Freezer displays E21 and the interior light or fan may not turn off when the door is closed.

Safety: Unplug the freezer before working on the door switch or control board.

• 1. Observe light behavior: Close the door slowly and watch through a gap to see if the light goes off just before full closure. If it stays on, the switch is not changing state.
• 2. Inspect door alignment: Check hinges for sagging or misalignment that prevents the door from fully pressing the switch. Adjust hinges if necessary.
• 3. Test door switch: Locate and remove the door switch. Test continuity with a multimeter while pressing the actuator. Replace if it does not switch reliably.
• 4. Check wiring: Inspect the harness from the switch to the control board for shorts to live or neutral that could hold the input in one state.
• 5. Replace faulty parts: Install a new Siemens-compatible door switch or repair wiring as needed.
• 6. Reset and test: Restore power and verify that the light and fan respond correctly to door opening/closing and that E21 is cleared.

Note: If the switch and wiring are good but E21 persists, the main PCB input circuit may be damaged and require replacement.