Infiniti FX35 / FX45. Manual - part 496

DTC P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER

EC-745

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Check resistance between terminals 3 and 4.

Check continuity between terminals 3 and 1, 2, 5, 6, terminals 4 and
1, 2, 5, 6.

If NG, replace the A/F sensor 1.

CAUTION:

• Discard any A/F 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 A/F sensor, clean exhaust system

threads using Heated Oxygen Sensor Thread Cleaner tool J-
43897-18 or J-43897-12 and approved anti-seize lubricant.

Removal and Installation

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AIR FUEL RATIO (A/F) SENSOR 1

Refer to 

EM-179

.

Resistance: 2.3 - 4.3

Ω

 [at 25

°

C (77

°

F)]

Continuity should not exist.

PBIB1684E

EC-746

< SERVICE INFORMATION >

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DTC P0037, P0038, P0057, P0058 HO2S2 HEATER

DTC P0037, P0038, P0057, P0058 HO2S2 HEATER

Description

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SYSTEM DESCRIPTION

The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature. 

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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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.
TESTING CONDITION:

Sensor

Input signal to ECM

ECM function

Actuator

Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)

Engine speed

Heated oxygen sensor 2 
heater control

Heated oxygen sensor 2 heater

Engine coolant temperature sensor

Engine coolant temperature

Mass air flow sensor

Amount of intake air

Engine speed rpm

Heated oxygen sensor 2 heater

Above 3,600

OFF

Below 3,600 rpm 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

ON

MONITOR ITEM

CONDITION

SPECIFICATION

HO2S2 HTR (B1)
HO2S2 HTR (B2)

• Engine speed: Below 3,600 rpm 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

ON

• Engine speed: Above 3,600 rpm

OFF

DTC No.

Trouble diagnosis 

name

DTC detecting condition

Possible cause

P0037
0037
(Bank 1)

Heated oxygen 
sensor 2 heater 
control circuit low

The current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM 
through the heated oxygen sensor 2 heater.)

• Harness or connectors

(The heated oxygen sensor 2 heater circuit is 
open or shorted.)

• Heated oxygen sensor 2 heater

P0057
0057
(Bank 2)

P0038
0038
(Bank 1)

Heated oxygen 
sensor 2 heater 
control circuit high

The current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM 
through the heated oxygen sensor 2 heater.)

• Harness or connectors

(The heated oxygen sensor 2 heater circuit is 
shorted.)

• Heated oxygen sensor 2 heater

P0058
0058
(Bank 2)

DTC P0037, P0038, P0057, P0058 HO2S2 HEATER

EC-747

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Before performing the following procedure, confirm that battery voltage is between 10.5V and 16V at
idle.
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 the engine and keep the engine speed between 3,500 rpm and 4,000 rpm for at least 1 minute under
no load.

4.

Let engine idle for 1 minute.

5.

Check 1st trip DTC.

6.

If 1st trip DTC is detected, go to 

EC-751, "Diagnosis Procedure"

.

EC-748

< SERVICE INFORMATION >

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DTC P0037, P0038, P0057, P0058 HO2S2 HEATER

Wiring Diagram

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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.

TBWM1325E