Yes, all Dacor® Ovens need to be preheated, regardless of whether you are using a convection mode or not. In some modes, more than one element is used during preheat, which can cause the food to burn. The oven will tone when it has finished a preheat cycle, and the small "On" icon on the control panel will disappear. Always start with a hot oven or a hot pan. This gives you better control of your heat.