Infiniti QX56 (Z62). Manual - part 561

EC-222

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0125 ECT SENSOR

P0125 ECT SENSOR

DTC Logic

INFOID:0000000006288280

DTC DETECTION LOGIC

NOTE:
If DTC P0125 is displayed with P0117 or P0118, first perform the trouble diagnosis for DTC P0117,
P0118. Refer to 

EC-217, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.

CHECK ENGINE COOLANT TEMPERATURE SENSOR FUNCTION

 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).

 WITH GST

Follow the procedure “With CONSULT-III” above.
Is the temperature above 10

°

C (50

°

F)?

YES

>> INSPECTION END

NO

>> GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE

 WITH CONSULT-III

1.

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.

CAUTION:

Never overheat engine.

2.

Check 1st trip DTC.

 WITH GST

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected?

YES

>>

EC-222, "Diagnosis Procedure"

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006288281

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-218, "Component Inspection (Engine Coolant Temperature Sensor)"

.

Is the inspection result normal?

YES

>> GO TO 2.

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0125

ECT SENSOR
(Insufficient engine coolant 
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

P0125 ECT SENSOR

EC-223

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NO

>> Replace engine coolant temperature sensor.

2.

CHECK THERMOSTAT OPERATION

When the engine is cold [lower than 70

°

C (158

°

F)] condition, grasp lower radiator hose and confirm that the

engine coolant does not flow.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace thermostat. Refer to 

CO-20, "Removal and Installation"

.

3.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection (Engine Coolant Temperature Sensor)

INFOID:0000000006288610

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect engine coolant temperature sensor harness connector.

3.

Remove engine coolant temperature sensor.

4.

Check resistance between engine coolant temperature sensor
terminals by heating with hot water as shown in the figure.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace engine coolant temperature sensor. Refer to

EM-86, "Exploded View"

.

Terminals

Condition

Resistance (k

Ω

)

1 and 2

Temperature [

°

C (

°

F)]

20 (68)

2.35 - 2.73

50 (122)

0.68 - 1.00

90 (194)

0.236 - 0.260

JMBIA0080ZZ

EC-224

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0127 IAT SENSOR

P0127 IAT SENSOR

DTC Logic

INFOID:0000000006288283

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

 WITH CONSULT-III

1.

Wait until engine coolant temperature is less than 90

°

C (194

°

F)

-

Turn ignition switch ON.

-

Select “DATA MONITOR” mode with CONSULT-III.

-

Check the engine coolant temperature.

-

If the engine coolant temperature is not less than 90

°

C (194

°

F), turn ignition switch OFF and cool down

engine.

NOTE:
Perform the following steps before engine coolant temperature is above 90

°

C (194

°

F).

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-III.

4.

Start engine.

5.

Hold vehicle speed at more than 70 km/h (43 MPH) for 100 consecutive seconds.

CAUTION:

Always drive vehicle at a safe speed.

6.

Check 1st trip DTC.

 WITH GST

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected?

YES

>> Proceed to 

EC-224, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006288284

1.

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-225, "Component Inspection (Intake Air Temperature Sensor)"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Replace mass air flow sensor (with intake air temperature sensor).

2.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0127

IAT SENSOR-B1
(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 intake air temperature sensor 
circuit is open or shorted)

• Intake air temperature sensor

P0127 IAT SENSOR

EC-225

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

>> INSPECTION END

Component Inspection (Intake Air Temperature Sensor)

INFOID:0000000006288285

1.

CHECK INTAKE AIR TEMPERATURE SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect mass air flow sensor harness connector.

3.

Check resistance between mass air flow sensor terminals as per the following.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace mass air flow sensor (with intake air temperature sensor). Refer to 

EM-30, "Removal and

Installation"

.

Terminals

Condition

Resistance (k

Ω

)

1 and 2

Temperature [

°

C (

°

F)]

25 (77)

1.94 - 2.06