I just had a coolant hose replaced in my car last Friday and now it's overheating what could it be?

Hello, sometimes when a hose is replaced -- or another cooling system component, an air pocket may still be in the cooling system, which can cause overheating symptoms. Hopefully the air was purged when the hose was replaced. If it was not, and the engine overheated, other damage could have also occurred as a result. Have the system checked and purged of any air pockets and recheck -- if it overheats again, normal engine diagnostic testing will be required to find out why.