Could be lots of things. You should have it checked for codes. The temp gauge problem would make me think of a possible temp sensor problem. It should be located near the thermostat housing.
Do you mean the cooling fan? If so engine temperature has excedded 235 degrees Check coolant level
water pump, oil, water, engine coolant....main cause would be engine coolant, just check to see if you have a leak.
Yes, on some vehicles it can.
It requires a scanner to properly diagnosis a check engine light.
Several things could cause the 2001 Impalas check engine light to stay on. Since so many things could be wrong, check the computer codes for any leads on possible problems.
A low battery can cause the electrical system to flash check engine lights
Replace your thermostat had same problem it sets a code but no check engine light
well, check your oil, engine coolant, and your radiator.
A defective thermostat can cause the engine to overheat. It can also cause the engine to not reach full operating temperature if the thermostat is stuck open. It is possible this could set the check engine light.
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.
A lot of parts stores will check it for free
Assuming you want to clear/reset the check engine light, if you have successfully made repairs to correct what was the cause of the check engine light to go on the light will clear itself after a few drive cycles.