Machine displays ALARM 3; brew boiler does not fill or stops mid-fill, and pump may run continuously or not at all.

Safety first: Turn OFF and unplug the machine. Allow boilers to cool and depressurize. Water and electricity together are hazardous.

Steps to address ALARM 3:

• Check water supply: Ensure the main water supply is open and that any inline filters are not completely blocked.
• Inspect brew boiler level probe: Remove panels to access the brew boiler. The level probe is typically a stainless-steel rod inserted from the top with a single insulated wire. Check that the wire is firmly attached and not corroded.
• Clean the level probe: If accessible, remove the probe from the boiler (after depressurizing and draining to below probe level). Descale the metal rod with food-safe descaler or white vinegar to remove mineral buildup. Rinse thoroughly and reinstall with new gasket if required.
• Check the fill solenoid valve: Locate the brew boiler fill solenoid (often labeled or plumbed directly to the brew boiler). With the machine powered (for qualified users only), listen for a click when the machine attempts to fill. If the coil does not energize or the valve does not pass water, the coil or valve may be faulty.
• Electrical checks (advanced): With power disconnected, measure coil resistance of the fill solenoid and continuity of the level probe wire back to the control board. Replace any open or shorted components.
• If cleaning does not resolve: Replace the brew boiler level probe and/or the brew boiler fill solenoid valve with La Marzocco OEM parts.
• Persistent ALARM 3: If all hardware checks good, the level sensing circuit on the main control board may be defective. Contact a professional technician for board-level diagnosis.