Nissan Frontier D22. Manual - part 278

DTC P0138 HO2S2

EC-215

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EC

Removal and Installation

UBS00D4Q

HEATED OXYGEN SENSOR 2

Refer to 

EX-3, "EXHAUST SYSTEM"

 .

EC-216

[KA24DE]

DTC P0139 HO2S2

DTC P0139 HO2S2

PFP:226A0

Component Description

UBS00D4R

 The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the heated oxygen sensor 1 are
shifted, the air-fuel ratio is controlled to stoichiometric, by the signal
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

UBS00D4S

Specification data are reference values.

On Board Diagnosis Logic

UBS00D4T

The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the heated oxygen sensor 1. The oxygen
storage capacity before the three way catalyst (manifold) causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the switching response of the sen-
sor's voltage is faster than specified during various driving conditions
such as fuel-cut.

SEF327R

MONITOR ITEM

CONDITION

SPECIFICATION

HO2S2 (B1)

●

Engine: After warming up

●

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

Revving engine from idle up to 3,000 
rpm quickly.

0 - 0.3V 

←→ Approx. 0.6 - 1.0V

HO2S2 MNTR (B1)

●

Engine: After warming up

●

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

Revving engine from idle up to 3,000 
rpm quickly.

LEAN 

←→ RICH

SEF302U

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0139

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

DTC P0139 HO2S2

EC-217

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EC

DTC Confirmation Procedure

UBS00ELT

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.

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

8.

Start engine and following the instruction of CONSULT-II.

9.

Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”.
If “NG” is displayed, refer to 

EC-220, "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

UBS00ELU

Use this procedure to check the overall function of the heated oxygen sensor 2 circuit. During this check, a
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 56 HO2S2 signal and engine ground.

SEF174Y

PBIB0115E

EC-218

[KA24DE]

DTC P0139 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 voltage change should be more than 0.06V for 1 second
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 voltage change should be more than 0.06V for 1 second
during this procedure.

8.

If NG, go to 

EC-220, "Diagnostic Procedure"

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AEC874A