Display shows F1 and the Melitta fully automatic coffee machine will not start a brewing cycle.

Safety first: Unplug the coffee maker from the mains and allow it to cool completely before opening any covers.

Step-by-step checks:

• Power reset: Disconnect power for 5–10 minutes, then reconnect and try again. Sometimes the control board will clear a transient F1 error.
• Check for kinks or blockages: Remove the water tank from your Melitta machine (e.g. Caffeo Solo, Caffeo Barista). Inspect the water intake area and hose leading to the flowmeter for kinks, debris, or heavy limescale. Rinse the tank and clean the intake filter.
• Run a descaling cycle: If the machine will allow it, run a full descaling program using Melitta descaling tablets or a compatible descaler. A partially blocked flowmeter can trigger F1.
• Inspect the flowmeter (advanced): Remove the top cover (usually Torx screws under the water tank and bean hopper). Locate the plastic flowmeter in the cold-water circuit between the tank and pump. Check the wiring connector is fully seated and not corroded. Gently tap the flowmeter to free any stuck rotor, then reassemble and test.
• When to stop: If F1 persists after descaling and checking connections, the flowmeter or main control board is likely defective. Replacement of the flowmeter is usually straightforward; control board replacement should be done by a qualified technician.