Infiniti FX35 / FX45. Manual - part 520

DTC P0138, P0158 HO2S2

EC-841

< SERVICE INFORMATION >

[VK45DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

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.

DTC Confirmation Procedure

INFOID:0000000001326683

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

 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 2 minutes.

5.

Check 1st trip DTC.

6.

If 1st trip DTC is detected, go to 

EC-846, "Diagnosis Procedure"

.

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).

1.

Turn ignition switch ON and select “COOLAN TEMP/S” in “DATA MONITOR” mode with CONSULT-III.

2.

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

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.

Open engine hood.

8.

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

9.

Start engine and follow the instruction of CONSULT-III.
NOTE:
It will take at most 10 minutes until “COMPLETED” is displayed.

PBIB2376E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0138
0138
(Bank 1)

Heated oxygen sensor 2 
circuit high voltage

A)

An excessively high voltage from the sen-
sor is sent to ECM.

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2

P0158
0158
(Bank 2)

B)

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

• Harness or connectors

(The sensor circuit is open or shorted)

• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector

EC-842

< SERVICE INFORMATION >

[VK45DE]

DTC P0138, P0158 HO2S2

10. Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”.

If “NG” is displayed, refer to 

EC-846, "Diagnosis 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

INFOID:0000000001326684

PROCEDURE FOR MALFUNCTION B

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

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

8.

If NG, go to 

EC-846, "Diagnosis Procedure"

.

PBIB2024E

DTC P0138, P0158 HO2S2

EC-843

< SERVICE INFORMATION >

[VK45DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Wiring Diagram

INFOID:0000000001326685

BANK 1

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.

TBWM1330E

EC-844

< SERVICE INFORMATION >

[VK45DE]

DTC P0138, P0158 HO2S2

TER-

MI-

NAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

6

R

Heated oxygen sensor 2 
heater (Bank 1)

[Engine is running]
• Engine speed: Below 3,600 rpm after the fol-

lowing 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 - 1.0V

[Ignition switch: ON]
• Engine stopped
[Engine is running]
• Engine speed: Above 3,600 rpm

BATTERY VOLTAGE
(11 - 14V)

55

W/R

Heated oxygen sensor 2 
(Bank 1)

[Engine is running]
• Revving engine from idle to 3,000 rpm quick-

ly after the following conditions are met

- Engine: After warming up
- After 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

78

B/R

Sensor ground
(Heated oxygen sensor 2)

[Engine is running]
• Warm-up condition
• Idle speed

Approximately 0V