after it mops, it goes to the dock but the mop pads don't lift up, so they're dragging on the carpet.

Diagnosis

The Dreame L20 Ultra utilizes a combination of ultrasonic sensors and an infrared carpet detection system located on the underside of the chassis to trigger the mop-lifting mechanism. When the robot fails to lift the mop pads upon returning to the dock or transitioning to a carpeted area, it typically indicates a failure in the "Carpet Detection" logic or a mechanical obstruction in the lifting actuator. If the robot does not perceive a change in surface texture or if the sensor is blinded by debris, it will continue to operate in "Mop Mode," leaving the pads flush against the floor. Another common cause is a misalignment of the mop plate. Because the L20 Ultra features extendable mops, the mechanical arm that lifts the plates can become jammed if the pads are not seated perfectly in their clips or if there is a buildup of dried detergent and grime in the lifting tracks. To confirm this, observe the robot from a side profile during a transition; if you hear the motor attempting to lift (a faint clicking or humming) but the pads stay down, it is a mechanical jam. If there is total silence, it is a sensor or software configuration issue.

How to Fix It

Follow these precise steps to recalibrate the lifting mechanism and clear sensor obstructions:

1. Open the Dreamehome app and navigate to the Robot Settings menu. Locate the Carpet Cleaning section and ensure the "Mop Lift" option is set to "Lift Mop" rather than "Avoid Carpet."
2. Enter the Map Management screen. Check the colored zones on your floor plan. If your carpeted areas are appearing as "General" or "Hard Floor" (usually indicated by a lack of specific carpet hatching), the robot will not trigger the lift. Use the "Edit Map" tool to manually designate these areas as carpets.
3. Power down the robot completely using the physical power button. Flip the unit over and inspect the ultrasonic sensors located near the front bumper. Use a dry, microfiber cloth and a cotton swab dipped in 70% isopropyl alcohol to clean the sensor lenses. Any film of dust or dried mop water can "trick" the robot into thinking it is still on a hard surface.
4. Remove both mop pads and the mop bracket. Inspect the lifting arms for any trapped hair, threads, or debris. Manually push the lifting mechanism up and down to ensure it moves smoothly without resistance.
5. Reinstall the mop pads, ensuring they are snapped firmly into the center of the bracket. If the pads are skewed, they can create friction against the chassis, preventing the motor from achieving a full lift.
6. Run a "Test Clean" in a small area with a high-pile carpet to verify the lift is now triggering.

If That Didn't Work

• Perform a Hard Factory Reset: Press and hold the Reset button (usually located under the top cover near the laser turret) for 10 seconds until the voice prompt confirms the reset. This clears the cache of the carpet detection algorithm which can sometimes become corrupted after a firmware update.
• Adjust the Carpet Detection Sensitivity: In some regional versions of the app, you can toggle the "Carpet Detection" sensitivity. If you have low-pile or "industrial" carpeting, the robot may not detect the texture. Switch the setting to "High Sensitivity" to force the lift on thinner rugs.
• Check for "Mop-Only" Zones: Ensure you haven't accidentally set a "No-Mop Zone" that overlaps with your dock return path. If the robot believes it is in a restricted zone, it may override the standard lifting sequence to prioritize the fastest path back to the base.
• Inspect the Lifting Actuator Gear: If you hear a grinding noise, the internal plastic gear of the lifting motor may be stripped. This requires a hardware replacement of the lift module. Check if the robot is still under warranty before attempting to disassemble the undercarriage.

Heads Up

• Avoid using third-party thick-pile "extra absorbent" mop pads; these often exceed the weight limit of the lifting motor and will cause the pads to sag or fail to lift entirely.
• Clean the dock's mop-washing tray weekly. If the pads are not cleaned thoroughly at the dock, they accumulate heavy grime that increases the weight of the plates, putting strain on the lift mechanism.
• Always ensure the robot is returning to the dock on a hard surface. If the dock is placed directly on a rug, the robot may get confused about its current surface state and fail to trigger the lift sequence correctly.
• Update the firmware immediately when prompted. Dreame frequently releases patches specifically to improve the ultrasonic carpet detection accuracy for the L20 series.