The 5 most common part(s) or condition(s) which cause the symptom Oven won't heat are listed below starting with the most likely. Check or test each item and watch any available videos.
RepairClinic Item # 1990
Even though the oven igniter may be glowing, it may be too weak to allow the gas valve to open. If the oven won't heat and the oven igniter glows for more than 90 seconds without igniting the gas flame, the oven igniter should be replaced. This is the most common part that fails when the oven won't heat.
Although not as common, if the oven won't heat it is possible that the appliance is not receiving proper voltage. Electric ovens require 220 volts of alternating current. If for some reason the appliance is receiving significantly less, the oven won't heat. Check for proper voltage using a volt meter at the socket where the appliance plugs in. For more information on this see the How It Works video above.
RepairClinic Item # 1810619
The oven control board has a set of relays that turn on and off power to the bake and broil circuits according to the customer settings and sensor input. If the oven won't heat the problem is usually with the heating components. However, if the oven control board is bad, it might not send voltage to the heating components. To determine why the oven won't heat, first test the simpler components in the circuit. The oven control board can't be tested easily and will have to be replaced if it is defective.
If the oven won't heat, there might be a burnt wire supplying power to the bake element. 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. If they're burned out it is usually easy to spot.
RepairClinic Item # 1556013
If the gas oven won't heat the oven valve and pressure regulator might be at fault. This is not common. Very often people misdiagnose a defective oven valve and pressure regulator when the oven won't heat. However, this is almost never the cause. First, inspect the other more common components before replacing these.