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DTC P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)

DTC P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)

DTC DETECTING CONDITION:


• Two consecutive driving cycles with fault

• GENERAL DESCRIPTION


TROUBLE SYMPTOM:

Thermostat remains open.

Important

After repair or replacement of faulty parts, conduct Clear Memory Mode and Inspection Mode .


CHECK VEHICLE CONDITION.

Was the vehicle driven or idled with the engine partially submerged under water?

Yes

In this case, it is not necessary to inspect DTC P0128.


No


CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Yes

Inspect the relevant DTC using “List of Diagnostic Trouble Codes (DTC)”.


No


CHECK ENGINE COOLANT.

Are coolant level and mixture ratio of cooling water to anti-freeze solution correct?

Yes


No

Replace the engine coolant.


CHECK RADIATOR FAN.

Start the engine.

Check radiator fan operation.

Does the radiator fan continuously rotate for more than 3 minutes during idling?

Yes

Repair radiator fan circuit. and .


No

Replace the thermostat.