2008 INFINITI FX35 engine

EC-784
< SERVICE INFORMATION >[VK45DE]
DTC P0122, P0123 TP SENSOR
DTC P0122, P0123 TP SENSOR
Component DescriptionINFOID:0000000001326617
Electric throttle control actuator
consists of throttle control motor,
throttle position sensor, etc. The throttle position sensor responds to
the throttle valve movement.
The throttle position sensor has t he two sensors. These sensors are
a kind of potentiometers which transform the throttle valve position
into output voltage, and emit the voltage signal to the ECM. In addi-
tion, these sensors detect the opening and closing speed of the
throttle valve and feed the voltage signals to the ECM. The ECM
judges the current opening angle of the throttle valve from these sig-
nals and the ECM controls the throttle control motor to make the
throttle valve opening angle properly in response to driving condi-
tion.
CONSULT-III Reference Value in Data Monitor ModeINFOID:0000000001326618
Specification data are reference values.
*: Throttle position sensor 2 signal is converted by ECM internally. Thus, it differs from ECM terminal voltage signal.
On Board Diagn osis LogicINFOID:0000000001326619
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.
DTC Confirmation ProcedureINFOID:0000000001326620
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:
Before performing the following procedure, confirm that battery voltage is more than 8V at idle.
1. Start engine and let it idle for 1 second.
2. Check DTC.
3. If DTC is detected, go to EC-786, "
Diagnosis Procedure".
PBIB0145E
MONITOR ITEM CONDITION SPECIFICATION
TP SEN 1-B1
TP SEN 2-B1*  Ignition switch: ON
(Engine stopped)
 Selector lever: D Accelerator pedal: Fully released More than 0.36V
Accelerator pedal: Fully depressed Less than 4.75V
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0122
0122 Throttle position sensor
2 circuit low input An excessively low voltage from the TP sensor
2 is sent to ECM.  Harness or connectors
(TP sensor 2 circuit is open or shorted.)
(APP sensor 2 circuit is shorted.)
 Electric throttle control actuator (TP sensor 2)
 Accelerator pedal position sensor (APP sensor 2)
P0123
0123
Throttle position sensor
2 circuit high input An excessively high voltage from the TP sensor
2 is sent to ECM.
Engine operation condition in fail-safe mode
The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor.
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EC-786
< SERVICE INFORMATION >[VK45DE]
DTC P0122, P0123 TP SENSOR
Diagnosis Procedure
INFOID:0000000001326622
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-723, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK THROTTLE POSITION SE NSOR 2 POWER SUPPLY CIRCUIT-I
TER-
MI-
NAL
NO. WIRE
COLOR ITEM CONDITION DATA (DC Voltage)
47 L Sensor power supply (Throt-
tle position sensor) [Ignition switch: ON]
Approximately 5V
50 W Throttle position sensor 1 [Ignition switch: ON]
 Engine stopped
 Selector lever: D
 Accelerator pedal: Fully released
More than 0.36V
[Ignition switch: ON]
 Engine stopped
 Selector lever: D
 Accelerator pedal: Fully depressed Less than 4.75V
66 B Sensor ground
(Throttle position sensor) [Engine is running]

Warm-up condition
 Idle speed Approximately 0V
69 R Throttle position sensor 2 [Ignition switch: ON]
 Engine stopped
 Selector lever: D
 Accelerator pedal: Fully released
Less than 4.75V
[Ignition switch: ON]
 Engine stopped
 Selector lever: D
 Accelerator pedal: Fully depressed More than 0.36V
91 G Sensor power supply
(APP sensor 2) [Ignition switch: ON]
Approximately 5V
PBIB2195E
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EC-790
< SERVICE INFORMATION >[VK45DE]
DTC P0125 ECT SENSOR
DTC P0125 ECT SENSOR
Component DescriptionINFOID:0000000001326625
NOTE:
If DTC P0125 is displayed with P0117 or P0118, fi
rst perform the trouble diagnosis for DTC P0117 or
P0118. Refer to EC-779
.
The engine coolant temperature sens or 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 sensor uses a thermistor which is sensitive to
the change in temperature. The elec trical resistance of the ther-
mistor decreases as temperature increases.

*: These data are reference values and are 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:0000000001326626
DTC Confirmation ProcedureINFOID:0000000001326627
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.
SEF594K
Engine coolant
temperature °C ( °F) Voltage* V Resistance k
Ω
–10 (14) 4.4 7.0 - 11.4 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
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DTC P0125 ECT SENSOREC-791
< SERVICE INFORMATION > [VK45DE]
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4. Start engine and run it for 65 minutes at idle speed.
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-791, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001326628
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-723, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-791, "
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-52
.
4.CHECK INTERMITTENT INCIDENT
Refer to EC-717
.
Refer to EC-781, "
Wiring Diagram".
>> INSPECTION END
Component InspectionINFOID:0000000001326629
ENGINE COOLANT TEMPERATURE SENSOR
PBIB2195E
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EC-792
< SERVICE INFORMATION >[VK45DE]
DTC P0125 ECT SENSOR
1. Check resistance between engine coolant temperature sensor
terminals 1 and 2 as shown in the figure.

2. If NG, replace engine coolant temperature sensor.
Removal and InstallationINFOID:0000000001326630
ENGINE COOLANT TEMPERATURE SENSOR
Refer to CO-52.
PBIB2005E
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 P0127 IAT SENSOREC-793
< SERVICE INFORMATION > [VK45DE]
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DTC P0127 IAT SENSOR
Component DescriptionINFOID: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. Electric al resistance of the thermistor
decreases in response to the temperature rise.

*: 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 te rminals, such as the ground.
On Board Diagnosis LogicINFOID:0000000001326632
DTC Confirmation ProcedureINFOID:0000000001326633
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).
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
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EC-796
< SERVICE INFORMATION >[VK45DE]
DTC P0128 THERMOSTAT FUNCTION
DTC P0128 THERMOSTAT FUNCTION
On Board Diagn
osis LogicINFOID: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 ProcedureINFOID:0000000001326638
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-796, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001326639
1.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-797, "
Component Inspection".
OK or NG
OK >> GO TO 2.
NG >> Replace engine coolant temperature sensor.
2.CHECK THERMOSTST
Refer to 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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DTC P0128 THERMOSTAT FUNCTIONEC-797
< SERVICE INFORMATION > [VK45DE]
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Component InspectionINFOID:0000000001326640
ENGINE COOLANT TEMPERATURE SENSOR
1. Check resistance between engine
coolant temperature sensor
terminals 1 and 2 as shown in the figure.

2. If NG, replace engine coolant temperature sensor.
Removal and InstallationINFOID:0000000001326641
ENGINE COOLANT TEMPERATURE SENSOR
Refer to CO-52.
PBIB2005E
Temperature °C ( °F) Resistance k Ω
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.0
90 (194) 0.236 - 0.260
SEF012P
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