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 ENGINE COOLANT. | Is the engine coolant amount normal? | Go to step 2 . | Refill the engine coolant. < Refer to ENGINE COOLANT . > |
2 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 . > < Refer to RADIATOR SUB FAN AND FAN MOTOR . > | Replace the thermostat. < Refer to THERMOSTAT . > |