A Bosch oven may not provide heat due to its igniter being damaged or its baking element being burnt out. There may also be an issue with the power supply, oven control board, or other wired components, according to Repair Clinic.
The most common cause for heating failure in an oven is damage to its igniter. Even if the oven igniter is glowing, it may be too weak to allow for the oven's gas valve to open. If the oven does not heat and the igniter glows for more than 90 seconds without igniting the gas flame, the igniter should be replaced.
The problem may also be the baking element, which is the black tube near the bottom of the oven. If operating normally, the bake element glows red hot. If the element does not glow, it may have burned out. An element that has burned out has either a hole in the element or blisters on the outside of the element.
It is also possible that the appliance is not receiving proper voltage due to a problem in the wiring. Sometimes the wire supplying power to the element burns out right near the element itself. Check for this by just looking at the wires leading to the element.
Finally, the oven control board may be malfunctioning. The oven control board usually cannot be tested and has to be replaced if it is defective.