Display shows F09, oven may freeze or reboot, clock may reset.

Safety first: Disconnect the oven from mains before removing any panels.

Step-by-step checks:

• 1. Power cycle: Turn off power for 10–15 minutes to fully discharge the electronics. Restore power and check if F09 clears temporarily.
• 2. Check supply stability: Ensure the oven is on a dedicated circuit and that there are no obvious supply issues (flickering lights, tripping breakers). Persistent supply problems can corrupt memory.
• 3. Inspect control board: Access the main PCB and check for signs of moisture, corrosion, or insect damage around the memory IC.
• 4. Replace control module: In most domestic settings, F09 requires replacement of the Hotpoint-Ariston main control board pre-programmed for your model. Transfer all connectors one by one to avoid miswiring.

Note: Some models may require configuration or calibration after board replacement; follow the service manual or use an authorized technician.