Oven bake element. If the oven won't heat, the bake element may have burned out. Often, if the bake element has burned out, it will be visibly damaged. Inspect the bake element for holes or blisters.
Oven temperature sensor. The oven sensor works in conjunction with the oven control board to regulate the oven temperature. If the oven sensor is defective, the oven temperature will be inaccurate by more than 50 degrees Fahrenheit.