2008 INFINITI FX35 coolant temperature

EC-204
< SERVICE INFORMATION >[VQ35DE]
DTC P0125 ECT SENSOR
DTC P0125 ECT SENSOR
Component DescriptionINFOID:0000000001326028
NOTE:
If DTC P0125 is displayed with P0117 or P0118, fi
rst perform the trouble diagnosis for DTC P0117 or
P0118. Refer to EC-193
.
The engine coolant temperature (ECT) sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the engine
coolant temperature input. The sens or uses a thermistor which is
sensitive to the change in temperat ure. The electrical resistance of
the thermistor decreases as temperature increases.

*: This data is reference values and is measured between ECM terminal 73 (Engine
coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring in put/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground ot her than ECM terminals, such as the ground.
On Board Diagnosis LogicINFOID:0000000001326029
DTC Confirmation ProcedureINFOID:0000000001326030
CAUTION:
Be careful not to overheat engine.
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-III
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-III.
3. Check that “COOLAN TEMP/S” is above 10 °C (50 °F).
If it is above 10 °C (50 °F), the test result will be OK.
If it is below 10 °C (50 °F), go to following step.
4. Start engine and run it for 65 minutes at idle speed.
SEF594K
Engine coolant
temperature °C ( °F) Voltage* V Resistance k
Ω
-10 (14) 4.4 7.0 - 11.4s 20 (68) 3.5 2.1 - 2.9
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
SEF012P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0125
0125 Insufficient engine cool-
ant temperature for
closed loop fuel control  Voltage sent to ECM from the sensor is not
practical, even when some time has passed
after starting the engine.
 Engine coolant temperature is insufficient for closed loop fuel control.  Harness or connectors
(High resistance in the circuit)
 Engine coolant temperature sensor
Thermostat
3AA93ABC3ACD3AC03ACA3AC03AC63AC53A913A773A893A873A873A8E3A773A983AC73AC93AC03AC3
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DTC P0125 ECT SENSOREC-205
< SERVICE INFORMATION > [VQ35DE]
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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 ProcedureINFOID: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 InspectionINFOID:0000000001326032
ENGINE COOLANT TEMPERATURE SENSOR
PBIB2625E
3AA93ABC3ACD3AC03ACA3AC03AC63AC53A913A773A893A873A873A8E3A773A983AC73AC93AC03AC3
3A893A873A873A8F3A773A9D3AAF3A8A3A8C3A863A9D3AAF3A8B3A8C

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.

If NG, replace engine coolant temperature sensor.
Removal and InstallationINFOID: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
3AA93ABC3ACD3AC03ACA3AC03AC63AC53A913A773A893A873A873A8E3A773A983AC73AC93AC03AC3
3A893A873A873A8F3A773A9D3AAF3A8A3A8C3A863A9D3AAF3A8B3A8C

DTC P0127 IAT SENSOREC-207
< SERVICE INFORMATION > [VQ35DE]
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DTC P0127 IAT SENSOR
Component DescriptionINFOID: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. Electric al resistance of the thermistor
decreases in response to the temperature rise.

*: 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 te rminals, such as the ground.
On Board Diagnosis LogicINFOID:0000000001326035
DTC Confirmation ProcedureINFOID:0000000001326036
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, 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
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EC-210
< SERVICE INFORMATION >[VQ35DE]
DTC P0128 THERMOSTAT FUNCTION
DTC P0128 THERMOSTAT FUNCTION
On Board Diagn
osis LogicINFOID:0000000001326040
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 ProcedureINFOID:0000000001612840
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, 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 en gine 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 EC-210, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001612841
1.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-211, "
Component Inspection".
OK or NG
OK >> GO TO 2.
NG >> Replace engine coolant temperature sensor.
2.CHECK THERMOSTAT
Refer to CO-27, "
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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DTC P0128 THERMOSTAT FUNCTIONEC-211
< SERVICE INFORMATION > [VQ35DE]
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Component InspectionINFOID:0000000001326043
ENGINE COOLANT TEMPERATURE SENSOR
Check resistance between engine cool
ant temperature sensor termi-
nals 1 and 2 as shown in the figure.

If NG, replace engine coolant temperature sensor.
Removal and InstallationINFOID:0000000001326044
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
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DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-275
< SERVICE INFORMATION > [VQ35DE]
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9. Check 1st trip DTC.
10. The 1st trip is detected, go to
EC-279, "
Diagnosis Procedure".
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Disconnect mass air flow sensor harness connector.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness con-
nector.
6. Select Service $03 with GST. Make sure DTC P0102 is detected.
7. Select Service $04 with GST and erase the DTC P0102.
8. Start engine. If it is difficult to start engine, the fuel injection system has a mal-
function.
Perform the following procedure is advised.
a. Crank engine while depressing accelerator pedal.
b. If engine starts, go to EC-279, "
Diagnosis Procedure".
If engine does not start, check exhaust and intake air leak visually.
9. Keep engine at idle for at least 10 minutes.
10. Check 1st trip DTC.
11. If 1st trip DTC is detected, go to EC-279, "
Diagnosis Procedure".
If 1st trip DTC is not detected, per forming the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine and drive the vehicle under the similar condi tions to (1st trip) Freeze Frame Data for 10 min-
utes. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Da ta means the vehicle operation that the following con-
ditions should be satisfied at the same time.
12. Check 1st trip DTC.
13. The 1st trip is detected, go to EC-279, "
Diagnosis Procedure".
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature (T)
condition When the freeze frame data shows lower than 70
°C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
PBIB1565E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature (T)
condition When the freeze frame data shows lower than 70
°C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
3AA93ABC3ACD3AC03ACA3AC03AC63AC53A913A773A893A873A873A8E3A773A983AC73AC93AC03AC3
3A893A873A873A8F3A773A9D3AAF3A8A3A8C3A863A9D3AAF3A8B3A8C

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-285
< SERVICE INFORMATION > [VQ35DE]
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10. The 1st trip is detected, go to
EC-289, "
Diagnosis Procedure".
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness con- nector.
5. Select Service $03 with GST. Make sure DTC P0102 is detected.
6. Select Service $04 with GST and erase the DTC P0102.
7. Start engine. If it is difficult to start engine, the fuel injection system has a mal-
function.
Perform the following procedure is advised.
a. Crank engine while depressing accelerator pedal.
b. If engine starts, go to EC-289, "
Diagnosis Procedure".
If engine does not start, remove ignition plugs and check for fouling, etc.
8. Keep engine at idle for at least 10 minutes.
9. Check 1st trip DTC.
10. If 1st trip DTC is detected, go to EC-289, "
Diagnosis Procedure".
If 1st trip DTC is not detected, per forming the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine and drive the vehicle under the similar condi tions to (1st trip) Freeze Frame Data for 10 min-
utes. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Da ta means the vehicle operation that the following con-
ditions should be satisfied at the same time.
11. Check 1st trip DTC.
12. The 1st trip is detected, go to EC-289, "
Diagnosis Procedure".
Engine coolant temperature (T)
conditionWhen the freeze frame data shows lower than 70
°C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
PBIB1565E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature (T)
condition When the freeze frame data shows lower than 70
°C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
3AA93ABC3ACD3AC03ACA3AC03AC63AC53A913A773A893A873A873A8E3A773A983AC73AC93AC03AC3
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