Digital Bialetti espresso machine will not start a brew cycle; display shows E01 immediately after power-on.

Safety first: Unplug the coffee maker before removing covers or reaching inside. Do not work on the unit while it is connected to mains power.

• Check water tank seating: Remove the water reservoir completely and reinsert it firmly until it clicks or feels fully engaged. Many Bialetti digital models use a small switch or magnetic reed sensor that must be precisely aligned.
• Fill and reseat the tank: Ensure the tank is filled above the minimum line. Low water can prevent the sensor from detecting the tank.
• Clean the float and sensor area: If your reservoir has a floating magnet, verify it moves freely. Rinse the tank with warm water and a bit of mild dish soap, then flush thoroughly. Remove any scale or coffee residue around the sensor window on the machine body.
• Inspect for cracks or warping: A cracked or deformed tank may not press the microswitch correctly. If the tank does not sit flat or wobbles, replacement is recommended.
• Test the switch (advanced): With the unit unplugged, access the water tank switch or reed sensor behind the tank area (usually held by a couple of screws). Check that the actuator moves freely. If you have a multimeter and experience, test continuity when the switch is pressed. Replace the sensor assembly if it does not change state.

If E01 persists after cleaning and reseating, the water tank sensor assembly is likely faulty and should be replaced or serviced by a technician.