DTC P0128 Coolant Thermostat (Engine Coolant Temperature Below Thermostat Regulating Temperature): Trouble Symptom
WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
Thermostat remains open.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode < refer to
OPERATION , Clear Memory Mode. >, and Inspection Mode < refer to
PROCEDURE , Inspection Mode. >.
DIAGNOSIS PROCEDURE
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK FOR ANY OTHER DTC ON DISPLAY. | Is any other DTC displayed? | Check the appropriate DTC using the "List of Diagnostic Trouble Code (DTC)". < refer to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . > | Go to step 2 . |
| 2 CHECK ENGINE COOLANT. | Is the engine coolant amount normal? | Go to step 3. | Refill the engine coolant. < refer to ENGINE COOLANT . > |
3 CHECK RADIATOR FAN.
|
Does the radiator fan continuously rotate for 3 minutes or more during idling? | Repair radiator fan circuit. < refer to RADIATOR MAIN FAN AND FAN MOTOR > and < refer to RADIATOR SUB FAN AND FAN MOTOR . > | Replace the thermostat. < refer to THERMOSTAT . > |