P0128

DTC P0128 THERMOSTAT FUNCTION

On Board Diagnosis 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 stuck open.

Malfunction is detected when the engine coolant temperature does not reach to specified temperature even though the engine has run long enough.

Possible Cause
- Thermostat function
- Leakage from sealing portion of thermostat
- Engine coolant temperature sensor

DTC Confirmation Procedure

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:
- For best results, perform at ambient temperature of -10 °C (14 °F) or higher.
- For best results, perform at engine coolant temperature of -10 °C (14 °F) to 60 °C (140 °F).

WITH CONSULT-II
1. Replace thermostat with new one. Refer to "THERMOSTAT AND THERMOSTAT HOUSING". Use only a genuine NISSAN thermostat as a replacement. If an incorrect thermostat is used, the MIL may come on.
2. Turn ignition switch "ON".
3. Select "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT-II.
4. Check that the "COOLAN TEMP/S" is above 60 °C (140 °F).
If it is below 60 °C (140 °F), go to following step.
If it is above 60 °C (140 °F), stop engine and cool down the engine to less than 60 °C (140 °F), then retry from step 1.
5. Drive vehicle for 10 consecutive minutes under the following conditions.
VHCL SPEED SE 80 - 120 km/h (50 - 75 MPH)
If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

WITH GST
1. Follow the procedure "WITH CONSULT-II" above.

Diagnostic Procedure Step 1:

Diagnostic Procedure

Component Inspection

Reference Data:

ENGINE COOLANT TEMPERATURE SENSOR
Check resistance as shown in the figure.

If NG, replace engine coolant temperature sensor.

Removal and Installation

ENGINE COOLANT TEMPERATURE SENSOR
Refer to Engine/Diagrams: Outer Component Parts