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

   Result 

   DTC RESULT REFERENCE
   
   

   Result	Proceed to
   P0128	A
   P0128 and other DTCs	B

   HINT:

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

   B: GO TO DTC CHART  (See DIAGNOSTIC TROUBLE CODE 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 THERMOSTAT ).
   2. Measure the valve opening temperature of the thermostat.

      Standard Value: 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 INSPECTION ).

   NG: REPLACE THERMOSTAT  (See THERMOSTAT )

   OK: REPLACE ECM  (See ECM )