Why Engine Coolant Temperature is Important

There are 3 main jobs that the antifreeze in coolant performs to keep the engine coolant temperature normal:

  1. It prevents the coolant from freezing during cold weather
  2. It raises the boiling temperature of the coolant to prevent overheating during hot weather
  3. It fights corrosion

Your vehicle is equipped with an Engine Coolant Temperature (ECT) Sensor screwed into the engine's block or cylinder head, which determines the temperature of the engine coolant. If the operating temperature exceeds what your owner's manual says is acceptable (usually between 200 and 230 degrees F), it's time to get your cooling system checked to avoid overheating, and a possible breakdown.

Possible Causes for Engine Coolant Temperature Fluctuation

  1. Leak in the cooling system letting the pressure drop which decreases the boiling point of the coolant
  2. Bad or stuck thermostat. Or bad radiator cap
  3. Low coolant allowing air to get into the system
  4. Bad water pump or drive belt
  5. Debris in front of the radiator restricting air flow
  6. Mechanical issues such as a bad head gasket
  7. Bad cooling fan or accessories

You can use OBDLink to keep an eye on your engine coolant temperature:

Engine Coolant Temperature Log