Infiniti M45 (Y34). Manual - part 389

DTC P0138, P0158 HO2S2

EC-245

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DTC P0138, P0158 HO2S2

PFP:226A0

Component Description

ABS002HC

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 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

ABS002HD

Specification data are reference values.

On Board Diagnosis Logic

ABS002HE

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 voltage is unusually high during
the various driving condition such as fuel-cut.

SEF327R

MONITOR ITEM

CONDITION

SPECIFICATION

HO2S2 (B1)
HO2S2 (B2)

●

Warm-up condition

●

After 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)
HO2S2 MNTR (B2)

●

Warm-up condition

●

After 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

PBIB1877E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0138
0138
(Bank 1)

Heated oxygen sensor 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

P0158
0158
(Bank 2)

EC-246

DTC P0138, P0158 HO2S2

DTC Confirmation Procedure

ABS002HF

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

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 2 minutes.

6.

If 1st trip DTC is detected, go to 

EC-250, "Diagnostic Procedure"

.

 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 2 minutes.

5.

Turn ignition switch OFF and wait at least 10 seconds.

6.

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

7.

Let engine idle for 2 minutes.

8.

Select “MODE 3” with GST.

9.

If 1st trip DTC is detected, go to 

EC-250, "Diagnostic Procedure"

 .

●

When using GST, DTC Confirmation Procedure should be performed twice as much as when
using CONSULT-II because GST cannot display MODE 7 (1st trip DTC) concerning this diagno-
sis. Therefore, using CONSULT-II is recommended.

SEF174Y

DTC P0138, P0158 HO2S2

EC-247

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Wiring Diagram

ABS002HH

BANK 1

TBWA0276E

EC-248

DTC P0138, P0158 HO2S2

Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

123

PU

Heated oxygen sensor 2 
(bank 1)

[Engine is running]

●

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

–

Warm-up condition

–

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

0 - Approximately 1.0V