Before checking anything: if you smell gas at any point, stop, turn off the burner, ventilate the room, and contact your gas utility's emergency line before doing anything else — that's a safety issue, not a repair one.
1. Igniter too weak to open the gas valve
This is the single most common cause of a gas oven not heating. The igniter has to glow hot enough to draw enough current to trip the safety valve open. As an igniter ages, it weakens — it can still glow, sometimes even glow orange, and still never get hot enough to open the valve, so gas never flows and the oven never lights.
DIY checks: Watch the igniter through the oven window for about 30-90 seconds after turning the oven on. If it glows the whole time and nothing ignites, that's the classic weak-igniter symptom.
When to call a pro: A weak igniter should be replaced, not left to keep drawing gas without lighting. Don't keep re-trying it — call for service.
2. Igniter not glowing at all
If the igniter doesn't glow at all when the oven is turned on, the igniter itself has likely failed completely, or there's a wiring or control board fault preventing power from reaching it.
DIY checks: Confirm the oven is otherwise powered (display lit, other functions responsive) to rule out a bigger power issue before assuming it's the igniter.
When to call a pro: Igniter replacement and the wiring behind it are worth diagnosing properly rather than guessing which component failed.
3. Gas safety valve failure
Even with a good igniter, the safety valve itself can fail to open. This is less common than an igniter issue but produces a similar symptom — igniter glows normally, still no flame.
DIY checks: There isn't a safe visual DIY check for the valve itself — this is tested with the igniter isolated to confirm which component is actually at fault.
When to call a pro: Gas valve work should be diagnosed and handled by a technician — this isn't a guess-and-swap part.
4. Gas supply not fully on
If any other work has been done in the kitchen recently — a range installation, a gas line inspection, even moving the range to clean behind it — the shutoff valve behind the unit can end up partially closed without anyone noticing.
DIY checks: If it's safe and accessible, confirm the shutoff valve behind the range is fully open. If you're not sure or can't reach it safely, treat this as a call-a-pro item.
When to call a pro: If the valve is confirmed open and the problem continues, the cause is inside the appliance, not the supply line.
5. Oven temperature sensor or control board fault
This one's a different symptom — the oven actually ignites, but runs hot, cold, or won't hold the set temperature. That points toward the temperature sensor or control board rather than the ignition system.
DIY checks: Verify with an independent oven thermometer before assuming there's a real fault — built-in displays can be off by more than expected even when nothing's actually broken.
When to call a pro: If an independent thermometer confirms a real temperature problem, that's a sensor or control-board diagnosis worth doing properly.
6. Door seal or gasket wear
If the oven ignites and the burner clearly runs, but food isn't cooking properly or the oven never feels like it reaches temperature, a worn door seal letting heat escape can be the real cause rather than anything in the ignition system.
DIY checks: Close the door on a piece of paper near different points around the seal — if it slides out easily, the gasket may be worn.
When to call a pro: Gasket replacement is a straightforward repair once confirmed, but worth confirming it's actually the seal and not a temperature sensor issue first.