P0128
DTC P0128 THERMOSTAT FUNCTIONOn Board Diagnosis Logic
DTC Confirmation Procedure
NOTE: If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.
TESTING CONDITION:
- For best results, perform at ambient temperature of -10 °C (14 °F) or higher.
- For best results, perform at engine coolant temperature of -10 °C (14 °F) to 71 °C (160 °F).
- Before performing the following procedure, do not fill with the fuel
WITH CONSULT-III
1. Turn A/C switch OFF.
2. Turn blower fan switch OFF.
3. Turn ignition switch ON.
4. Select "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT-III.
5. Check the indication of "COOLAN TEMP/S".
If it is below 71 °C (160 °F), go to following step.
If it is above 71 °C (160 °F), cool down the engine to less than 71 °C (160 °F). Then go to next steps.
6. Start engine and wait at idle for at least 30 minutes.
If "COOLAN TEMP/S" increases to more than 71 °C (160 °F) within 30 minutes, turn ignition switch, OFF because the test result will be OK.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
WITH GST
Follow the procedure "WITH CONSULT-III".
Diagnostic Procedure
Step 1-2:
Component Inspection
ENGINE COOLANT TEMPERATURE SENSOR
1. Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.
2. If NG, replace engine coolant temperature sensor.