Coolant Temp Sensor Code

I have a 97 grand prix gt 3.8 non supercharged. I got a ses light on earlier today...so I pulled into autozone... The code read P0118 Engine Coolant Temp Circuit high Input. so I bought a new CTS and put it in. code came back on and I cleared it. Now code is gone and car is 210+ on startup, with fans not running. please help what can I do?

Did you put any thread sealer on the sensor prior to installing it? If you did, it's not getting a good ground. If not, the new sensor you got is bad or there is a problem with the wiring to it.