Infiniti G37 Coupe. Manual - part 514

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-237

< COMPONENT DIAGNOSIS >

[VQ37VHR]

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EC

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3.

Turn ignition switch OFF and wait at least 10 seconds.

4.

Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for 10 min-
utes. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.

5.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-237, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001734063

1.

CHECK EXHAUST GAS LEAK

1.

Start engine and run it at idle.

2.

Listen for an exhaust gas leak before three way catalyst 1.

Is exhaust gas leak detected?

YES

>> Repair or replace.

NO

>> GO TO 2.

2.

CHECK FOR INTAKE AIR LEAK

Listen for an intake air leak after the mass air flow sensor.

Is intake air leak detected?

YES

>> Repair or replace.

NO

>> GO TO 3.

3.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect corresponding A/F sensor 1 harness connector.

3.

Disconnect ECM harness connector.

4.

Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

Engine speed

Engine speed in the freeze frame data 

±

 400 rpm

Vehicle speed

Vehicle speed in the freeze frame data 

±

 10 km/h (6 MPH)

Engine coolant temperature (T) condition

When the freeze frame data shows lower than 70 

°

C (158 

°

F),

T should be lower than 70 

°

C (158 

°

F).

When the freeze frame data shows higher than or equal to 70 

°

C (158 

°

F),

T should be higher than or equal to 70 

°

C (158 

°

F).

PBIB1922E

DTC

A/F sensor 1

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0172

1

F3

1

F102

57

Existed

2

61

P0175

2

F20

1

65

2

66

EC-238

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

5.

Check the continuity between A/F sensor 1 harness connector or ECM harness connector and ground.

6.

Also check harness for short to power.

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 FUEL PRESSURE

1.

Release fuel pressure to zero. Refer to 

EC-601, "Inspection"

.

2.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-601, "Inspection"

.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> Replace “fuel filter and fuel pump assembly”.

5.

CHECK MASS AIR FLOW SENSOR

With CONSULT-III

1.

Install all removed parts.

2.

Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-III.
For specification, refer to 

EC-606, "Mass Air Flow Sensor"

.

With GST

1.

Install all removed parts.

2.

Check mass air flow sensor signal in “Service $01” with GST.
For specification, refer to 

EC-606, "Mass Air Flow Sensor"

.

Is the measurement value within the specification?

YES

>> GO TO 6.

NO

>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or

grounds. Refer to 

EC-173, "Diagnosis Procedure"

.

6.

CHECK FUNCTION OF FUEL INJECTOR

With CONSULT-III

1.

Start engine.

2.

Perform “POWER BALANCE” in “ACTIVE TEST” mode with CONSULT-III.

3.

Make sure that each circuit produces a momentary engine speed drop.

Without CONSULT-III

1.

Start engine and let it idle.

2.

Listen to each fuel injector operating sound.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

EC-487, "Diagnosis Procedure"

.

7.

CHECK FUELINJECTOR

DTC

A/F sensor 1

ECM

Ground

Continuity

Bank

Connector

Terminal

Connector

Terminal

P0172

1

F3

1

F102

57

Ground

Not existed

2

61

P0175

2

F20

1

65

2

66

At idling: Approximately 350 kPa (3.57 kg/cm

2

, 51 psi)

Clicking sound should be heard.

PBIB3332E

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-239

< COMPONENT DIAGNOSIS >

[VQ37VHR]

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1.

Remove fuel injector assembly. Refer to 

EM-36, "Removal and Installation"

.

Keep fuel hose and all fuel injectors connected to fuel tube.

2.

Confirm that the engine is cooled down and there are no fire hazards near the vehicle.

3.

Disconnect all fuel injector harness connectors.

4.

Disconnect all ignition coil harness connectors.

5.

Prepare pans or saucers under each fuel injectors.

6.

Crank engine for about 3 seconds.
Make sure fuel does not drip from fuel injector.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Replace the fuel injectors from which fuel is dripping. Always replace O-ring with new one. 

8.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

EC-240

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0181 FTT SENSOR

P0181 FTT SENSOR

Description

INFOID:0000000001734064

The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.
<Reference data>

*: These data are reference values and are measured between ECM terminal 106 (Fuel tank temperature sensor) and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM’s transis-
tor. Use a ground other than ECM terminals, such as the ground.

DTC Logic

INFOID:0000000001734065

DTC 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.

Turn ignition switch ON and wait at least 10 seconds.

2.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-241, "Diagnosis Procedure"

.

NO

>> GO TO 3.

3.

CHECK ENGINE COOLANT TEMPERATURE

With CONSULT-III

1.

Select “COOLAN TEMP/S” in “DATA MONITOR” with CONSULT-III.

2.

Check “COOLAN TEMP/S” value.

With GST

Follow the procedure “With CONSULT-III” above.

“COOLAN TEMP/S” less than 60

°

C (140

°

F)?

YES

>> INSPECTION END

NO

>> GO TO 4.

Fluid temperature 

°

C (

°

F)

Voltage* V

Resistance k

Ω

20 (68)

3.5

2.3 - 2.7

50 (122)

2.2

0.79 - 0.90

SEF012P

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0181

Fuel tank temperature 
sensor circuit range/per-
formance

Rationally incorrect voltage from the sensor is 
sent to ECM, compared with the voltage signals 
from engine coolant temperature sensor and in-
take air temperature sensor.

• Harness or connectors

(The sensor circuit is open or shorted)

• Fuel tank temperature sensor