[gsodonis]

For the week, I have been getting an intermittent CEL. First thing in the morning, it goes on within the first few minutes of driving (the engine and fluids are still cold), stays on for about ten seconds, goes off and then I don't see it again all day. I did the diagnostic today and I get the CEL code of 21: Coolant Temperature Sensor.

Has anyone had this CEL?
What does it mean? (What's wrong)
What should I do?

Thanks in advance for your help.