DTC P0128: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
- OUTLINE OF DIAGNOSIS
Detect the malfunction of thermostat function.
Judge NG when the engine coolant temperature is lower than the estimated engine coolant temperature and the difference between them is large. Judge OK when the engine coolant temperature becomes 75°C (167°F) and the difference is small before judging NG.
- COMPONENT DESCRIPTION
- ENABLE CONDITION ENABLE CONDITION CHART
Secondary Parameters Enable Conditions None - GENERAL DRIVING CYCLE
Always perform the diagnosis continuously.
- DIAGNOSTIC METHOD
- Abnormality Judgment
Judge NG when the continuous time of completing the malfunction criteria below becomes more than 30 seconds.
Judgment Value
JUDGMENT VALUE CHARTMalfunction Criteria Threshold Value Battery voltage "GREATER THAN EQUAL TO" 10.9 V Estimated ambient air temperature "GREATER THAN EQUAL TO" 7°C (19.4°F) Engine coolant temperature at engine starting > 55°C (131°F) Estimated coolant temperature "GREATER THAN EQUAL TO" 75°C (167°F) Engine coolant temperature > 75°C (167°F) (Estimated - measured) coolant temperature < 30°C (86°F) Time Needed for Diagnosis: 30 seconds
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
- Normality Judgment
Judge OK and clear the NG when the malfunction criteria below are completed.
Judgment Value
JUDGMENT VALUE CHARTMalfunction Criteria Threshold Value Battery voltage "GREATER THAN EQUAL TO" 10.9 V Estimated ambient air temperature "GREATER THAN EQUAL TO" -7°C (19.4°F) Thermostat malfunction diagnosis Not finished Engine coolant temperature at engine starting > 55°C (131°F) Engine coolant temperature "GREATER THAN EQUAL TO" 75°C (167°F) (Estimated - measured) coolant temperature "LESS THAN EQUAL TO" 30°C (86°F) - DTC CLEAR CONDITION
- When the OK idling cycle was completed 40 times in a row
- When "Clear Memory" was performed
- MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle was completed 3 times in a row
- When "Clear Memory" was performed
- FAIL SAFE
None
- ECM OPERATING AT DTC SETTING
- Memorize the freeze frame data. (For test mode $02)
- Memorize the diagnostic value and trouble standard value. (For test mode $06)