Oven shows F03 and does not heat or shuts down during preheat

Safety first: Disconnect mains power. Allow the oven to cool completely before working on it.

Step-by-step checks:

• 1. Check for obvious overheating: Look for signs of heat damage around the control panel, top cover, and rear panel. Ensure the oven is not tightly enclosed without ventilation as per Zanussi installation instructions.
• 2. Locate safety thermostat: Many Zanussi ovens have a safety thermostat or thermal cut-out mounted on the top of the oven cavity or near the control panel. Some are manual reset types with a small button.
• 3. Attempt reset: Press the small reset button (if present) on the safety thermostat until you feel a click. Restore power and test. If it trips again, investigate cooling and fan operation.
• 4. Test thermostat continuity: With power off, disconnect the thermostat wires and check continuity. An open circuit on a non-resettable device means it must be replaced.
• 5. Check cooling fan: Start a program and listen for the tangential cooling fan (behind the control panel). If it does not run, test the fan motor and its supply from the PCB. Replace the cooling fan if faulty.
• 6. Replace faulty parts: Replace a failed safety thermostat or thermal cut-out with the correct Zanussi part. Ensure all wiring is reconnected securely.

Warning: Never bypass a safety thermostat or thermal cut-out; this removes critical protection against fire.