How to Fix / Troubleshooting

Safety first: Immediately stop using the robot near stairs until the issue is resolved.

Clean cliff sensors: Turn OFF the robot and wipe all underside cliff sensor windows with a soft, dry cloth.
Test on different flooring: Try the robot on a lighter-colored, non-reflective floor to see if detection improves.
Improve lighting: Avoid very bright direct sunlight on the sensors, which can interfere with infrared readings.
Use physical barriers: Install physical barriers or magnetic/virtual walls (if supported) at stair edges.
Service if unresolved: If the robot still fails to detect edges, the cliff sensor module may be defective and must be replaced.

Robot vacuum does not detect stairs and has nearly fallen or actually fallen off an edge.

Possible Causes