Infiniti FX35 / FX45. Manual - part 361

DTC P0125 ECT SENSOR

EC-205

< SERVICE INFORMATION >

[VQ35DE]

C

D

E

F

G

H

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J

K

L

M

A

EC

N

P

O

If “COOLAN TEMP/S” increases to more than 10

°

C (50

°

F) within 65 minutes, stop engine because

the test result will be OK.

5.

Check 1st trip DTC.

6.

If 1st trip DTC is detected, go to 

EC-205, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000001326031

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten ground screw on the body. Refer to 

EC-144, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-205, "Component Inspection"

.

OK or NG

OK

>> GO TO 3.

NG

>> Replace engine coolant temperature sensor.

3.

CHECK THERMOSTAT OPERATION

When the engine is cold [lower than 70

°

C (158

°

F)] condition, grasp lower radiator hose and confirm the engine

coolant does not flow.
OK or NG

OK

>> GO TO 4.

NG

>> Repair or replace thermostat. Refer to 

CO-27

.

4.

CHECK INTERMITTENT INCIDENT

Refer to 

EC-139

.

Refer to 

EC-195, "Wiring Diagram"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001326032

ENGINE COOLANT TEMPERATURE SENSOR

PBIB2625E

EC-206

< SERVICE INFORMATION >

[VQ35DE]

DTC P0125 ECT SENSOR

Check resistance between engine coolant temperature sensor termi-
nals 1 and 2 as shown in the figure.

<Reference data>

If NG, replace engine coolant temperature sensor.

Removal and Installation

INFOID:0000000001326033

ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

CO-27

.

PBIB2005E

Engine coolant temperature

°

C (

°

F)

Resistance

k

Ω

20 (68)

2.1 - 2.9

50 (122)

0.68 - 1.00

90 (194)

0.236 - 0.260

SEF012P

DTC P0127 IAT SENSOR

EC-207

< SERVICE INFORMATION >

[VQ35DE]

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DTC P0127 IAT SENSOR

Component Description

INFOID:0000000001326034

The intake air temperature sensor is built into mass air flow sensor.
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 values 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

INFOID:0000000001326035

DTC Confirmation Procedure

INFOID:0000000001326036

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-III

1.

Wait until engine coolant temperature is less than 90

°

C (194

°

F)

a.

Turn ignition switch ON.

b.

Select “DATA MONITOR” mode with CONSULT-III.

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 temperature is above 90

°

C (194

°

F).

PBIB1604E

Intake air temperature

°

C (

°

F)

Voltage*

V

Resistance

k

Ω

25 (77)

3.30

1.800 - 2.200

80 (176)

1.22

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

(Intake air temperature sensor circuit is 
open or shorted)

• Intake air temperature sensor

EC-208

< SERVICE INFORMATION >

[VQ35DE]

DTC P0127 IAT SENSOR

2.

Start engine.

3.

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

4.

Check 1st trip DTC.

5.

If 1st trip DTC is detected, go to 

EC-208, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000001326037

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten ground screw on the body. Refer to 

EC-144, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-208, "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-139

.

Refer to 

EC-190, "Wiring Diagram"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001326038

INTAKE AIR TEMPERATURE SENSOR

Check resistance between intake air temperature sensor terminals 5
and 6 under the following conditions.

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

PBIB2625E

Intake air temperature 

°

C (

°

F)

Resistance k

Ω

25 (77)

1.800 - 2.200

PBIB1604E