LEMON Manuals: Even more car manuals for everyone
Home >> Subaru >> 2016 >> WRX Premium, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Engine Controls (Diagnostics) (H4DOTC) (WRX-STI)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0128 Coolant Thermostat (Engine Coolant Temperature Below Thermostat Regulating Temperature) >> Trouble Symptom

DTC P0128 Coolant Thermostat (Engine Coolant Temperature Below Thermostat Regulating Temperature): Trouble Symptom

WARNING: This page is about a different variant/trim than selected.

Thermostat remains open.

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. >, and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.
DIAGNOSTIC 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)". < Ref. 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. < Ref. to ENGINE COOLANT . >
3 CHECK RADIATOR FAN. 
  1. Start the engine.
  2. Check the radiator fan operation.
Does the radiator fan continuously rotate for 3 minutes or more during idling? Repair radiator fan circuit. < Ref. to RADIATOR MAIN FAN AND FAN MOTOR . > < Ref. to RADIATOR SUB FAN AND FAN MOTOR . > Replace the thermostat. < Ref. to THERMOSTAT . >