Display shows E04 and the machine will not brew; pump does not start or stops quickly.

Safety: Unplug the machine before opening covers. Water and electricity are present together inside.

• Check water supply: Ensure the water reservoir is full and properly seated, or that the plumbed‑in line is open and has adequate pressure.
• Bleed air: Run a manual water delivery (hot water tap or brew without coffee) if possible to purge air from the system. Airlocks can prevent the flowmeter from registering pulses.
• Inspect the flowmeter: Locate the plastic flowmeter (often near the inlet from the tank or mains). Check for kinks in hoses and signs of scale. Remove the flowmeter and open it carefully; clean the internal turbine with food‑safe descaler and rinse thoroughly.
• Check wiring: Verify the flowmeter connector is firmly attached to the main control board and that wires are not pinched or broken.
• Replace flowmeter: If cleaning does not restore operation and E04 persists, replace the flowmeter assembly with a compatible Rancilio part.

Tip: After replacing or cleaning the flowmeter, run several rinse cycles to confirm stable operation.