Inspection Procedure

HINT:

Read freeze frame data using Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).

1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0128) 
   1. Connect Techstream to the DLC3.
   2. Turn the Engine switch on (IG).
   3. Turn the tester on.
   4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
   5. Read the DTC.

      Result 

      RESULT REFERENCE CHART
      
      

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

      HINT:

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

   B: GO TO DTC CHART

   A: Go to next step 

2. CHECK COOLING SYSTEM 
   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.

   NG: REPAIR OR REPLACE COOLING SYSTEM 

   OK: Go to next step 

3. INSPECT THERMOSTAT 
   1. Remove the thermostat (See INSPECTION ).
   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.

   3. Reinstall the thermostat (See INSTALLATION ).

   NG: REPLACE THERMOSTAT 

   OK: REPLACE ECM