As overheating is the result of misuse of the mixer, review the recipe and make changes to it and make sure that the mixer is not on too high of a setting. Overheating occurs when the mixer is being overworked, such as when too much flour is added at once.
KitchenAid mixers tend to overheat when using recipes not made for the mixer itself. These cases often occur when a flour mix is added all at once, giving the mixer too much strain in order to properly mix the flour with the liquid ingredients. Avoiding this requires adjusting the recipe by slowly adding flour to the liquid ingredients in the bowl as it mixes, usually only a couple of cups at a time, until enough flour has been added.
If a KitchenAid mixer is set to too high of a setting, the machine may overheat very quickly. The gears, working harder than a lower setting, cause more heat when overworked at higher settings, forcing the mixer to shut down. Slower settings help avoid this problem.
If the machine continues to overheat even when the previous methods are tried, it is time to consult the official KitchenAid support page. Appliances are registered there and support can be found for any appliance; this helps troubleshoot any overheating problems the appliance is having.