Ascaso coffee machine shows E4 and the pump does not run; no water is drawn from the tank.

Basic checks:

• Verify water tank: Ensure the tank is full, properly seated, and that any magnetic float or level probe is moving freely. Clean the tank and float if there is scale or debris.
• Check tank valve: On models with a bottom valve, confirm that the valve opens when the tank is inserted. Clean or replace the tank valve seal if it sticks.

Advanced checks (unplug machine first):

• Inspect level sensor: Some Ascaso models use a conductivity probe or magnetic reed switch. Check for broken wires or loose connectors. Clean the probe with a non-abrasive pad to remove scale.
• Check the flowmeter: Locate the plastic flowmeter (usually between pump and boiler). Remove the inlet and outlet hoses and inspect the turbine for blockage. Rinse with clean water and reassemble, ensuring correct flow direction.
• Test sensor signals: With a multimeter, verify continuity of the level sensor and that the flowmeter pulses when water is manually blown through (for experienced users only).
• Replace faulty parts: If the level sensor or flowmeter is not functioning, replace it with the correct Ascaso part. If sensors are good but E4 persists, the control board input may be defective and require replacement.

Note: After repairs, prime the pump by running water through the group and steam wand to remove air from the system.