Infiniti F50. Manual - part 403

DTC P0139, P0159 HO2S2

EC-253

DTC P0139, P0159 HO2S2

PFP:226A0

Component Description

EBS00MCD

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

EBS00MCE

Specification data are reference values.

On Board Diagnosis Logic

EBS00MCF

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 the various driving condi-
tion 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

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

●

Injectors

●

Intake air leaks

P0159
0159
(Bank 2)

EC-254

DTC P0139, P0159 HO2S2

DTC Confirmation Procedure

EBS00MCG

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).

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

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

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.

Make sure that “COOLAN TEMP/S” indicates more than 70

(158

F).

If not, warm up engine and go to next step when “COOLAN
TEMP/S” indication reaches to 70

C (158

F).

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

Start engine and following the instruction of CONSULT-II.

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

EC-259, "Diagnostic Procedure"

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

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

Return to step 1.

Overall Function Check

EBS00MCH

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

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

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.

Set voltmeter probes between ECM terminal 123 [HO2S2 (B1) signal] or 124 [HO2S2 (B2) signal] and
engine ground.

SEF174Y

PBIB0115E

DTC P0139, P0159 HO2S2

EC-255

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.

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.

If NG, go to

EC-259, "Diagnostic Procedure"

PBIB0068E

EC-256

DTC P0139, P0159 HO2S2

Wiring Diagram

EBS00MCI

BANK 1

TBWM0147E

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