Safety first: Unplug the unit and let it cool before internal inspection.

Check basket seal: Ensure the basket drawer is fully inserted and the front face is flush with the housing. A partially open drawer can cause heat loss and H1.
Avoid overloading: Do not overfill the basket; large loads can prevent the unit from reaching set temperature in time.
Verify heater operation: Start a preheat cycle and feel for hot air at the exhaust after 2–3 minutes (without touching metal surfaces). If only lukewarm, inspect the heating element and wiring as described in heater-related entries.
Check sensor placement: Ensure the cabinet temperature sensor is properly mounted and not hanging away from the cooking cavity, which can cause false low readings.
Test heater and sensor: Use a multimeter to verify heater resistance and sensor resistance at room temperature. Replace any component that is out of specification.

If H1 persists with good heater and sensor, the main control PCB may be misregulating power and should be replaced.

Display shows H1 and the unit does not heat properly.

Possible Causes