thermostat issue

Hi ,

I was hoping someone could answer a question for me. My 2007 Solstice was stored for 8 years as it had some issues I did not think I could have repaired at the time but I had gone to a forum and they were great and told me sounded like a sensor and which ones to start  with and sure enough the 2 that are on top of the engine were the problem or one was I had this issue repaired by a dealership but still had the problem so we took a look and one was split in half the guy at the auto store said he had never seen something like that so that issue was fixed car drove great for a few weeks then one day I got out and there was what looked like antifreeze on the ground and sure enough it was dripping from the water pump that got repaired along with a new thermostat and drove great no leaks no sounds was great but now I am having another issue yesterday the engine light came on and not sure why so  when  came home I checked for leaks and there was none antifreeze was full. but when I check the temp it showed      coolant _ _ _ F    it did not show the temp the fan came on when it was sitting in driveway running. Is it possible it is a sensor ??

Thanks.

Donna