Roborock · Robot Vacuum Moderate
Error 4 — Cliff sensor dirty or robot on dark surface
The downward-facing cliff sensors detect what they think is a drop-off. Caused by dirty sensors, very dark flooring, or actual stairs.
- Keep using it?
- Yes, with caution
- DIY difficulty
- Easy
- Verified against
- global.roborock.com ↗
How to fix it
- Flip the robot upside down.
- Locate the small black/clear lenses around the front and side edges (cliff sensors).
- Wipe each lens with a dry microfiber cloth, then a slightly damp cloth, then dry again.
- Place the robot on a normal, well-lit floor away from stairs.
- Cover very dark rugs during cleaning or use the app's no-go zones around them.
- Restart cleaning. If error persists on normal floor, contact support.
Why it happens
Typical signs: Voice prompt 'Cliff sensors are dirty, please wipe them' · App shows Error 4 · Robot stops at black rugs or dark floors · Robot stops near stairs
- Dust or smudges on cliff sensor lenses Sensors on the underside collect dust, dulling reflections.
- Very dark or black floor/rug Dark surfaces absorb IR; sensor reads as no floor.
- Reflective/glossy floor Highly reflective surfaces can confuse the IR sensor.
- Robot near an actual drop Working as intended — stop before falling.
- Sensor failure Faulty IR LED or receiver in a cliff sensor.
More Roborock robot vacuum codes
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: global.roborock.com.