2009 NISSAN LATIO engine coolant

EC-684< SERVICE INFOMATION >
[MR TYPE 1]
DTC P0125 ECT SENSOR
DTC P0125 ECT SENSOR
Description INFOID:0000000004537151
NOTE:
If DTC P0125 is displayed with P0117 or P0118, fi rst perform the trouble diagnosis for DTC P0117 or
P0118. Refer to EC-674 .
COMPONENT DESCRIPTION
The engine coolant temperature 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 sensor uses a thermistor which is sensitive to
the change in temperature. The elec trical resistance of the ther-
mistor decreases as temperature increases.

*: This data is reference values and is measured between ECM terminal 38 (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 Diagn osis Logic INFOID:0000000004537152
This self-diagnosis ha one trip detection logic.
DTC Confirmation Procedure INFOID:0000000004537153
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). 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

DTC P0125 ECT SENSOR
EC-685
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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. 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 DTC.
6. If DTC is detected, go to EC-685, " Diagnosis Procedure " .
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis Procedure INFOID:00000000045371541.
CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground screw on the body.
Refer to EC-632, " Ground Inspection " .
OK or NG OK >> GO TO 2.
NG >> Repair or replace ground connections. 2.
CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-686, " 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-45 .
4.
CHECK INTERMITTENT INCIDENT
Refer to EC-626 .
Refer to EC-676, " Wiring Diagram " .
>> INSPECTION END :
Vehicle front
1. Body ground E24 2. Engine ground F9 3. Engine ground F16
4. Body ground E15 BBIA0698E

EC-686< SERVICE INFOMATION >
[MR TYPE 1]
DTC P0125 ECT SENSOR
Component Inspection INFOID:0000000004537155
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 Installation INFOID:0000000004537156
ENGINE COOLANT TEMPERATURE SENSOR
Refer to EM-186 . 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

DTC P0127 IAT SENSOR
EC-687
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DTC P0127 IAT SENSOR
Component Description INFOID:0000000004537157
The intake air temperature sensor is built into mass air flow sensor
(1). 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 value and is measured between ECM terminal 46 (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 Logic INFOID:0000000004537158
DTC Confirmation Procedure INFOID:0000000004537159
CAUTION:
Always drive vehicle at a safe speed.
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:
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). PBIA9559J
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
(Intake temperature sensor circuit is open
or shorted)
• Intake air temperature sensor

DTC Confirmation Proce-
dure " .
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:0000000004537164
WITH CONSULT-III
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 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”. If it is below 52 °C (126 °F), go to following step.
If it is above 52 °C (126 °F), cool down the engine to less than 52 °C (126 °F). Then go to next steps.
6. 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.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to EC-690, " Diagnosis Procedure " .
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis Procedure INFOID:0000000004537165Component Inspection " .
OK or NG OK >> GO TO 2.
NG >> Replace engine coolant temperature sensor. 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

DTC P0128 THERMOSTAT FUNCTION
EC-691
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Component Inspection
INFOID:0000000004537166
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 Installation INFOID:0000000004537167
ENGINE COOLANT TEMPERATURE SENSOR Refer to EM-186 . 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

DTC P0171 FUEL INJECT
ION SYSTEM FUNCTION
EC-741
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7. If it is difficult to start engine at step 6,
the fuel injection system has a malfunction, too.
8. Crank engine while depressing accelerator pedal. If engine starts, go to EC-743, " Diagnosis Procedure " . If
engine does not start, c heck exhaust and intake air leak visually.
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 (1) harness connector.
4. Restart engine and let idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor (1) harness connector.
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 again and let it idle for at least 10 minutes.
9. Select Service $07 with GST. The 1st trip DTC P0171 should be
detected at this stage, if a malfunction exists. If so, go to EC-743, " Diagnosis Procedure " .
NOTE:
If 1st trip DTC is not detected during above proc edure, performing 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.
10. If it is difficult to start engine at step 8, the fuel injection system has a malfunction.
11. Crank engine while depressing accelerator pedal. If engine starts, go to EC-743, " Diagnosis Procedure " .
If engine does not start, check exhaust and intake air leak visually.
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). BBIA0701E
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).

" Diagnosis Procedure " .
NOTE:
If 1st trip DTC is not detected during above proc edure, performing 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 conditions 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.
7. If it is difficult to start engine at step 6, the fuel injection system has a malfunction, too.
Sensor Input Signal to ECM ECM function Actuator
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
(Mixture ratio feedback signal) Fuel injection control Fuel injectorDTC No.
Trouble diagnosis
name DTC detecting condition Possible cause
P0172
0172 Fuel injection system
too rich • Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too large. (The mixture ratio is too rich.) • Air fuel ratio (A/F) sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Mass air flow sensor 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).