Temp Gauge problem
 

Hi all-I'm new here, and just had a quick question. I have a 2000 Mystique which I have owned since 2002. Recently I was driving the car and noticed that the temperature gauge was reading extremely high-just shy of the hot mark. I pulled over, shut off the car, and popped the hood. I didn't see any leaking coolant or steam, but just to be safe, I called AAA and had the car towed back to campus. I let it sit overnight, and when I went back out, I cranked it up to look for leaks or anything else out of the ordinary. When I cut the car on, the gauge still read extremely hot-I know that's impossible. Before I start playing the replace parts game, does anyone have any advice on where to go first? Bad temp sensor? Faulty wiring? Whats up?