The check engine light is a signal from the computer that there is a potential problem that must be addressed. When the light comes on it is a signal that the computer has stored a problem code that you can read using a code scanner. You can borrow, rent or buy one at most auto parts retailers.
Most likely, the temperature gauge's connection is loose. It is usually on the thermostat. An inoperative temperature gauge will cause most check engine lights to come on.
Check the temperature sensor.
check the antifreeze
The check engine light is a " picture " of an engine , just to the left of the engine temperature gauge
temperature gauge not working can be caused by a bad temp sensor in engine, a bad gauge in dash, or a bad fuse
try replacing the thermostat
mechanical engine trouble. its about to blow up.
Check to make sure that the temperature sensor is good. A bad sensor is commonly the cause of the temperature gauge not working.
Coolant Temperature Sensor
An inoperative temperature gauge will not alter how an engine runs, but the operator will not know if the water temperature has risen above normal without a properly working guage.
The engine is overheating. The check engine light is not on because you have no problem with the emissions system which this light monitors.
On a 1997 Ford Explorer : CHECK ENGINE is just to the left of the " C " on the engine coolant temperature gauge ( Helpfull )