How to test it properly
- Place an oven thermometer in the center of the middle rack.
- Set the oven to 350°F and let it preheat, then wait another 15 minutes.
- Take readings every 5 minutes for 20 minutes and average them.
- An average within about 15–20°F of the setting is normal.
Most likely causes
- Calibration drift over years of use.
- Failing temperature sensor, the thin probe at the back of the oven cavity.
- Worn door gasket letting heat escape.
- Weak bake element or igniter that can't keep up.
- Control board misreading the sensor (less common).
Try this before you book
- Look up your model's calibration setting. Most digital ovens allow up to a 35°F adjustment.
- Check the door gasket for gaps, flattening, or tears.
- Make sure the sensor probe isn't touching the oven wall.
Parts we replace most often
- Temperature sensor
- Door gasket
- Bake element
- Control board
Fix it or replace it?
Temperature accuracy problems are almost always cheap to fix. Sensors and gaskets are inexpensive parts, and calibration is often just a setting change. This is rarely a reason to shop for a new oven.
From John's notes: Cheap oven thermometers can be off by 20 degrees themselves. If your readings look strange, test with a second thermometer before deciding the oven is the problem.
Recipes keep failing? Book an oven repair with TrueFix Appliance Repair Dallas.