Display shows E04, solution pump does not run and no water is sprayed

Safety first: Disconnect power and relieve any pressure in the solution line before disconnecting hoses.

• Check solution tank level: Ensure the clean solution tank is filled with water/chemical mix to the correct level. Some Nilfisk models will trigger E04 if the tank is empty.
• Inspect and clean solution filter: Locate the inline solution filter or strainer (often at the tank outlet or before the pump). Remove, rinse thoroughly, and reinstall.
• Bleed air from pump: Refill the tank, reconnect hoses, and with the machine powered, briefly trigger the solution valve while the brush is raised (if allowed by the model). This can purge air from the pump. Do not run the pump dry for more than a few seconds.
• Check for kinks or blockages: Inspect solution hoses from tank to pump and from pump to spray jets. Straighten kinks and clear any mineral buildup in the jets using a soft brush or descaling solution.
• Test pump electrically: With power disconnected, measure resistance across the pump motor terminals. An open circuit indicates a failed pump. Replace the Nilfisk solution pump assembly if defective.