Display shows E4 and oven stops heating; often associated with cooling fan issues or overheating of control area.

Safety first: Disconnect mains power. Surfaces near the control panel may be hot; allow cooling before working.

• Check ventilation: Ensure that the Clatronic oven has the required clearance around it and that front and rear ventilation slots are not blocked by cabinets or objects.
• Listen for fan operation: When the oven is running (before error appears), you should hear the cooling fan near the control panel. If it is silent, suspect a fan or power issue.
• Access cooling fan: Remove the top cover or rear panel to locate the tangential cooling fan assembly and its wiring.
• Inspect and test: Spin the fan blades by hand; they should rotate freely. Check for grease buildup or obstructions. Measure resistance of the fan motor; an open circuit indicates a failed motor.
• Check overheat thermostat: Locate the small thermal cut-out or thermostat mounted near the control panel or on the top of the oven cavity. Test for continuity at room temperature; an open thermostat will prevent fan operation or trigger E4.
• Replace faulty parts: Replace the cooling fan motor or overheat thermostat with the correct Clatronic spare part. Ensure all wiring is reconnected securely and routed away from hot surfaces.