Robot vacuum reports 'Error 20' / voice prompt 'Error 20: Water tank error' on mopping-capable Xiaomi models.

Safety first: Turn off the robot and remove the water tank. Do not operate the robot with leaks present.

• 1. Reseat the water tank:
  • Remove and reinsert the water tank until it clicks.
  • Ensure the mop pad frame is correctly attached.
• 2. Inspect tank contacts and magnets:
  • Clean the metal contacts on the tank and robot with a dry cloth.
  • Check for missing magnets or broken tabs on the tank.
• 3. Check for leaks:
  • Fill the tank and observe for drips or cracks; replace if leaking.
• 4. Test pump operation:
  • Start a mopping cycle and listen for the pump clicking or humming.
  • If no sound and the tank is detected, the pump or its driver may be faulty.
• 5. Replacement:
  • Replace the water tank assembly if detection or pump issues persist.
  • If a new tank does not resolve the error, the robot's water tank detection circuit may be faulty and require mainboard repair.