Oven overheats rapidly; display shows F2 and beeps, often during baking or self-clean.

Safety first: Turn off power at the breaker and allow the oven to cool completely before inspection.

• Visual check: Open the oven door and locate the temperature sensor probe (usually a thin metal rod at the rear wall, upper corner). Inspect for damage, kinks, or burnt insulation.
• Check sensor resistance: With power off, remove the rear panel or top cover to access the sensor connector. Disconnect it and measure resistance with a multimeter. A typical Kuppersbusch NTC sensor is around 1 kΩ–1.1 kΩ at 20–25°C. If reading is very low (near 0 Ω) or very high (open circuit), the sensor is faulty.
• Inspect wiring: Follow the sensor harness to the control board. Look for pinched, burnt, or loose wires, especially where they pass near the oven cavity.
• Control relay check: If the sensor tests good, the bake or grill relay on the main control board may be welded closed, causing overheating. Look for heat discoloration or burnt spots on the PCB.
• Replace components: Replace the oven temperature sensor (NTC probe) if out of spec. If the relay is stuck or the board is damaged, replace the main control module.

Note: After replacing parts, run a low-temperature bake (e.g., 120°C) and verify that the oven cycles on and off without triggering F2.