Oven overheats, food burns quickly, or temperature far above set value

Safety first: Isolate the oven from mains power before removing any covers.

• Verify symptom: Use an oven thermometer to compare actual temperature to the set temperature. If the oven overshoots by more than ~30–40°C, suspect a sensor or control issue.
• Locate the NTC sensor: Inside the oven cavity, usually at the rear upper area. Remove the mounting screw and gently pull the sensor into the cavity to access the connector from behind (may require removing the rear or top cover).
• Check wiring and connector: Inspect the sensor cable for heat damage or cuts. Ensure the connector is firmly seated on the control board and free of corrosion.
• Measure sensor resistance: At room temperature, measure across the sensor pins. Compare to Grundig service data (commonly around 500–1100 Ω at 20–25°C). If reading is open, shorted, or unstable when gently flexed, replace the sensor.
• Inspect control board: If the sensor tests OK, the temperature regulation circuit or relay on the main PCB may be faulty. Look for burnt components or cracked solder joints. Board-level repair should be done by a professional.
• Reinstall sensor correctly: Ensure the sensor tip is fully inside the cavity and not touching metal panels directly, which can cause false readings.

Warning: Do not continue using an oven that overheats; it can damage cabinetry and pose a fire risk.