Error 4
Roborock Robot Vacuum
Severity: ModerateWhat Does This Error Mean?
Roborock Error 4 means the cliff sensors detected a drop-off, or one of the cliff sensors has a fault. Cliff sensors are the downward-facing infrared sensors that stop the robot from falling down stairs or off ledges. Cleaning the sensors and moving the robot to flat ground fixes this in most cases.
Affected Models
- Roborock S5
- Roborock S6 MaxV
- Roborock S7
- Roborock Q5 Max
- Roborock E4
- Roborock S8
Common Causes
- Robot is near a stair edge, drop-off, or raised platform edge and the cliff sensors are triggering correctly
- Cliff sensor lenses are dirty — dust, hair, or pet fur covering the downward-facing sensors
- Robot placed on a very dark or black floor surface — dark surfaces absorb the sensor infrared signal, making flat floor look like a drop
- Cliff sensor component has failed after extended use
- Robot started on a surface with a high-gloss finish confusing the infrared sensors
How to Fix It
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Pick up the robot and flip it over. Locate the cliff sensors — small circular or oval lenses on the underside near each corner of the robot.
Roborock models typically have 4 cliff sensors, one near each corner of the underside. They look like small dark windows.
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Wipe each cliff sensor lens with a clean dry cloth or a cotton bud. Even a thin film of dust is enough to give false drop readings.
Do not use wet wipes or liquid cleaners on the sensors — moisture can permanently damage the infrared components.
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Place the robot in the centre of an open area of flat floor, well away from stairs, ledges, and the edge of rugs.
If the robot was near a stair or a raised rug edge when Error 4 appeared, it may have been a correct detection — not a fault.
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If the floor is very dark or black, place a light-coloured mat under the robot's starting area. Dark surfaces absorb the cliff sensor signal and are mistaken for a drop.
This is a known limitation of infrared cliff sensors on all robot vacuum brands — it is not a defect. Roborock's app allows you to reduce cliff sensor sensitivity on some models.
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Press the power button or restart via the Roborock app. If Error 4 clears on flat, light-coloured floor with clean sensors, the cause was environmental.
If Error 4 returns immediately after moving to a clean flat surface, a sensor module has failed.
When to Call a Professional
If the cliff sensors are clean, the robot is on flat light-coloured floor, and Error 4 persists, one of the cliff sensor modules has failed. Contact Roborock support or check for a replacement sensor kit for your model.
Frequently Asked Questions
Can I disable cliff sensors on Roborock?
Some Roborock models allow you to reduce cliff sensor sensitivity in the app settings — useful if you have dark floors. Full disabling is not recommended as it removes the protection against the robot falling down stairs. Check your model's app settings under Advanced.
Error 4 keeps happening in one specific spot — why?
That spot likely has something the cliff sensors react to: a very dark rug, a shiny reflective floor section, or a slight raised edge. Map the area in the Roborock app and set a no-go zone for that spot, or place a small light-coloured mat there.