Infiniti M35/M45 Y50. Manual - part 439

 

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Infiniti M35/M45 Y50. Manual - part 439

 

 

DTC P0127 IAT SENSOR

EC-229

[VQ35DE]

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DTC P0127 IAT SENSOR

PFP:22630

Component Description

NBS004VX

The intake air temperature sensor is built-into mass air flow sensor
(1). The sensor detects intake air temperature and transmits a signal
to the ECM.
The temperature sensing unit uses a thermistor which is sensitive to
the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.

<Reference data>

*: This data is reference value and is measured between ECM terminal 34 (Intake air
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 transistor.
Use a ground other than ECM terminals, such as the ground.

On Board Diagnosis Logic

NBS004VY

DTC Confirmation Procedure

NBS004VZ

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.

CAUTION:

Always drive vehicle at a safe speed.
TESTING CONDITION:
This test may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road
test is expected to be easier, it is unnecessary to lift the vehicle.

 WITH CONSULT-II

1.

Wait until engine coolant temperature is less than 90

°

C (194

°

F)

a.

Turn ignition switch ON.

PBIA9559J

Intake air temperature

°

C (

°

F)

Voltage*

V

Resistance

k

25 (77)

3.3

1.800 - 2.200

80 (176)

1.2

0.283 - 0.359

SEF012P

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0127
0127

Intake air temperature 
too high

Rationally incorrect voltage from the sensor is 
sent to ECM, compared with the voltage signal 
from engine coolant temperature sensor.

Harness or connectors
(The sensor circuit is open or shorted)

Intake air temperature sensor

EC-230

[VQ35DE]

DTC P0127 IAT SENSOR

b.

Select “DATA MONITOR” mode with CONSULT-II.

c.

Check the engine coolant temperature.

d.

If the engine coolant temperature is not less than 90

°

C (194

°

F),

turn ignition switch OFF and cool down engine.

Perform the following steps before engine coolant tempera-
ture is above 90

°

C (194

°

F).

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-II.

4.

Start engine.

5.

Hold vehicle speed at more than 70 km/h (43 MPH) for 100 con-
secutive seconds.

6.

If 1st trip DTC is detected, go to 

EC-230, "Diagnostic Procedure"

 .

 WITH GST

Follow the procedure “WITH CONSULT-II” above.

Diagnostic Procedure

NBS004W0

1. 

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten two ground screws on the body.
Refer to 

EC-160, "Ground Inspection"

 .

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2. 

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-231, "Component Inspection"

 .

OK or NG

OK

>> GO TO 3.

NG

>> Replace mass air flow sensor (with intake air temperature sensor).

3. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-153, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

Refer to 

EC-211, "Wiring Diagram"

 .

>> INSPECTION END

SEF189Y

1.

Body ground M70

2.

Body ground M16

PBIB2782E

DTC P0127 IAT SENSOR

EC-231

[VQ35DE]

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Component Inspection

NBS004W1

INTAKE AIR TEMPERATURE SENSOR

1.

Check resistance between mass air flow sensor (1) terminals 5
and 6 under the following conditions.

2.

If NG, replace mass air flow sensor (with intake air temperature
sensor).

Removal and Installation

NBS004W2

MASS AIR FLOW SENSOR

Refer to 

EM-19, "AIR CLEANER AND AIR DUCT"

 .

Intake air temperature 

°

C (

°

F)

Resistance k

25 (77)

1.800 - 2.200

PBIA9559J

SEF012P

EC-232

[VQ35DE]

DTC P0128 THERMOSTAT FUNCTION

DTC P0128 THERMOSTAT FUNCTION

PFP:21200

On Board Diagnosis Logic

NBS004W3

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long
enough.
This is due to a leak in the seal or the thermostat stuck open.

DTC Confirmation Procedure

NBS004W4

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:

For best results, perform at ambient temperature of –10

°

C (14

°

F) or higher.

For best results, perform at engine coolant temperature of –10

°

C (14

°

F) to 60

°

C (140

°

F).

 WITH CONSULT-II

1.

Replace thermostat with new one. Refer to 

CO-29, "WATER INLET AND THERMOSTAT ASSEMBLY"

 .

Use only a genuine NISSAN thermostat as a replacement. If an incorrect thermostat is used, the MIL may
come on.

2.

Turn ignition switch ON.

3.

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

4.

Check that the “COOLAN TEMP/S” is above 60

°

C (140

°

F).

If it is below 60

°

C (140

°

F), go to following step.

If it is above 60

°

C (140

°

F), cool down the engine to less than

60

°

C (140

°

F), then retry from step 1.

5.

Drive vehicle for 10 consecutive minutes under the following
conditions.

If 1st trip DTC is detected, go to 

EC-232, "Diagnostic Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-II” above.

Diagnostic Procedure

NBS004W5

1. 

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-233, "Component Inspection"

 .

OK or NG

OK

>> INSPECTION END

NG

>> Replace engine coolant temperature sensor.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0128
0128

Thermostat function

The engine coolant temperature does not 
reach to specified temperature even though 
the engine has run long enough.

Thermostat

Leakage from sealing portion of thermo-
stat

Engine coolant temperature sensor

VHCL SPEED SE

80 - 120 km/h (50 - 75 MPH)

PBIB1917E

 

 

 

 

 

 

 

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