Display shows E4 and the coffee maker will not start; on some Avanti espresso-style models, the pump does not run and no water flows.

Safety first: Unplug the unit before removing covers or hoses. Hot water and steam can cause burns; ensure the machine is cool.

• Check reservoir and intake: Make sure the water reservoir is full and properly seated. Inspect the intake screen at the bottom of the reservoir for debris; rinse and clean if clogged.
• Clear air lock: Fill the reservoir, then remove and reinsert it several times to help purge air. On some models, starting a brew cycle with the brew head open for a few seconds can help draw water into the pump (consult your manual).
• Descale the hydraulic path: Run a descaling cycle with a vinegar solution (1:1 vinegar to water) to dissolve mineral deposits in the pump and tubing. Follow with multiple fresh-water cycles.
• Listen for pump operation: During a brew attempt, listen for a humming or buzzing from the pump area. A loud hum with no water flow suggests a blockage or seized pump; silence suggests a failed pump or control board.
• Inspect hoses (advanced): With the unit unplugged and base removed, check silicone hoses to and from the pump for kinks, pinches, or scale blockages. Straighten or replace as needed.

If E4 persists and the pump does not run or move water after descaling and clearing blockages, the pump assembly or flow sensor likely needs replacement.