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Home >> Ford >> 2007 >> Freestar SEL >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Powertrain DTC Charts And Descriptions (Except Diesel & Hybrid) >> DTC Diagnosis >> P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

P0128 - COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)

Description:  Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.
Possible Causes: 
  • Insufficient warm up time
  • Low engine coolant level
  • Leaking or stuck open thermostat
  • Inoperative engine coolant temperature (ECT) sensor
  • Inoperative cylinder head temperature (CHT) sensor
Diagnostic Aids:  Refer toTHERMOSTAT MONITOR for system information.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
Vehicles with only a CHT sensor - - refer to PINPOINT TEST DL .
All others - - refer to PINPOINT TEST DX .