Infiniti FX35 / FX45. Manual - part 522

DTC P0138, P0158 HO2S2

EC-849

< SERVICE INFORMATION >

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2.

Disconnect heated oxygen sensor 2 harness connector.

3.

Disconnect ECM harness connector.

4.

Check harness continuity between HO2S2 terminal 4 and ECM terminal 78.
Refer to Wiring Diagram.

5.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 4.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

4.

CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.

2.

Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 5.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

5.

CHECK HEATED OXYGEN SENSOR 2

Refer to 

EC-850, "Component Inspection"

.

OK or NG

OK

>> GO TO 6.

NG

>> Replace malfunctioning heated oxygen sensor 2.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

EC-717

.

Continuity should exist.

PBIB1534E

DTC

Terminals

Bank

ECM

Sensor

P0138

55

1

1

P0158

74

1

2

Continuity should exist.

DTC

Terminals

Bank

ECM

Sensor

P0138

55

1

1

P0158

74

1

2

Continuity should not exist.

EC-850

< SERVICE INFORMATION >

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DTC P0138, P0158 HO2S2

>> INSPECTION END

Component Inspection

INFOID:0000000001326687

HEATED OXYGEN SENSOR 2

 With CONSULT-III

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.

Select “FUEL INJECTION” in “ACTIVE TEST” mode with CONSULT-III, and select “HO2S2 (B1)/(B2)” as
the monitor item.

6.

Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to 

±

25%.

“HO2S2 (B1)/(B2)” should be above 0.78V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 0.18V at least once when the “FUEL INJECTION” is 

−

25%.

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.

 Without CONSULT-III

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

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.)
The voltage should be above 0.78V at least once during this
procedure.
If the voltage is above 0.78V at step 6, step 7 is not neces-
sary.

7.

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.

8.

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.

JMBIA0640GB

PBIB2024E

DTC P0138, P0158 HO2S2

EC-851

< SERVICE INFORMATION >

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Removal and Installation

INFOID:0000000001326688

HEATED OXYGEN SENSOR 2

Refer to 

EM-179

.

EC-852

< SERVICE INFORMATION >

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DTC P0139, P0159 HO2S2

DTC P0139, P0159 HO2S2

Component Description

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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 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

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Specification data are reference values.

On Board Diagnosis Logic

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The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the A/F sensor 1. The oxygen storage
capacity of 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 sensor's
voltage is faster than specified during the various driving condition
such as fuel-cut.

DTC Confirmation Procedure

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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.

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)

• 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

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 be-
tween 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)