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scottb ... 11/18/2012
2005 Dodge Ram 1500 Laramie 8 Cyl 5.7L - Engine
I have a check engine light - it is showing code P0128 - my truck has never overheated or lost coolant.
1 Answer
  • Jimm
    Jimm 11/19/2012
    P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). P0128 indicates the engine has not achieved the optimum temperature within the specified amount of time.

    Possible Causes:

    Low coolant level
    Stuck open thermostat
    Defective engine coolant temperature (ECT) sensor
    Defective intake air temperature (IAT) sensor
    Defective cooling fan
    Defective cooling fan relay

    Possible Solutions:

    Top off coolant
    Replace thermostat
    Replace engine coolant temperature (ECT) sensor
    Replace Intake air temperature (IAT) sensor
    Replace cooling fan
    Replace cooling fan relay

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