Oven displays F21, heating stops or does not start, sometimes after prolonged high-temperature use.

Safety first: Turn off power before accessing the rear of the oven.

• Check sensor mounting: Ensure the sensor probe is firmly fixed into the cavity wall and has not been pulled out.
• Inspect wiring: Follow the sensor cable to the control board. Look for breaks, cuts, or unplugged connectors.
• Continuity test: Disconnect the sensor and measure resistance. Infinite resistance indicates an open sensor; replace it.
• Reconnect and secure: If the sensor is good, reseat the connectors at both ends and secure the cable away from sharp edges and hot surfaces.