I'm not very handy or car smart. But Autozone checked the engine light that came on in the wife's 2015 Jeep Grand Cherokee. Said it was a code for low temperature. Googled it and all said to replace thermostat. Checked YouTube to learn how to change the thermostat. It was very easy. Kinda messy, though. Spilled a lot of radiator fluid. Do the change outside or have a way to catch all that liquid. All-in-all it was very easy. The check engine light hasn't clicked off yet, but online says it can take up to two weeks for the computer to figure it out.
What kind of vehicle do you drive? 2015 Jeep Grand Cherokee