixture ratio self-learning value. Refer to 

EC-28, "MIXTURE RATIO SELF-LEARNING VALUE

CLEAR : Special Repair Requirement"

.

2.

Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? Is it difficult to start engine?

YES

>> Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to 

EC-235, "DTC Logic"

or 

EC-239, "DTC Logic"

.

NO

>> GO TO 3.

3.

CHECK HEATED OXYGEN SENSOR 2 (HO2S2) GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect HO2S2 harness connector.

3.

Disconnect ECM harness connector.

4.

Check the continuity between HO2S2 harness connector and ECM harness connector.

5.

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

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F102

76

84

Keeping engine at idle for 10 minutes

A change of voltage should be more than 
0.24 V for 1 second during this procedure.

P0159

80

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F102

76

84

Coasting from 80 km/h (50 MPH) in D po-
sition

A change of voltage should be more than 
0.24 V for 1 second during this procedure.

P0159

80

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F54

1

F102

84

Existed

P0159

2

F53

1

EC-232

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P0139, P0159 HO2S2

Is the inspection result normal?

YES

>> GO TO 4.

NO

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

4.

CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check the continuity between HO2S2 harness connector and ECM harness connector.

2.

Check the continuity between HO2S2 harness connector or ECM harness connector and ground.

3.

Also check harness for short to power.

Is the inspection result normal?

YES

>> GO TO 5.

NO

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

5.

CHECK HEATED OXYGEN SENSOR 2

Refer to 

EC-232, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

6.

REPLACE HEATED OXYGEN SENSOR 2

Replace malfunctioning heated oxygen sensor 2.

CAUTION:

• Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7

in) onto a hard surface such as a concrete floor; use a new one.

• Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread

Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant
(commercial service tool).

>> INSPECTION END

7.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-36, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000005236833

1.

INSPECTION START

Will CONSULT-III be used?

Will CONSULT-III be used?

YES

>> GO TO 2.

NO

>> GO TO 3.

2.

CHECK HEATED OXYGEN SENSOR 2 (HO2S2)

With CONSULT-III

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F54

4

F102

76

Existed

P0159

2

F53

4

80

DTC

HO2S2

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F54

4

F102

76

Ground

Not existed

P0159

2

F53

4

80