Display shows E09, recovery tank full icon flashes and suction stops even when tank is empty

Safety first: Unplug the machine and remove the recovery tank before inspection.

• Inspect float assembly: Locate the float shutoff in the recovery tank or lid. Ensure the float moves freely up and down. Clean off lint, foam residue, and debris.
• Check lid seating: Make sure the recovery tank lid is correctly seated and latched. Misalignment can falsely trigger the full sensor.
• Clean sensor area: If the sensor is optical or conductivity‑based, clean the sensor window or probes with a soft cloth and mild detergent.
• Test float switch: If accessible, disconnect the float switch and test continuity while moving the float. Replace the Nilfisk recovery tank level switch if it remains open or closed in all positions.
• Bypass test (for diagnosis only): Temporarily bridge the sensor connector to simulate an empty tank and see if E09 clears. Do this only briefly and never operate the machine long‑term with the safety defeated. If the error clears, replace the sensor.