2007 Hyundai Tucson - Make the light go away

Engine light on ,I disconnect neg battery terminal light stayed on , I know no thermostat in cooling system. Any help please.

That is telling you there is a problem… we need the error codes

'Cause there still is a problem… we still need the error codes, in the form P1234. Most auto parts store will read them for free.

Well THAT could be your problem. The wrong or no thermostat will set a code in many cars.