Nissan Pathfinder. Manual - part 477

EC-214

< DTC/CIRCUIT DIAGNOSIS >

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P0128 THERMOSTAT FUNCTION

P0128 THERMOSTAT FUNCTION

DTC Logic

INFOID:0000000009178144

DTC DETECTION LOGIC

NOTE:

If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305 or P0306, first perform

the trouble diagnosis for P0300, P0301, P0302, P0303, P0304, P0305, and P0306. Refer to 

EC-274, "DTC

Logic"

.

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 being stuck open.

DTC CONFIRMATION PROCEDURE

NOTE:

Never refuel before and during the following procedure.

1.

PRECONDITIONING-I

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next test.

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.

PRECONDITIONING-II

With CONSULT

1. Turn ignition switch ON.

2. Check the following conditions:

3. Select “DATA MONITOR” mode of “ENGINE” using CONSULT.

4. Check the following conditions:

Is the condition satisfied?

YES

>> GO TO 3.

NO

>> 1. Satisfy the condition.

2. GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE-I

With CONSULT

1. Start engine.

2. Drive the vehicle until the following condition is satisfied.

CAUTION:

Always drive vehicle at safe speed.

-

STEP 1

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0128

THERMSTAT FNCTN
[Coolant thermostat (coolant 
temperature below thermostat 
regulating temperature)]

The engine coolant temperature does not 
reach to specified temperature even though 
the engine has run long enough.

• Thermostat
• Leakage from sealing portion of ther-

mostat

• Engine coolant temperature sensor

Ambient temperature

−10°C (14°F) or more

A/C switch

OFF

Blower fan switch

OFF

COOLANT TEMP/S

−10°C – 55°C (14 – 131°F)

P0128 THERMOSTAT FUNCTION

EC-215

< DTC/CIRCUIT DIAGNOSIS >

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Drive the vehicle under the conditions instructed below until the difference between “COOLANT TEMP/S”

and “FUEL T/TMP SE” becomes at least 25

°C (45°F).

*: Example

-

STEP 2

Drive the vehicle at 50 km/h (32 MPH) or more with the difference between “COOLANT TEMP/S” and “FUEL

T/TMP SE” maintained at 25

°C (45°F) or more.

NOTE:

Keep the accelerator pedal as steady as possible during cruising.

-

STEP 3

Drive the vehicle at 50 km/h (32 MPH) or more until “COOLANT TEMP/S” increases by 6

°C (43°F).

NOTE:

Keep the accelerator pedal as steady as possible during cruising.

Is the condition satisfied?

YES

>> GO TO 4.

NO

>> GO TO 1.

4.

PERFORM DTC CONFIRMATION PROCEDURE-II

With CONSULT

1. Drive the vehicle until the following condition is satisfied.

CAUTION:

Always drive vehicle at safe speed.

2. Check 1st trip DTC.
Is 1st trip DTC detected?

YES

>> Proceed to 

EC-215, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000009178145

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Check engine coolant temperature sensor. Refer to 

EC-215, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Replace engine coolant temperature sensor.

2.

CHECK THERMOSTAT

Check thermostat. Refer to 

CO-24, "Removal and Installation"

.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace thermostat. Refer to 

CO-24, "Removal and Installation"

.

Component Inspection

INFOID:0000000009178146

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

COOLANT TEMP/S

74

°C (165°F) or less

FUEL T/TMP SE

Less than the value calculated by sub-
tracting 25

°C (45°F) from “COOLANT 

TEMP/S”.*

COOLANT TEMP/S

FUEL T/TMP SE

70

°C (158°F)

45

°C (113°F) or less

65

°C (149°F)

40

°C (104°F) or less

60

°C (140°F)

35

°C (95°F) or less

COOLANT TEMP/S

71

°C (160°F) or more

EC-216

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

P0128 THERMOSTAT FUNCTION

1. Turn ignition switch OFF.

2. Disconnect engine coolant temperature sensor harness connector.

3. Remove engine coolant temperature sensor. Refer to 

CO-26, "Removal and Installation"

.

4. Check resistance between engine coolant temperature sensor

terminals as per the following.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace engine coolant temperature sensor. Refer to 

CO-26, "Removal and Installation"

.

ECT sensor

Condition

Resistance 

(k

Ω)

+

−

Terminal

1

2

Temperature [

°C (°F)]

20 (68)

2.37 - 2.63

50 (122)

0.68 - 1.00

90 (194)

0.236 - 0.260

JMBIA0080ZZ

P0130, P0150 A/F SENSOR 1

EC-217

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P0130, P0150 A/F SENSOR 1

DTC Logic

INFOID:0000000009178147

DTC DETECTION LOGIC

To judge malfunctions, the diagnosis checks that the A/F signal computed by ECM from the A/F sensor 1 sig-

nal fluctuates according to fuel feedback control.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next test.

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:

Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A

1. Start engine and warm it up to normal operating temperature.

2. Let engine idle for 2 minutes.

3. Check 1st trip DTC.
Is 1st trip DTC detected?

YES

>> Proceed to 

EC-219, "Diagnosis Procedure"

.

NO-1 >> With CONSULT: GO TO 3.

NO-2 >> With GST: GO TO 7.

3.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 FUNCTION

1. Start engine and warm it up to normal operating temperature.

2. Select “A/F SEN1 (B1)” or “A/F SEN1 (B2)” in “DATA MONITOR” mode with CONSULT.

3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
Does the indication fluctuate around 2.2 V?

YES

>> GO TO 4.

NO

>> Proceed to 

EC-219, "Diagnosis Procedure"

.

4.

PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B-I

1. Select “A/F SEN1 (B1) P1276” (for DTC P0130) or “A/F SEN1 (B2) P1286” (for DTC P0150) of “A/F

SEN1” in “DTC WORK SUPPORT” mode with CONSULT.

2. Touch “START”.

3. When the following conditions are met, “TESTING” will be displayed on the CONSULT screen.

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0130

A/F SENSOR1 (B1)
(O2 sensor circuit bank 1 
sensor 1)

A)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is constantly in a range other 
than approx. 2.2 V.

• Harness or connectors

(The A/F sensor 1 circuit is open 
or shorted.)

• A/F sensor 1

B)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is constantly approx. 2.2 V.

P0150

A/F SENSOR1 (B2)
(O2 sensor circuit bank 2 
sensor 1)

A)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is constantly in a range other 
than approx. 2.2 V.

• Harness or connectors

(The A/F sensor 1 circuit is open 
or shorted.)

• A/F sensor 1

B)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is constantly approx. 2.2 V.