Diagnosis
A faulty oven temperature sensor or a significant calibration error. The sensor is a thin metal rod in the back of the oven.
How to Fix It
Run the oven's built-in calibration offset feature.
1. Press and hold the "Bake" and "Broil" buttons on the control panel simultaneously for about 5 seconds until the display shows the current offset (like "0" or "+15").
2. Use the up/down arrows to adjust the offset (e.g., if food is burning, lower the temperature by setting a negative offset like -10°F).
3. Press "Start" to save. Test with an independent oven thermometer.
If That Didn't Work
The oven temperature sensor (thermistor) is likely out of spec. Test its resistance with a multimeter when the oven is at room temperature. If the reading doesn't match the standard chart (about 1100k ohms at 77°F), replace the sensor.
Heads Up
Always use an external oven thermometer to verify temperature, don't trust the display alone. Also, avoid using dark, non-stick pans on the bottom rack—they absorb more radiant heat from the burner and will cause bottom burning regardless of calibration.