DTC - General Description

DTC P0128 COOLANT THERMOSTAT (ENGINE COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)

1. OUTLINE OF DIAGNOSIS
Detect malfunctions of the thermostat function.
Judge as NG when the engine coolant temperature is lower than the estimated engine coolant temperature and the difference between them is large. Judge as OK when the engine coolant temperature becomes to 75° C (167° F), and the difference is small, before judging NG.

2. COMPONENT DESCRIPTION






3. ENABLE CONDITION






4. GENERAL DRIVING CYCLE
Always perform the diagnosis continuously.

5. DIAGNOSTIC METHOD

- Abnormality Judgment
If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.






Time Needed for Diagnosis: 64 ms x 3 time x 120 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

- Normality Judgment
Judge as OK and clear the NG if the continuous time while the following conditions are established is more than the predetermined time.






Time Needed for Diagnosis: Less than 1 second

6. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

7. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed

8. FAIL SAFE
None

9. ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)