Direct answer: When the upper oven still works but the lower oven stays cold, the problem is usually inside the lower oven itself: a bad bake heat source, a weak igniter on gas models, or a lower oven temperature sensor that is reading wrong.
Most likely: Start with the lower oven settings, door closure, and whether the lower oven shows any heat at all. If it starts but never climbs, suspect the lower oven bake element on electric models or the lower oven igniter on gas models before you blame the control.
First separate no-heat from slow-heat. If the lower oven light, display, and fan behavior seem normal but food stays raw, you are usually chasing a heat-making part, not a power problem. Reality check: a lower oven that gets just a little warm is often closer to a part failure than a total electrical outage. Common wrong move: replacing the temperature sensor just because the oven temperature feels off, without checking whether the lower oven is actually making bake heat.
Don’t start with: Do not start by ordering a control board. On double ovens, a dead lower cavity is more often a lower-oven heating part than the main control.
The display responds and a cycle starts, but the lower oven never gives off real heat.
Start here: Start with settings, door closure, and whether the lower oven has an electric bake element or a gas igniter that should be heating.
The cavity may feel lukewarm after several minutes, but it never gets close to baking temperature.
Start here: This points more toward a weak bake element, weak igniter, or a sensor issue than a total power loss.
It eventually heats, but much slower than normal and cooking times are off.
Start here: Watch for one heat source failing while another still works. That is common on ovens that partly heat.
The lower oven may brown from the top or show some heat during broil, but normal baking fails.
Start here: Go straight to the lower oven bake side first. That pattern strongly fits a failed lower oven bake element or weak lower oven igniter.
When broil still works or the oven gets only a little warm, the lower bake element is the usual culprit. You may see blistering, a split spot, or a burned section.
Quick check: With power off and the oven cool, inspect the lower oven bake element for cracks, bubbles, or a break in the sheath.
A gas lower oven may glow but still not open the gas valve strongly enough. That gives you long preheat times or no real heat.
Quick check: Start bake and watch through the lower oven bottom access area if visible. A strong igniter should glow and lead to flame fairly quickly.
If the lower oven starts heating but shuts down early or never reaches the set temperature, a bad sensor can mislead the control.
Quick check: Look for a sensor probe mounted inside the lower oven cavity. If heating is weak rather than absent, keep this on the list after the main heat source.
If the lower oven has correct settings, the door is closed, the sensor looks intact, and the heat source never gets power, the control side becomes more likely.
Quick check: This is more likely when the lower oven never energizes bake or broil at all, while the upper oven and display still work normally.
Double ovens can be set to the wrong cavity, delayed start, timer mode, or a mode that is not actually calling for bake heat.
Next move: If the lower oven starts heating normally after a clean restart, the issue was likely a setting or door-closure problem. If the lower oven still stays cold or barely warms, move on to the heating pattern checks.
What to conclude: You have ruled out the easy false alarms before opening anything up.
The next move depends on how the lower oven makes heat. Electric models usually fail at the bake element. Gas models often fail at the igniter.
Next move: If the failure pattern clearly points to one heat source, you can inspect that part next instead of guessing. If you still cannot tell which style you have, use the owner documentation or model tag information before disassembling further.
What to conclude: A lower oven that partly heats usually has one failed heating component, not a mystery whole-oven failure.
This is the most common confirmed repair path when the lower oven will not bake.
Next move: If you find a visibly failed lower oven bake element or a clearly weak lower oven igniter, that is your repair path. If the heat source looks intact and the lower oven still does not heat right, check the sensor next.
A bad lower oven temperature sensor usually causes wrong temperature, short cycling, or slow heat rather than a totally dead oven, but it is common enough to verify before blaming controls.
Next move: If the lower oven temperature sensor is open, shorted, or far out of range, replacing it is a reasonable next step. If the sensor checks out and the lower oven still never energizes bake or broil correctly, the problem is more likely in wiring or the lower oven control side.
By this point, the common homeowner-fix parts are either confirmed or mostly ruled out.
A good result: If the lower oven now preheats at a normal pace and holds temperature, the repair path was correct.
If not: If the lower oven still will not heat after the confirmed part is replaced, stop and have the lower oven wiring and control circuit tested professionally.
What to conclude: You have covered the common field failures. What is left is usually a control or harness issue, and that is where DIY gets less efficient fast.
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That usually means the shared power supply is not the main problem. On a double oven, each cavity has its own heating parts, so a failed lower oven bake element, lower oven igniter, or lower oven temperature sensor is more likely than a whole-unit failure.
It can, but it more often causes wrong temperature, short cycling, or slow heating. If the lower oven is completely cold, the bake element on an electric model or the igniter on a gas model is usually the better first suspect.
That is a strong clue that the lower oven bake side has failed. On an electric oven, suspect the lower oven bake element. On a gas oven, suspect the lower oven igniter or burner ignition on the bake side.
Not first. Control problems do happen, but they are not the most common cause when one oven cavity quits heating and the rest of the unit still works. Check the lower oven heat source and sensor before going after controls.
A weak igniter often glows but does not light the burner promptly. The lower oven may take a very long time to preheat, may never reach temperature, or may stay mostly cold even though you can see some glow from the igniter.
A bad lower oven door gasket usually causes heat loss and uneven baking, not a totally cold oven. It matters more when the lower oven heats some but struggles to hold temperature.