There are a number of things that could cause the overheating issue. If the overheating happens immediately, it's probably the water pump. If this happens only when it's hot, see if it happens only when the AC is on because then it could be the an auxiliary AC cooling fan that has gone bad.
Get your radiator checked, may have blocked core
low anitfreeze, no water, busted headcap
could be low coolant due to a leak, clogged rad, inoperative cooling fan, thermostats.... overheating conditions can have alot of causes. you need to do some digging.
Possible causes for overheating include failed serpentine belt, failed water pump, internal or external coolant leak, restriction in the radiator, or inoperative radiator fan.
There are a few reasons a vehicle is overheating. The common causes are the thermostat, water pump, radiator, or the fan stopped working.
There are several causes that will reduce the water level in your car radiator. The most common cause is evaporation. Engine overheating will also reduce the radiator water level.
a 2002 Alero could have several problems causing the overheating. Thermostat, water pump, or clogged radiator issues are the most common causes of overheating.
Plugged radiator, Bad thermostat, water pump not working, radiator hoses collapsing and dont forget no oil
a bad termastat
The most common causes would be low coolant and inoperable radiator fan.
If the engine is overheating and you have checked all other causes of overheating. Start the engine cold and immediately remove the radiator cap. Look to see if you have flow. If not, the pump is more than likely bad. If the pump is leaking, making any noises, or the shaft can be moved from side to side, the pump is bad.
Overheating Low coolant Defective radiator cap Stuck thermostat