Dash light lightning Bolt and more
 

So hey couple times I've started my 2008 jku and. The dash light lightning bolt came on the check engine light and my temp gauge didn't move at all after shutting it off and restarting at the gauge work. Lightning bolt was gone but check engine light was still on. The shop said the code was something to do with the thermostat. Any import your help would be appreciated thank you i have two new batteries all connections are good.