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Infiniti FX35, FX50 (S51). Manual - part 821

P0137, P0157 HO2S2

EC-825

< DTC/CIRCUIT DIAGNOSIS >

[VK50VE]

Is the inspection result normal?

YES

>> INSPECTION END

>> GO TO 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

>> GO TO 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

ECM

Condition

Voltage

Connector

–

Terminal

F110

[HO2S2

(bank 1)]

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.

[HO2S2

(bank 2)]

EC-826

< DTC/CIRCUIT DIAGNOSIS >

[VK50VE]

P0138, P0158 HO2S2

P0138, P0158 HO2S2

Description

INFOID:0000000005237309

The heated oxygen sensor 2, after three way catalyst (manifold),
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:0000000005237310

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.

SEF327R

PBIB1848E

PBIB2376E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0138

Heated oxygen sensor 2
(bank 1) circuit high voltage

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

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2

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

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector

P0138, P0158 HO2S2

EC-827

< DTC/CIRCUIT DIAGNOSIS >

[VK50VE]

DTC CONFIRMATION PROCEDURE

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.

Turn ignition switch ON.

Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A

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

Turn ignition switch OFF and wait at least 10 seconds.

Turn ignition switch ON.

Turn ignition switch OFF and wait at least 10 seconds.

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

Let engine idle for 2 minutes.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to

EC-829, "Diagnosis Procedure"

NO-1

>> With CONSULT-III: GO TO 3.

NO-2

>> With GST: GO TO 5.

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).

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

Turn ignition switch OFF and wait at least 10 seconds.

Turn ignition switch ON.

Turn ignition switch OFF and wait at least 10 seconds.

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

Let engine idle for 1 minute.

Select “DATA MONITOR” mode with CONSULT-III.

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).

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?

>> INSPECTION END

>> Go to

EC-829, "Diagnosis Procedure"

CON NOT BE DIAGNOSED>>GO TO 4.

P0158

Heated oxygen sensor 2
(bank 2) circuit high voltage

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

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2

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

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

EC-828

< DTC/CIRCUIT DIAGNOSIS >

[VK50VE]

P0138, P0158 HO2S2

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B AGAIN

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

Perform DTC confirmation procedure again.

>> GO TO 3.

PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B

With GST

Perform component function check. Refer to

EC-828, "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

>> Go to

EC-829, "Diagnosis Procedure"

Component Function Check

INFOID:0000000005237311

PERFORM COMPONENT FUNCTION CHECK-I

With GST

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

Turn ignition switch OFF and wait at least 10 seconds.

Turn ignition switch ON.

Turn ignition switch OFF and wait at least 10 seconds.

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

Let engine idle for 1 minute.

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

Is the inspection result normal?

YES

>> INSPECTION END

>> GO TO 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

>> GO TO 3.

PERFORM COMPONENT FUNCTION CHECK-III

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

DTC

ECM

Condition

Voltage

Connector

–

Terminal

P0138

F110

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

DTC

ECM

Condition

Voltage

Connector

–

Terminal

P0138

F110

Keeping engine at idle for 10 minutes

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

P0158

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