Nissan Frontier D22. Manual - part 269

DTC P0127 IAT SENSOR

EC-179

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EC

DTC P0127 IAT SENSOR

PFP:22630

Component Description

UBS00D3K

The intake air temperature sensor is mounted to the air duct hous-
ing. 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>

*: These data are reference values and are measured between ECM terminal 61
(Intake air temperature sensor) and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

On Board Diagnosis Logic

UBS00D3L

FAIL-SAFE MODE

When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.

SEF329V

Intake air temperature

°C (°F)

Voltage*

V

Resistance

k

Ω

20 (68)

3.5

2.1 - 2.9

80 (176)

1.23 

0.27 - 0.38

SEF012P

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0127

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

Engine operating condition in fail-safe mode

The ECM functions on the assumption that the intake air temperature is 25

°C (77°F).

EC-180

[KA24DE]

DTC P0127 IAT SENSOR

DTC Confirmation Procedure

UBS00D3M

NOTE:
If “DTC Confirmation Procedure” has been previously conducted, always turn ignition switch OFF and wait at
least 5 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).

–

Turn ignition switch ON.

–

Select “DATA MONITOR” mode with CONSULT-II.

–

Check the engine coolant temperature.

–

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).

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-II.

4.

Start engine.

5.

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

6.

If 1st trip DTC is detected, go to 

EC-182, "Diagnostic Procedure"

 .

 WITH GST

Follow the procedure “WITH CONSULT-II”.

PBIB1917E

DTC P0127 IAT SENSOR

EC-181

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Wiring Diagram

UBS00D3N

BBWA0439E

EC-182

[KA24DE]

DTC P0127 IAT SENSOR

Diagnostic Procedure

UBS00D3O

1. 

CHECK POWER SUPPLY

1.

Turn ignition switch OFF.

2.

Disconnect intake air temperature sensor harness connector.

3.

Turn ignition switch ON.

4.

Check voltage between terminal 1 and ground with CONSULT-II
or tester.

OK or NG

OK

>> GO TO 3.

NG

>> GO TO 2.

2. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors E43, M65

●

Harness connectors M81, F36

●

Harness for open or short between ECM and intake air temperature sensor

>> Repair harness or connectors.

3. 

CHECK GROUND CIRCUIT

1.

Turn ignition switch OFF.

2.

Check harness continuity between intake air temperature sensor terminal 2 and engine ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 5.

NG

>> GO TO 4.

SEF329V

Voltage

: Approximately 5V

AEC570A

Continuity should exist.