Roborock robot vacuum reports “Error 27” / “Ultrasonic sensor error” on models with ultrasonic carpet detection.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Sensor face dirty, Sensor cable loose, Ultrasonic transducer failure, Firmware misreading sensor

Safety first: Turn off the robot and place it upside down.

Step-by-step:

Locate ultrasonic sensors: On supported models, these are usually small round or oval windows on the underside near the front.
Clean sensor faces: Wipe gently with a soft, dry cloth to remove dust and film.
Power cycle and update: Restart the robot and check for firmware updates in the app. Apply any updates and retest.

If the error persists: The ultrasonic sensor module may need replacement, which requires opening the robot.

Hard 4/5

Ultrasonic Carpet Sensor Module

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