Many San Antonio kitchens cook on natural gas supplied by CPS Energy. Gas ovens are durable, but they have a few characteristic failures, and the best known, a weakening igniter, is easy to recognize once you know what to watch for. This guide covers a gas oven that won't heat or takes too long to preheat, an oven that runs hot or cold, and the safety steps that come before any troubleshooting.
Safety first: if you smell gas
A faint whiff for a moment when a burner lights can be normal. A persistent smell of gas is not.
- •Don't turn anything on or off, including lights, the oven, and the exhaust fan. Don't use a phone inside the house.
- •Don't try to find the leak.
- •Get everyone out of the house, leaving the door open behind you.
- •From outside, at a safe distance, call CPS Energy's gas emergency line or 911.
Don't go back inside until you're told it's safe. Everything below assumes there's no gas smell.
How a gas oven lights
Most gas ovens built in the last few decades use a hot surface igniter, sometimes called a glow bar, rather than a pilot light. When you set a temperature, the igniter heats up and glows orange. It's wired in series with the oven's gas safety valve, and the valve only opens once the igniter is drawing enough current, which happens when it's hot enough to light the gas. The gas then flows, lights on the glowing igniter, and the oven heats.
As igniters age, their resistance rises and they draw less current. A weak igniter can still glow brightly, but it never reaches the current the valve needs. So the valve doesn't open, or opens only after a long delay.
Symptoms of a weak igniter
- •The igniter glows, but the burner doesn't light for a long time, or at all.
- •Preheating takes much longer than it used to.
- •The oven lights and then won't relight when the thermostat cycles, so the temperature drops during baking.
- •You hear a soft "whump" as a larger than normal amount of gas lights at once after a delay.
To look at it, remove the oven racks and the bottom panel if your model allows it (some lift out, some are fixed). The bake igniter usually sits beside the burner under the floor of the oven. Set the oven to bake and watch through the slots without putting your face close. If the igniter glows for well over a minute with no flame, the igniter is the most likely cause.
A glowing igniter is fragile and very hot. Don't touch it, and don't try to clean it.
If you see no glow at all, the fault may be the igniter, the control, or the wiring. That's a job for a technician.
Oven temperature running hot or cold
If recipes come out underdone or burnt at the stated times, check the oven's real temperature before calling anyone.
- Use a separate oven thermometer placed in the center of the middle rack.
- Preheat to 350 °F, then give the oven another 15 to 20 minutes after it says it's ready.
- Read the thermometer several times over the next half hour without opening the door for long. Ovens cycle above and below the setpoint, so average the readings.
A small difference is normal. A consistent difference of 25 °F or more is worth addressing.
Adjusting the offset
Many ovens with digital controls let you adjust the calibration offset by a limited amount through a button sequence in the settings. The procedure varies by brand and model, so follow the manual. If an offset brings the average back in line, you're done.
When calibration won't fix it
If the error is large, changes from day to day, or gets worse over time, the cause is usually a part:
- •A weak igniter that lets the temperature fall while waiting to relight.
- •A failing temperature sensor (a thin probe at the back of the oven cavity).
- •A control board fault.
- •A worn door gasket or a door that doesn't close fully, letting heat escape. Check that the door isn't caught on anything and the gasket isn't torn or flattened.
Things to rule out first
- •The oven control lock or a delay-start setting may be active. Check the display.
- •The gas supply. If the cooktop burners light normally, gas is reaching the range. If nothing lights, check that the shutoff valve behind the range is open.
- •A tripped breaker or GFCI. A gas range still needs electricity for the igniters and controls.
- •A range pulled out for cleaning may have its gas connector kinked or its power cord partly unplugged.
If you pull a gas range out, move it slowly and don't let the gas connector take the strain. If the connector is old, stiff or looks corroded, have it replaced rather than bending it back.
When to call a technician
Call for service if:
- •The igniter glows without lighting the burner or takes much longer than a minute.
- •The oven doesn't heat at all, with no glow.
- •The temperature error is large or inconsistent after checking with a thermometer.
- •Burner flames look yellow and lazy instead of mostly blue, or you see soot on the oven walls. That can mean poor combustion and should be checked soon.
- •You smell gas at any point. Follow the safety steps above first.
The bake igniter is a known wear item on gas ovens, and replacing it is usually straightforward once it's confirmed as the cause. Our oven repair and range repair pages explain how we diagnose gas and electric units. If the problem is on top of the range rather than inside it, see our guide to a gas cooktop burner that won't light.
Frequently asked questions
How long should a gas oven take to light?
It varies by model, but a hot-surface igniter oven typically lights within about a minute to a minute and a half. If yours used to light quickly and now takes noticeably longer, the igniter is probably weakening.
Can I replace an oven igniter myself?
It involves gas components and wiring. Many homeowners prefer to have a technician do it, and if you aren't comfortable turning off the gas and power and working around the burner, don't attempt it.
Is it safe to use the oven while the igniter is weak?
A weak igniter is a performance problem rather than a leak, because the valve stays closed until the igniter is hot enough. But delayed ignition can cause a loud whump, and you shouldn't ignore it. Have it replaced.