Infiniti G37 Coupe. Manual - part 512

P0139, P0159 HO2S2

EC-229

< COMPONENT DIAGNOSIS >

[VQ37VHR]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> 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 the continuity between HO2S2 harness connector and ECM harness connector.

2.

Check the continuity between HO2S2 harness connector or ECM harness connector and ground.

3.

Also check harness for short to power.

Is the inspection result normal?

YES

>> GO TO 5.

NO

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

5.

CHECK HEATED OXYGEN SENSOR 2

Refer to 

EC-229, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

6.

REPLACE HEATED OXYGEN SENSOR 2

Replace malfunctioning 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.

>> INSPECTION END

7.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001910859

1.

INSPECTION START

Do you have CONSULT-III?

Do you have CONSULT-III?

YES

>> GO TO 2.

NO

>> GO TO 3.

2.

CHECK HEATED OXYGEN SENSOR 2

With CONSULT-III

1.

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

DTC

HO2S2

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F54

4

F102

76

Existed

P0159

2

F53

4

80

DTC

HO2S2

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0139

1

F54

4

F102

76

Ground

Not existed

P0159

2

F53

4

80

EC-230

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0139, P0159 HO2S2

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.

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

7.

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

±

25%.

“HO2S2 (B1)/(B2)” should be above 0.68V 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%.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 6.

3.

CHECK HEATED OXYGEN SENSOR 2-I

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.

Check the voltage between ECM harness connector and ground under the following condition.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 4.

4.

CHECK HEATED OXYGEN SENSOR 2-II

Check the voltage between ECM harness connector and ground under the following condition.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 5.

5.

CHECK HEATED OXYGEN SENSOR 2-III

Check the voltage between ECM harness connector and ground under the following condition.

PBIB3458E

ECM

Ground

Condition

Voltage

Connector

Terminal

F102

76

[HO2S2 (bank 1)]

Ground

Revving up to 4,000 rpm under no load at 
least 10 times

The voltage should be above 0.68V at 
least once during this procedure.
The voltage should be below 0.18V at least 
once during this procedure.

80

[HO2S2 (bank 2)]

ECM

Ground

Condition

Voltage

Connector

Terminal

F102

76

[HO2S2 (bank 1)]

Ground

Keeping engine at idle for 10 minutes

The voltage should be above 0.68V at 
least once during this procedure.
The voltage should be below 0.18V at least 
once during this procedure.

80

[HO2S2 (bank 2)]

P0139, P0159 HO2S2

EC-231

< COMPONENT DIAGNOSIS >

[VQ37VHR]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 6.

6.

REPLACE HEATED OXYGEN SENSOR 2

Replace malfunctioning 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.

>> INSPECTION END

ECM

Ground

Condition

Voltage

Connector

Terminal

F102

76

[HO2S2 (bank 1)]

Ground

Coasting from 80 km/h (50 MPH) in D po-
sition (A/T), 4th gear position (M/T)

The voltage should be above 0.68V at 
least once during this procedure.
The voltage should be below 0.18V at least 
once during this procedure.

80

[HO2S2 (bank 2)]

EC-232

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

DTC Logic

INFOID:0000000001734060

DTC DETECTION LOGIC

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the A/F sensors 1. The ECM calcu-
lates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next test.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

1.

Clear the mixture ratio self-learning value. Refer to 

EC-22, "MIXTURE RATIO SELF-LEARNING VALUE

CLEAR : Special Repair Requirement"

.

2.

Start engine.

Is it difficult to start engine?

YES

>> GO TO 3.

NO

>> GO TO 4.

3.

RESTART ENGINE

If it is difficult to start engine, the fuel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.
Does engine start?

YES

>> Go to 

EC-233, "Diagnosis Procedure"

.

NO

>> Check exhaust and intake air leak visually.

4.

PERFORM DTC CONFIRMATION PROCEDURE-II

1.

Keep engine idle for at least 10 minutes.

2.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-233, "Diagnosis Procedure"

.

NO

>> GO TO 5.

Sensor

Input signal to ECM

ECM function

Actuator

A/F sensor 1

Density of oxygen in exhaust gas
(Mixture ratio feedback signal)

Fuel injection control

Fuel injector

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0171

Fuel injection system too 
lean (bank 1)

• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too 

large. (The mixture ratio is too lean.)

• Intake air leaks
• A/F sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection

P0174

Fuel injection system too 
lean (bank 2)