Infiniti FX35, FX50 (S51). Manual - part 675

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-241

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

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6.

Also check harness for short to power.

Is the inspection result normal?

YES

>> GO TO 4.

NO

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

4.

CHECK FUEL PRESSURE

Check fuel pressure. Refer to 

EC-566, "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-571, "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-571, "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-176, "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.

Check 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-470, "Diagnosis Procedure"

.

7.

CHECK FUEL INJECTOR

1.

Remove fuel injector assembly. Refer to 

EM-40, "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.

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

Clicking sound should be heard.

PBIB3332E

EC-242

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

4.

Disconnect all ignition coil harness connectors.

5.

Prepare pans or saucers under each fuel injector.

6.

Crank engine for approximately 3 seconds.
Check that 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-36, "Intermittent Incident"

.

>> INSPECTION END

P0181 FTT SENSOR

EC-243

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

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P0181 FTT SENSOR

Description

INFOID:0000000005236838

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 terminals 106 (Fuel tank temperature sensor) and 128 (ECM
ground).

DTC Logic

INFOID:0000000005236839

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting 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-244, "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.

4.

PERFORM DTC CONFIRMATION PROCEDURE-II

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

EC-244

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P0181 FTT SENSOR

With CONSULT-III

1.

Cool engine down until “COOLAN TEMP/S” is less than 60

°

C (140

°

F).

2.

Wait at least 10 seconds.

3.

Check 1st trip DTC.

With GST

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected?

YES

>> Go to 

EC-244, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000005236840

1.

CHECK GROUND CONNECTION

1.

Turn ignition switch OFF.

2.

Check ground connection M95. Refer to Ground Inspection in 

GI-39, "Circuit Inspection"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace ground connection.

2.

CHECK DTC WITH “UNIFIED METER AND A/C AMP.”

Refer to 

MWI-45, "CONSULT-III Function (METER/M&A)"

.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Go to 

MWI-61, "Component Function Check"

.

3.

CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect “fuel level sensor unit and fuel pump (main)” harness connector.

3.

Turn ignition switch ON.

4.

Check the voltage between “fuel level sensor unit and fuel pump (main)” harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> GO TO 4.

4.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors M7, B1
• Harness for open or short between ECM and “fuel level sensor unit and fuel pump (main)”

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

5.

CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect “unified meter and A/C amp.” harness connector.

3.

Check the continuity between “fuel level sensor unit and fuel pump (main)” harness connector and “unified
meter and A/C amp.” harness connector.

Fuel level sensor unit and fuel 

pump (main)

Ground

Voltage (V)

Connector

Terminal

B22

4

Ground

Approx. 5