Infiniti QX56 (Z62). Manual - part 568

EC-250

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0138, P0158 HO2S2

1.

PRECONDITIONING

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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A

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 2 minutes.

7.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-251, "Diagnosis Procedure"

.

NO-1

>> With CONSULT-III: GO TO 3.

NO-2

>> With GST: GO TO 5.

3.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B

 WITH CONSULT-III

NOTE:
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.

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.

Check 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 70

°

C (158

°

F).

9.

Open engine hood.

10. Select “HO2S2 (B1) P1146” (for DTC P0138) or “HO2S2 (B2) P1166” (for DTC P0158) of “HO2S2” in

“DTC WORK SUPPORT” mode with CONSULT-III.

11. 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-251, "Diagnosis Procedure"

.

CON NOT BE DIAGNOSED>>GO TO 4.

4.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B 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 3.

5.

PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B

 WITH GST

Perform component function check. Refer to 

EC-251, "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?

P0138, P0158 HO2S2

EC-251

< DTC/CIRCUIT DIAGNOSIS >

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YES

>> INSPECTION END

NO

>> Go to 

EC-251, "Diagnosis Procedure"

.

Component Function Check

INFOID:0000000006217818

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.

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 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.

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-251, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006217819

1.

INSPECTION START

Confirm the detected malfunction (A or B). Refer to 

EC-249, "DTC Logic"

.

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0138

F110

96

100

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

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

P0158

87

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0138

F110

96

100

Keeping engine at idle for 10 minutes

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

P0158

87

DTC

ECM

Condition

Voltage

Connector

+

–

Terminal

Terminal

P0138

F110

96

100

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

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

P0158

87

EC-252

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0138, P0158 HO2S2

Which malfunction is detected?

A

>> GO  TO  2

B

>> GO  TO  8.

2.

CHECK HEATED OXYGEN SENSOR 2 CONNECTOR

1.

Disconnect heated oxygen sensor 2 (HO2S2) harness connector.

2.

Check that water is not inside connectors.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace harness or connectors.

3.

CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT

1.

Disconnect ECM harness connector.

2.

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

3.

Also check harness for short to ground and 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 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.

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-254, "Component Inspection (HO2 sensor 2)"

.

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. Refer to 

EM-40, "Exploded View"

.

CAUTION:

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

1

F110

100

Existed

P0158

2

F88

1

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

4

F110

96

Existed

P0158

2

F88

4

87

DTC

HO2S2

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

4

F110

96

Ground

Not existed

P0158

2

F88

4

87

P0138, P0158 HO2S2

EC-253

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

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• 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-40, "Intermittent Incident"

.

>> INSPECTION END

8.

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 P0172 or P0175 detected? Is it difficult to start engine?

YES

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

EC-267, "DTC Logic"

.

NO

>> GO TO 9.

9.

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 10.

NO

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

10.

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.

3.

Also check harness for short to power.

Is the inspection result normal?

YES

>> GO TO 11.

NO

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

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

1

F110

100

Existed

P0158

2

F88

1

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

4

F110

96

Existed

P0158

2

F88

4

87

DTC

HO2S2

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0138

1

F87

4

F110

96

Ground

Not existed

P0158

2

F88

4

87