Nissan Titan A60. Manual - part 380

EC-186

< DTC/CIRCUIT DIAGNOSIS >

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P0127 IAT SENSOR

P0127 IAT SENSOR

Component Description

INFOID:0000000006158610

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 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

INFOID:0000000006158611

DTC Confirmation Procedure

INFOID:0000000006158612

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next step. 
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich 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.
4. 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.

BBIA0355E

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

P0127 IAT SENSOR

EC-187

< DTC/CIRCUIT DIAGNOSIS >

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• Perform the following steps before engine coolant temperature is above 90

°C (194°F).

5. Turn ignition switch ON.
6. Select “DATA MONITOR” mode with CONSULT-III.
7. Start engine.
8. Hold vehicle speed at more than 70 km/h (43 MPH) for 100 consecutive seconds.
9. Check 1st trip DTC.
10. If 1st trip DTC is detected, go to 

EC-187, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006158613

1.

CHECK GROUND CONNECTIONS

1. Turn ignition switch OFF.

2. Loosen and retighten three ground screws on the body. 

Refer to 

EC-139, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-187, "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-36, "How to Check Terminal"

 and 

GI-39, "Intermittent Incident"

.

For wiring diagram, refer to 

EC-83, "Wiring Diagram"

.

>> INSPECTION END

Component Inspection

INFOID:0000000006158614

INTAKE AIR TEMPERATURE SENSOR

1. Check resistance between intake air temperature sensor termi-

nals 5 and 6 under the following conditions.

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

sensor).

BBIA0354E

Intake air temperature 

°C (°F)]

Resistance (k

Ω)

25 (77)

1.800 - 2.200

BBIA0355E

EC-188

< DTC/CIRCUIT DIAGNOSIS >

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P0127 IAT SENSOR

SEF012P

P0128 THERMOSTAT FUNCTION

EC-189

< DTC/CIRCUIT DIAGNOSIS >

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P0128 THERMOSTAT FUNCTION

On Board Diagnosis Logic

INFOID:0000000006158615

NOTE:

If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308,

first perform the trouble diagnosis for DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307,

P0308. Refer to 

EC-247, "DTC Confirmation Procedure"

.

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

INFOID:0000000006158616

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next step. 
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
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 52°C (126°F).

• Before performing the following procedure, do not fill with the fuel.

1. Turn A/C switch OFF.

2. Turn blower fan switch OFF.

3. Turn ignition switch ON.

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

5. Check the indication of “COOLAN TEMP/S”.

6. If it is below 52

°C (126°F), go to following step.

7. If it is above 52

°C (126°F), cool down the engine to less than 52°C (126°F). Then go to next steps.

8. Start engine and wait at idle for at least 30 minutes.

If “COOLAN TEMP/S” increases to more than 71

°C (160°F) within 30 minutes, turn ignition switch

OFF because the test result will be OK.

9. Check 1st trip DTC.

10. If 1st trip DTC is detected, go to 

EC-189, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006158617

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-190, "Component Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Replace engine coolant temperature sensor.

2.

CHECK THERMOSTAT

Refer to 

CO-23, "Removal and Installation"

.

OK or NG

OK

>> INSPECTION END

NG

>> Replace thermostat.

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 thermostat
• Engine coolant temperature sensor