Bialetti digital espresso machine shows E04 and stops brewing; water may leak into the drip tray instead of the cup.

Safety first: Unplug the machine and allow pressure to dissipate before opening the brew head or removing the portafilter/capsule holder.

• Clean the brew head: Remove the portafilter or capsule adapter. Unscrew and clean the metal shower screen and gasket area with a soft brush and hot water to remove coffee oils and fines.
• Backflush (if applicable): For models with a 3-way valve and backflush capability, use a blind filter and a backflush detergent to clean internal brew passages.
• Descale the brew circuit: Run a descaling cycle to dissolve scale in the brew valve and thermoblock. Follow Bialetti's recommended descaler and procedure.
• Inspect the portafilter or capsule holder: Ensure the filter basket holes are not blocked. Soak in hot water with espresso cleaner and scrub. For capsule machines, clean the piercing needle and outlet spout with a fine brush or needle (with the machine unplugged).
• Check the overpressure valve (advanced): Access the OPV on the pump outlet. If it is stuck closed or heavily scaled, it can cause E04. Clean or replace the OPV as needed.

If E04 continues after thorough cleaning and descaling, the internal brew valve or OPV may be defective and require replacement.