An oven that takes much longer than it used to reach temperature usually has a weakening bake element (electric) or igniter (gas), a temperature sensor reading wrong, or a door that is leaking heat. Start by confirming the problem with a cheap oven thermometer, because the oven’s own display and beep can be wrong.
Confirm it with a thermometer
- Place an oven thermometer on the middle rack
Use a freestanding oven thermometer, not the oven’s display.
- Preheat to a common temperature and time it
Set 350°F (175°C) and note how long the oven takes to beep, then read the thermometer at the beep.
- Compare after another 10 minutes
If the thermometer is far below the set temperature when the oven beeps, the oven is not heating properly. If it matches, the oven is reaching temperature and the only issue is time.
The usual causes
| What you notice | Likely cause |
|---|---|
| Preheats slowly, bake element looks dull or patchy when on | Electric bake element weakening |
| Gas oven takes a long time to light or burn steadily | Weak igniter or dirty burner |
| Beeps early but the thermometer is far lower | Temperature sensor reading wrong or calibration off |
| Heat escapes around the door | Worn or damaged door gasket |
| Slow only with convection or with several pans | Airflow and load, not a fault |
Weak bake element (electric)
A bake element ages in a way that is easy to miss: it still glows, but heats less. Look at it in a dark kitchen while preheating. Blisters, cracks or a section that stays dark are signs of failure. Our oven not heating guide and element guide show how to check it, and replacement is a simple, inexpensive repair on most ovens when the power is off.
Weak igniter (gas)
A gas oven igniter that has weakened can glow but not pass enough current to open the gas valve promptly. The result is a long delay before the flame appears. Gas work should stay with a professional — see what is safe to check on a gas oven.
Temperature sensor and calibration
The sensor is a thin probe at the back of the oven cavity. If it drifts, the oven can think it is hotter than it is, ending preheat early, or cooler than it is, overheating. Many ovens let you adjust the temperature offset in the settings menu; check your manual. If the oven is also uneven, see oven heats unevenly.
Door seal and loading habits
Check the door gasket for gaps, tears or flat sections, and make sure the door closes completely (oven door won’t close). Remove spare baking sheets and pizza stones that soak up heat, and avoid opening the door to peek. A heavy pan or stone left inside can add many minutes to the preheat.
When to call a technician
If the thermometer shows the oven genuinely struggles to reach temperature, and an element or igniter is not the obvious culprit, the control board or sensor is the next suspect. See our oven repair cost guide before deciding between repair and replacement.
