2008 NISSAN LATIO engine coolant

EC-156
< SERVICE INFORMATION >
DTC P0037, P0038 HO2S2 HEATER
DTC P0037, P0038 HO2S2 HEATER
DescriptionINFOID:0000000001702632
SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.
OPERATION
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000001702633
Specification data are reference values.
On Board Diagnosis LogicINFOID:0000000001702634
DTC Confirmation ProcedureINFOID:0000000001702635
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:
Before performing the following procedure, confirm that battery voltage is between 10.5V and 16V at
idle.
WITH CONSULT-II
Sensor Input Signal to ECM ECM Function Actuator
Camshaft position sensor (PHASE)
Engine speed
Heated oxygen sensor 2
heater controlHeated oxygen sensor 2 heater Crankshaft position sensor (POS)
Engine coolant temperature sensorEngine coolant tempera-
ture
Mass air flow sensor Amount of intake air
Engine speed rpm Heated oxygen sensor 2 heater
Above 3,600OFF
• Below 3,600 rpm after the following conditions are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1
minute and at idle for 1 minute under no loadON
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 HTR (B1)• Engine speed: Below 3,600 rpm after the following conditions are met
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load.ON
• Engine speed: Above 3,600 rpm OFF
DTC No.Trouble diagnosis
nameDTC detecting condition Possible cause
P0037
0037Heated oxygen
sensor 2 heater
control circuit lowThe current amperage in the heated oxygen sensor
2 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the heated oxygen sensor 2 heater.)• Harness or connectors
(Heated oxygen sensor 2 heater circuit is
open or shorted.)
• Heated oxygen sensor 2 heater
P0038
0038Heated oxygen
sensor 2 heater
control circuit highThe current amperage in the heated oxygen sensor
2 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the heated oxygen sensor 2 heater.)• Harness or connectors
(Heated oxygen sensor 2 heater circuit is
shorted.)
• Heated oxygen sensor 2 heater

DTC P0117, P0118 ECT SENSOR
EC-187
< SERVICE INFORMATION >
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DTC P0117, P0118 ECT SENSOR
Component DescriptionINFOID:0000000001702672
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 electrical resistance of the ther-
mistor decreases as temperature increases.

*: This data is reference value and is measured between ECM terminal 38 (Engine
coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicINFOID:0000000001702673
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
SEF594K
Engine coolant temperature
°C (°F)Voltage* V Resistance kΩ
–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
NameDTC Detecting Condition Possible Cause
P0117
0117Engine coolant tem-
perature sensor cir-
cuit low inputAn excessively low voltage from the sensor is
sent to ECM.• Harness or connectors
(Engine coolant temperature sensor circuit is
open or shorted.)
• Engine coolant temperature sensor P0118
0118Engine coolant tem-
perature sensor cir-
cuit high inputAn excessively high voltage from the sensor is
sent to ECM.

EC-188
< SERVICE INFORMATION >
DTC P0117, P0118 ECT SENSOR
DTC Confirmation Procedure
INFOID:0000000001702674
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.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Wait at least 5 seconds.
4. If DTC is detected, go to EC-189, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Detected items Engine operating condition in fail-safe mode
Engine coolant temper-
ature sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch ON
or START.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided
(CONSULT-II display)
Just as ignition switch is turned ON or START 40°C (104°F)
More than approx. 4 minutes after ignition ON or START 80°C (176°F)
Except as shown above40 - 80°C (104 - 176°F)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates while
engine is running.
SEF058Y

EC-190
< SERVICE INFORMATION >
DTC P0117, P0118 ECT SENSOR
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK ECT SENSOR POWER SUPPLY CIRCUIT
1. Disconnect engine coolant temperature (ECT) sensor (1) har-
ness connector.
- : Vehicle front
2. Turn ignition switch ON.
3. Check voltage between ECT sensor terminal 1 and ground with
CONSULT-II or tester.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power
in harness or connectors.
3.CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 44 and ECT sensor terminal 2.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK ENGINE COOLANT TEMPERATURE SENSOR
:Vehicle front
1. Body ground E24 2. Engine ground F9 3. Engine ground F16
4. Body ground E15
BBIA0698E
PBIB3324E
Voltage: Approximately 5V
PBIB0080E
Continuity should exist.

DTC P0117, P0118 ECT SENSOR
EC-191
< SERVICE INFORMATION >
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Refer to EC-191, "Component Inspection".
OK or NG
OK >> GO TO 5.
NG >> Replace engine coolant temperature sensor.
5.CHECK INTERMITTENT INCIDENT
Refer to EC-136
.
>>INSPECTION END
Component InspectionINFOID:0000000001702677
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:0000000001702678
ENGINE COOLANT TEMPERATURE SENSOR
Refer to EM-62.
PBIB2005E
Temperature°C (°F) Resistance kΩ
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
SEF012P

EC-198
< SERVICE INFORMATION >
DTC P0125 ECT SENSOR
DTC P0125 ECT SENSOR
DescriptionINFOID:0000000001702687
NOTE:
If DTC P0125 is displayed with P0117 or P0118, first perform the trouble diagnosis for DTC P0117 or
P0118. Refer to EC-187
.
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 electrical 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 input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicINFOID:0000000001702688
This self-diagnosis ha one trip detection logic.
DTC Confirmation ProcedureINFOID:0000000001702689
CAUTION:
Be careful not to overheat engine.
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.
WITH CONSULT-II
1. Turn ignition switch ON.
SEF594K
Engine coolant
temperature°C (°F)Voltage* V Resistance kΩ
−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
0125Insufficient 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-199
< SERVICE INFORMATION >
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2. Select “DATA MONITOR” mode with CONSULT-II.
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.
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. If DTC is detected, go to EC-199, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Diagnosis ProcedureINFOID:0000000001702690
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground screw on the body.
Refer to EC-142, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-200, "
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-17
.
4.CHECK INTERMITTENT INCIDENT
Refer to EC-136
.
Refer to EC-189, "
Wiring Diagram".
SEF058Y
:Vehicle front
1. Body ground E24 2. Engine ground F9 3. Engine ground F16
4. Body ground E15
BBIA0698E

EC-200
< SERVICE INFORMATION >
DTC P0125 ECT SENSOR
>>INSPECTION END
Component InspectionINFOID:0000000001702691
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:0000000001702692
ENGINE COOLANT TEMPERATURE SENSOR
Refer to CO-17.
PBIB2005E
Engine coolant temperature°C (°F) Resistance kΩ
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
SEF012P