Infiniti QX56 (Z62). Manual - part 570

EC-258

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0139, P0159 HO2S2

Which is displayed on CONSULT-III screen?

OK

>> INSPECTION END

NG

>> Go to 

EC-259, "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

 WITH GST

Perform component function check. Refer to 

EC-258, "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-259, "Diagnosis Procedure"

.

Component Function Check

INFOID:0000000006217822

1.

PERFORM COMPONENT FUNCTION CHECK-I

 WITH GST

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.

Restart 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 conditions.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 2.

2.

PERFORM COMPONENT FUNCTION CHECK-II

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 3.

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F110

96

100

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

87

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F110

96

100

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

87

P0139, P0159 HO2S2

EC-259

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

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EC

N

P

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3.

PERFORM COMPONENT FUNCTION CHECK-III

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Go to 

EC-259, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006217823

1.

CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

1.

Clear the mixture ratio self-learning value. Refer to 

EC-152, "Work Procedure"

.

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-263, "DTC Logic"

or 

EC-267, "DTC Logic"

.

NO

>> GO TO 2.

2.

CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect heated oxygen sensor 2 (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.

Is the inspection result normal?

YES

>> GO TO 3.

NO

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

3.

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 and ground, or ECM harness connector and
ground.

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0139

F110

96

100

Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position

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

P0159

87

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F87

1

F110

100

Existed

P0159

2

F88

1

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F87

4

F110

96

Existed

P0159

2

F88

4

87

DTC

HO2S2

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F87

4

F110

96

Ground

Not existed

P0159

2

F88

4

87

EC-260

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0139, P0159 HO2S2

3.

Also check harness for short to power.

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 HEATED OXYGEN SENSOR 2

Refer to 

EC-260, "Component Inspection (HO2 sensor 2)"

.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> GO TO 5.

5.

REPLACE HEATED OXYGEN SENSOR 2

Replace malfunctioning heated oxygen sensor 2. Refer to 

EM-40, "Exploded View"

.

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

6.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection (HO2 sensor 2)

INFOID:0000000006217824

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

 WITH CONSULT-III

1.

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

2.

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

3.

Let engine idle for 1 minute.

4.

Select “FUEL INJECTION” in “ACTIVE TEST” mode, and select “HO2S2 (B1)/(B2)” as the monitor item
with CONSULT-III.

5.

Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to 

±

25%.

“HO2S2 (B1)/(B2)” should be above 0.74 V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 0.18 V at least once when the “FUEL INJECTION” is 

−

25%.

Is the inspection result normal?

YES

>> INSPECTION END

JMBIA1573GB

P0139, P0159 HO2S2

EC-261

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NO

>> GO TO 6.

3.

CHECK HEATED OXYGEN SENSOR 2-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.

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

4.

Let engine idle for 1 minute.

5.

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 4.

4.

CHECK HEATED OXYGEN SENSOR 2-II

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 5.

5.

CHECK HEATED OXYGEN SENSOR 2-III

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 6.

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

F110

96

[HO2S2 

(bank 1)]

100

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

The voltage should be above 0.74 V at 
least once during this procedure.
The voltage should be below 0.18 V at 
least once during this procedure.

87

[HO2S2 

(bank 2)]

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

F110

96

[HO2S2 

(bank 1)]

100

Keeping engine at idle for 10 minutes

The voltage should be above 0.74 V at 
least once during this procedure.
The voltage should be below 0.18 V at 
least once during this procedure.

87

[HO2S2 

(bank 2)]

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

F110

96

[HO2S2 

(bank 1)]

100

Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position

The voltage should be above 0.74 V at 
least once during this procedure.
The voltage should be below 0.18 V at 
least once during this procedure.

87

[HO2S2 

(bank 2)]