Infiniti FX35 / FX45. Manual — part 508
DTC P0127 IAT SENSOR
EC-793
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DTC P0127 IAT SENSOR
Component Description
INFOID:0000000001326631
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>
*: These data are reference values and are 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:0000000001326632
DTC Confirmation Procedure
INFOID:0000000001326633
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).
2.
Start engine.
PBIB1604E
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-794
< SERVICE INFORMATION >
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DTC P0127 IAT SENSOR
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
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis Procedure
INFOID:0000000001326634
1.
CHECK GROUND CONNECTIONS
1.
Turn ignition switch OFF.
2.
Loosen and retighten three ground screws on the body.
Refer to
OK or NG
OK
>> GO TO 2.
NG
>> Repair or replace ground connections.
2.
CHECK INTAKE AIR TEMPERATURE SENSOR
EC-778, "Component Inspection"
OK or NG
OK
>> GO TO 3.
NG
>> Replace mass air flow sensor (with intake air temperature sensor).
3.
CHECK INTERMITTENT INCIDENT
>> INSPECTION END
Component Inspection
INFOID:0000000001326635
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).
PBIB2195E
Intake air temperature
°
C (
°
F)
Resistance k
Ω
25 (77)
1.800 - 2.200
PBIB1604E
DTC P0127 IAT SENSOR
EC-795
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Removal and Installation
INFOID:0000000001326636
MASS AIR FLOW SENSOR
.
SEF012P
EC-796
< SERVICE INFORMATION >
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DTC P0128 THERMOSTAT FUNCTION
DTC P0128 THERMOSTAT FUNCTION
On Board Diagnosis Logic
INFOID:0000000001326637
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:0000000001326638
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 71
°
C (160
°
F).
• Before performing the following procedure, do not fill with the fuel.
WITH CONSULT-III
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”.
If it is below 71
°
C (160
°
F), go to following step.
If it is above 71
°
C (160
°
F), cool down the engine to less than 71
°
C (160
°
F), then go to next step.
6.
Start engine.
7.
Wait at idle for a 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.
8.
Check 1st trip DTC.
9.
If 1st trip DTC is detected, go to
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis Procedure
INFOID:0000000001326639
1.
CHECK ENGINE COOLANT TEMPERATURE SENSOR
EC-797, "Component Inspection"
OK or NG
OK
>> GO TO 2.
NG
>> Replace engine coolant temperature sensor.
2.
CHECK THERMOSTST
CO-53, "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 en-
gine has run long enough.
• Thermostat
• Leakage from sealing portion of thermo-
stat
• Engine coolant temperature sensor
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