Inspection Procedure

HINT:

Read freeze frame data using the 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.

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

      Result 

      RESULT REFERENCE
      
      

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

      HINT:

      If any other codes besides P0128 are output, perform the troubleshooting for those DTCs first.

   B: GO TO RELEVANT 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 an abnormal radiator fan operation or a modified cooling system.
   2. Check the valve opening temperature of the thermostat.

      OK: Valve opening temperature is 80 to 84°C (176 to 183°F) 

      HINT:

      Also check that the valve is completely closed below the opening temperature shown above.

   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 (See INSPECTION ).

      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