Nissan Frontier D40. Manual - part 475

P0125 ECT SENSOR

EC-591

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

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F

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EC

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1.

Turn ignition switch ON.

2.

Select “DATA MONITOR” mode with CONSULT-III.

3.

Check that “COOLAN TEMP/S” is above 20

°

C (68

°

F).

If the temperature is above 20

°

C (68

°

F), the test result will be OK.

If the temperature is below 20

°

C (68

°

F), go to following step.

4.

Start engine and run it for 65 minutes at idle speed.
If “COOLAN TEMP/S” increases to more than 20

°

C (68

°

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-591, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000005273559

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

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

EC-549, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-591, "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 that the

engine coolant does not flow.

OK or NG

OK

>> GO TO 4.

NG

>> Repair or replace thermostat. Refer to 

CO-54, "Removal and Installation"

.

4.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-46, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000005273560

ENGINE COOLANT TEMPERATURE SENSOR

BBIA0539E

EC-592

< COMPONENT DIAGNOSIS >

[VQ40DE]

P0125 ECT SENSOR

1.

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

<Reference data>

2.

If NG, replace engine coolant temperature sensor.

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

P0127 IAT SENSOR

EC-593

< COMPONENT DIAGNOSIS >

[VQ40DE]

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P0127 IAT SENSOR

Component Description

INFOID:0000000005273561

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:

Never 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:0000000005273562

DTC Confirmation Procedure

INFOID:0000000005273563

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
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.

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 96

°

C (205

°

F)

a.

Turn ignition switch ON.

b.

Select “DATA MONITOR” mode with CONSULT-III.

c.

Check the engine coolant temperature.

PBIA9559J

Intake air temperature

°

C (

°

F)

Voltage*

V

Resistance

k

Ω

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-594

< COMPONENT DIAGNOSIS >

[VQ40DE]

P0127 IAT SENSOR

d.

If the engine coolant temperature is not less than 96

°

C (205

°

F), turn ignition switch OFF and cool down

engine.
• Perform the following steps before engine coolant temperature is above 96

°

C (205

°

F).

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-III.

4.

Start engine.

5.

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

6.

Check 1st trip DTC.

7.

If 1st trip DTC is detected, go to 

EC-594, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000005273564

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

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

EC-549, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-594, "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 

GI-46, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000005273565

INTAKE AIR TEMPERATURE SENSOR

1.

Check resistance between intake air temperature sensor (1) ter-
minals 5 and 6 under the following conditions.

2.

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

BBIA0539E

Intake air temperature 

°

C (

°

F)

Resistance k

Ω

25 (77)

1.800 - 2.200

PBIA9559J