DTC P0128: Thermostat [09/2015 - 09/2016]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Trouble Codes.
5. Read the DTC.

   Result

   Display (DTC Output)	Proceed to
   P0128	A
   P0128 and other DTCs	B

   HINT: 

   If any DTCs other than P0128 are output, troubleshoot those DTCs first.

Result:  B

B 

GO TO DTC CHART 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [09/2015 - 09/2016] )

Result:  A

A 

See step  2

1. Check for defects in the cooling system that might cause the system to be too cold, such as abnormal radiator fan operation or any modifications.

Result:  NG

NG 

REPAIR OR REPLACE COOLING SYSTEM 

Result:  OK

OK 

See step  3

1. Remove the water inlet with thermostat (Refer to REMOVAL [09/2015 - ] ).
2. Check the valve opening temperature of the thermostat.

   Standard

   80 to 84°C (176 to 183°F)

   HINT: 

   In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

Result:  NG

NG 

REPLACE WATER INLET WITH THERMOSTAT 

(Refer to REMOVAL [09/2015 - ] )

Result:  OK

OK 

See step  4

1. Inspect the engine coolant temperature sensor (Refer to INSPECTION [09/2015 - ] ).

   HINT: 

   Perform "Inspection After Repair" after replacing the engine coolant temperature sensor (Refer to INITIALIZATION [09/2015 - ] ).

Result:  OK

OK 

REPLACE ECM 

(Refer to REMOVAL [09/2015 - ] )

Result:  NG

NG 

REPLACE ENGINE COOLANT TEMPERATURE SENSOR 

(Refer to REMOVAL [09/2015 - ] )