Infiniti M35/M45 Y50. Manual - part 456

DTC P0138, P0158 HO2S2

EC-297

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Removal and Installation

NBS004XI

HEATED OXYGEN SENSOR 2

Refer to 

EM-28, "EXHAUST MANIFOLD"

 .

EC-298

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DTC P0139, P0159 HO2S2

DTC P0139, P0159 HO2S2

PFP:226A0

Component Description

NBS004XJ

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 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.

CONSULT-II Reference Value in Data Monitor Mode

NBS004XK

Specification data are reference values.

On Board Diagnosis Logic

NBS004XL

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 the various driving condition
such as fuel-cut.

SEF327R

MONITOR ITEM

CONDITION

SPECIFICATION

HO2S2 (B1)
HO2S2 (B2)

●

Revving engine from idle to 3,000 rpm quickly after the following conditions 
are met

–

Engine: After warming up

–

Keeping engine speed between 3,500 and 4,000 rpm for 1 minute and at idle 
for 1 minute under no load

0 - 0.3V 

←→

 Approx. 0.6 - 

1.0V

HO2S2 MNTR (B1)
HO2S2 MNTR (B2)

LEAN 

←→

 RICH

SEF302U

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0139
0139
(Bank 1)

Heated oxygen sensor 
2 circuit slow response

It takes more time for the sensor to respond 
between 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
0159
(Bank 2)

DTC P0139, P0159 HO2S2

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DTC Confirmation Procedure

NBS004XM

NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.

 WITH CONSULT-II

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

°

C (32 to 86 

°

F).

1.

Turn ignition switch ON and select “DATA MONITOR” mode with
CONSULT-II.

2.

Start engine and warm it up to the normal operating tempera-
ture.

3.

Turn ignition switch OFF and wait at least 10 seconds.

4.

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

5.

Let engine idle for 1 minute.

6.

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).

7.

Open engine hood.

8.

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

9.

Start engine and following the instruction of CONSULT-II.

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

10. Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”.

If “NG” is displayed, refer to 

EC-304, "Diagnostic Procedure"

 .

If “CAN NOT BE DIAGNOSED” is displayed, perform the following.

a.

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

b.

Return to step 1.

Overall Function Check

NBS004XN

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

 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.

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.

Set voltmeter probes between ECM terminal 55 [HO2S2 (B2) signal] or 74 [HO2S2 (B1) signal] and
ground.

SEF174Y

PBIB2374E

EC-300

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DTC P0139, P0159 HO2S2

6.

Check the voltage when revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
A change of voltage should be more than 0.24V for 1 sec-
ond during this procedure.
If the voltage can be confirmed in step 6, step 7 is not nec-
essary.

7.

Keep vehicle at idling for 10 minutes, then check the voltage. Or
check the voltage when coasting from 80 km/h (50 MPH) in D
position.
A change of voltage should be more than 0.24V for 1 sec-
ond during this procedure.

8.

If NG, go to 

EC-304, "Diagnostic Procedure"

 .

PBIB1607E