P0128
TECHNICAL DESCRIPTION- The ECM
DTC SET CONDITIONS
Check Area
- Engine coolant temperature is between -10 °C (14 °F) and 82 °C (180 °F) when the engine is started.
- The engine coolant temperature - intake air temperature is 5 °C (48 °F) or less when the engine is started.
- The intake air temperature when the engine is started - intake air temperature is 2 °C (36 °F) or less.
- The volume air flow sensors output frequency is in the low frequency (50 - 100 Hz or less) state for 300 seconds or less.
Judgment Criteria
- The time for the engine coolant temperature to rise to 82 °C (180 °F) takes longer than the specified time *.
*: Approximately 11 to 23 minutes when the engine coolant temperature at start is 20 °C (68 °F) or more.
Approximately 20 to 54 minutes when the engine coolant temperature at start is 20 °C (68 °F) or less.
- Only one monitor during one drive cycle.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- The thermostat is faulty
- ECU failed.
- PCM failed.
DIAGNOSIS
STEP 1. Check the cooling system.
Refer to Engine Cooling Diagnosis.
Q: Is the cooling system normal?
YES: Replace the ECM or PCM. Then check that the DTC P0128 does not reset.
NO: Repair it. Then check that the DTC P0128 does not reset.