Infiniti FX35 / FX45. Manual - part 373

DTC P0137, P0157 HO2S2

EC-253

< SERVICE INFORMATION >

[VQ35DE]

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.)
The voltage should be above 0.68V at least once during this
procedure.
If the voltage is above 0.68V at step 6, step 7 is not neces-
sary.

Keep vehicle at idling for 10 minutes, then check voltage. Or
check the voltage when coasting from 80 km/h (50 MPH) in D
position.
The voltage should be below 0.18V at least once during this
procedure.

If NG, replace 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 tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.

Removal and Installation

INFOID:0000000001326082

HEATED OXYGEN SENSOR 2

Refer to

EM-26

PBIB1607E

EC-254

< SERVICE INFORMATION >

[VQ35DE]

DTC P0138, P0158 HO2S2

DTC P0138, P0158 HO2S2

Component Description

INFOID:0000000001326083

The heated oxygen sensor 2 (HO2S2), 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-III Reference Value in Data Monitor Mode

INFOID:0000000001326084

Specification data are reference values.

On Board Diagnosis Logic

INFOID:0000000001326085

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 1 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 the various driving con-
dition 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 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 the 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

PBIB1848E

PBIB2376E

DTC P0138, P0158 HO2S2

EC-255

< SERVICE INFORMATION >

[VQ35DE]

DTC Confirmation Procedure

INFOID:0000000001326086

Perform PROCEDURE FOR MALFUNCTION A first.
If DTC cannot be confirmed, perform PROCEDURE FOR MALFUNCTION B.
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.

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.

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.

If 1st trip DTC is detected, go to “PROCEDURE FOR MALFUNCTION A”.

PROCEDURE FOR MALFUNCTION B

With CONSULT-III

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-III.

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.

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).

Open engine hood.

Select “HO2S2 (B1) P1146” (for DTC P0138) or “HO2S2 (B2) P1166” (for DTC P0158) of “HO2S2” in
“DTC WORK SUPPORT” mode with CONSULT-III.

Start engine and following the instruction of CONSULT-III.
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 “PROCEDURE FOR MALFUNCTION B”.
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

INFOID:0000000001326087

PROCEDURE FOR MALFUNCTION B

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 sen-
sor is sent to ECM.

• Harness or connectors

(Heated oxygen sensor 2 circuit is open
or shorted)

• Heated oxygen sensor 2

P0158
0158
(Bank 2)

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

• Harness or connectors

(Heated oxygen sensor 2 circuit is open
or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector

EC-256

< SERVICE INFORMATION >

[VQ35DE]

DTC P0138, P0158 HO2S2

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

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 55 [HO2S2 (B2) signal] or 74 [HO2S2 (B1) signal] and
ground.

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

If NG, go to

EC-255, "DTC Confirmation Procedure"

PBIB1607E

Content .. 371 372 373 374 ..