Robot vacuum reports E4 and stops, often near edges or stairs; may be described as cliff sensor error or anti-drop sensor blocked.

Safety first: Turn the robot OFF before cleaning sensors.

• 1. Locate cliff sensors: On the underside of the Yeedi robot, identify the small infrared windows near the front edge (usually 3–4 sensors).
• 2. Clean sensor windows: Use a soft, dry microfiber cloth to gently wipe each sensor window. For stubborn grime, lightly dampen the cloth with water (no chemicals) and wipe again, then dry thoroughly.
• 3. Check for film or stickers: Ensure no protective films, tape, or aftermarket bumpers are covering the sensors.
• 4. Test on different flooring: Place the robot on a non-reflective, light-colored hard floor and start a cleaning cycle. Avoid black carpets or highly reflective tiles during testing.
• 5. Inspect wiring (advanced): If comfortable opening the unit, remove the bottom cover (after removing screws) and check the cliff sensor harness is firmly connected to the main board.
• 6. Replace sensor module if needed: If E4 persists after cleaning and reseating connectors, the cliff sensor assembly may need replacement.

Warning: Do not spray cleaner directly onto sensors; liquid can seep inside and damage electronics.