Robot vacuum refuses to start cleaning and shows E6; app may say 'Cliff sensor error' or 'Drop sensor blocked'.

Safety first: Turn the robot OFF before cleaning sensors to avoid accidental movement.

• Locate cliff sensors: On Philips robot vacuums, cliff sensors are usually located on the underside at the front edge (small dark windows).
• Clean sensor windows: Use a soft, dry microfiber cloth to gently wipe each sensor window. For stubborn dirt, lightly dampen the cloth with water or isopropyl alcohol and wipe again, then dry thoroughly.
• Check for damage: Inspect the plastic windows for cracks or deep scratches that could interfere with the infrared beam.
• Test on a flat surface: Place the robot on a light-colored, flat floor away from edges and start a cleaning cycle. Avoid dark carpets or reflective floors during testing, as they can confuse sensors.
• Reset power: If the error persists, switch the main power OFF for 1–2 minutes, then turn it back ON to reset the control board.
• Persistent E6: If cleaning and resetting do not help, the cliff sensor module or its wiring may be defective. Replacement of the cliff sensor board is recommended via an authorized service center.