I think that most probably your temperature sensor is gone. You know how our weather is these days. A couple days back, I was doing an oil change and after removing the oil filter and draining s**t out, I came to realize that I could not get the engine oil cap off. The cap just kept rotating and clicking. I had to snap the bastard into 2 pieces and kept the bottom piece. I took a good look into the cap and the plastic pieces on the top part that are supposed to hold the bottom piece, were all melted.