The fan oven mode is not working, there is no hot air circulation, and F04 is displayed when selecting fan-assisted cooking.

Safety first: Disconnect mains power and wait for the oven to cool completely.

• Check fan operation: Select fan mode with the oven cold and listen. If the fan does not spin at all (after temporarily restoring power for this test), suspect the fan motor or its power supply. Do not run for more than a few seconds if there is a fault.
• Access fan assembly: Remove the oven's rear inner panel (inside the cavity) to expose the fan blade and fan element. Inspect for heavy grease buildup or obstructions preventing rotation.
• Spin test: With power off, try to spin the fan blade by hand. It should rotate freely. If it is stiff or seized, replace the convection fan motor.
• Test fan element: Disconnect the fan element terminals and measure resistance. Typical values are 20–60 Ω. If it is an open circuit, replace the fan element.
• Inspect wiring: Check for burnt or loose connectors at the fan motor and element. Repair or replace any damaged wiring.
• Control PCB relay: If the motor and element test good but F04 persists, the fan relay on the control PCB may have failed. Replace the main control PCB if relay contacts are burnt or the relay does not energize.