Indicator light for dirty water tank full does not come on, and the machine continues to run even when the tank is overflowing.

Safety first: Unplug the unit and empty the dirty tank before inspection.

• Inspect float mechanism: Open the dirty tank and verify that the float is present and moves freely. Replace if missing or damaged.
• Test level switch: With the tank removed, locate the level switch and test it with a multimeter while moving the float. Replace if it does not change state.
• Check wiring to UI: Ensure the sensor wiring is connected to the main PCB and that the PCB connector is secure.
• Check indicator LED: If the sensor works but the light never comes on, the LED or UI board may be faulty and require replacement.

Until repaired, monitor the dirty tank visually and empty it frequently to avoid overflow.