An oven that won't heat can be repaired by replacing the igniter, bake element or broil element. Replacing the thermal fuse, oven control board or relay board may also solve the problem.
A weak or broken igniter is the most likely cause for a gas oven not to heat. If the igniter glows for 90 seconds or more without igniting the gas, it needs to be replaced. In electric ovens, failure to heat is often caused by either a malfunctioning bake or broil element. These elements are black, tube-like and about the same diameter as a pencil. They are positioned in the bottom or top of the oven, respectively. If either of these elements has holes or blisters on the surface, it must be replaced for the oven to function.
The thermal fuse is a safety mechanism that shuts off the oven if it gets too hot. Once this fuse has tripped, it cannot be reset and must be replaced for the oven to heat again. The oven control board and the relay board both control the electrical flow to the elements; however, only some models have the latter part. The oven control board cannot be tested but may need to be replaced if the other components of the oven are still functional. Likewise, if any of the circuits on the relay board have failed, the entire unit must be replaced.