Display shows F4 and the Melitta coffee machine stops mid-cycle or will not start brewing.

Safety first: Disconnect from mains before removing the brew group or opening covers.

Basic steps:

• Remove and clean brew group: Open the service door, remove the brew unit, and rinse it thoroughly under lukewarm water. Let it dry and lightly lubricate moving joints with food-safe silicone grease approved for coffee machines.
• Check for obstructions: Inspect the brew chamber area for loose coffee grounds, broken plastic pieces, or foreign objects blocking movement.
• Reinsert correctly: Ensure the brew group is reinserted in the correct position until it clicks. Misalignment can cause F4.

Advanced checks:

• With covers removed, observe the brew group drive motor and gears while the machine attempts to start (use extreme caution around live parts).
• Listen for grinding or clicking that indicates stripped gears.
• Test the brew group position microswitch or Hall sensor for proper operation.

If cleaning and lubrication do not resolve the issue, the brew group drive motor or gear set may need replacement. If the position sensor is faulty, replace it according to Melitta service instructions.