Infiniti QX56 (Z62). Manual - part 567

EC-246

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0137, P0157 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-246, "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:0000000006217816

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

P0137, P0157 HO2S2

EC-247

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

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EC

N

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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)]

EC-248

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0137, P0157 HO2S2

6.

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

P0138, P0158 HO2S2

EC-249

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

P0138, P0158 HO2S2

DTC Logic

INFOID:0000000006217817

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 oxygen storage capacity of the three way catalyst (manifold) causes the longer switching
time.
MALFUNCTION A
To judge the malfunctions of heated oxygen sensor 2, ECM monitors
whether the voltage is unusually high during various driving condi-
tions such as fuel cut.

MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors
whether the minimum voltage of sensor is sufficiently low during var-
ious driving conditions such as fuel cut.

DTC CONFIRMATION PROCEDURE

PBIB1848E

PBIB2376E

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0138

HO2S2 (B1)
[Heated oxygen sensor 2 
(bank 1) circuit high voltage]

A)

An excessively high voltage from the 
sensor is sent to ECM.

• Harness or connectors

(The heated oxygen sensor 2 circuit is 
open or shorted)

• Heated oxygen sensor 2

B)

The minimum voltage from the sensor is 
not reached to the specified voltage.

• Harness or connectors

(The heated oxygen sensor 2 circuit is 
open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector

P0158

HO2S2 (B2)
[Heated oxygen sensor 2 
(bank 2) circuit high voltage]

A)

An excessively high voltage from the 
sensor is sent to ECM.

• Harness or connectors

(The heated oxygen sensor 2 circuit is 
open or shorted)

• Heated oxygen sensor 2

B)

The minimum voltage from the sensor is 
not reached to the specified voltage.

• Harness or connectors

(The heated oxygen sensor 2 circuit is 
open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector