Why the robot vacuum cleaner Xiaomi Mi stopped washing the floors: a full analysis of the causes and solutions

If your Xiaomi Mi robot vacuum cleaner suddenly refuses to clean floors but is vacuuming normally, the problem is not the general breakdown, but the specific module, and most often, owners will find that the device either completely ignores the wet cleaning function, or it will issue an error like "Moping module locked" or "No water in the tank" even though the tank is full, and 80% of the time it is not mechanical damage, but software failures, blockages or improper settings.

Take your time to bring the machine to the service: in this article, we will analyze all possible causes, from the banal (dried dirt in the tubes) to the complex (damage to the flow sensor), and you will learn how to reset the robot to the factory if the problem is in the firmware, and what to do if the Mi Home does not see the cleaning module. For convenience, we have compiled a diagnostic checklist and a table with error codes, which will save you hours to find a solution.

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1. Checking the obvious: water, filters and mechanical locks

Start with the basics -- often the problem is solved in 5 minutes. The first thing you need to do is disconnect the water tank and make sure there's liquid in it. Even if you think the tank is full, check the float sensor (a small plastic tongue inside). If it's stuck in the top position, the robot "thinks" there's no water, and blocks the moping.

The second is to look at the tubes and injectors. In the Xiaomi Mi Robot Vacuum-Mop 2 Pro and Mi Mop 2 Lite, water is fed through thin channels that are easily clogged with lime plaque or dust, blow them or rinse them under a stream of warm water. If the nozzles clog, the robot will drive around the room, but the floor will remain dry.

The third is a rough filter (the net before the pump) that needs to be washed after every 3-4 cleaning cycle, and if the filter is clogged, the pump cannot pump water, and the system emits an error.

• 💧 Check the water level: the sensor is triggered at a level below 100 ml.
• 🔧 Clean the nozzles: Use a toothpick or compressed air.
• 🧽 Wash the filter: soak it in acetic solution (1:1) for 10 minutes.
• 🔄 Reboot the robot: Remove the battery for 30 seconds.

⚠️ Warning: Never use metal objects to clean, they will damage the silicone seals of the tubes. If the water does not go after washing, the problem may be a faulty pump (see section 5).

2. Mi Home app errors: settings and firmware failures

If the robot vacuums but ignores the floor wash command, it could be the software that's to blame.

1. whether the moping function is manually enabled (sometimes it gets lost after updating).

Is the "Vacuum Only" tick in the cleaning settings?

3. whether the firmware is relevant - outdated versions often glitch with the water module.

To update the software:

1. Open Mi Home → Choose your robot.
2. Go to Settings → Update firmware.
3. If a new version is available, click Update and wait until it is completed (the robot will restart).

If the update doesn’t help, try resetting to factory settings:

Press and hold the Home + Spot Cleaning buttons on the robot body for 10 seconds until you hear the beep.

3. Clogging or breakage of the pump (pump) of water supply

The pump is the heart of the moping system, and if it's clogged or broken, the robot will ride with a dry cloth.

- The robot makes a buzzing sound, but the water doesn't flow.

The application appears the error "Pump blocked" (Error 12 or Error 18).

- After cleaning, the cloth remains dry, although the tank is full.

To diagnose the pump:

1. Remove the water tank and disconnect the feed tube.
2. Turn on the mapping mode and listen: if the pump is buzzing, but the water is not coming, it is clogged. If the silence, the pump is burned.

For cleaning:

1. Blow the tube with compressed air (you can use a bicycle pump).
2. Wash the pump with distilled water (not tap water!).
3. If you see rust or plaque inside, replace the pump (Article for Mi Robot Vacuum-Mop P: MDZ-21-EC).

⚠️ Note: If the pump burns, it will cost 30-50% to replace the new robot, in which case it makes sense to consider buying a new model, for example, Xiaomi Mi Robot Vacuum-Mop 2 Ultra with a self-cleaning station.

Check the voltage on the pump contacts (should be 5V)

Examine the tubes for cracks

Try pumping water manually (by disconnecting the hose)

Make sure the filter does not block the flow.-->

4. Damage to sensors: water level, flow or humidity

Xiaomi Mi robots are equipped with three key sensors for moping:

1. Water level sensor (float) - determines whether there is liquid in the tank.

2. Stream Sensor - monitors whether water passes through the pump.

3. rag humidity sensor (in models with drying function).

If one of them breaks down, the robot will either refuse to wash the floor or will do it incorrectly (for example, pouring water continuously).

In Xiaomi Mi Mop 2 Pro models, the flow sensor often fails due to lime water. If you use tap water, be sure to add special softening tablets (for example, Xiaomi Mi Water Softener).

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To extend the life of the sensors, after each cleaning, drain the water from the tank and dry the robot for 1-2 hours with the lid open.

5. Problems with the rag or fastening of the moping module

Sometimes the problem lies not in the electronics, but in the mechanical part.

The rag is incorrectly installed (does not fit tightly to the base).

- The moping module's attachment is loose or broken.

- The rag is worn (lost or torn).

In Xiaomi Mi Robot Vacuum-Mop models, the rag is attached to the Velcros, and if they're clogged with dust, the module won't lock, and the robot can't wash properly.

1. Remove the cloth and wash the Velcros underwater.
2. Check the spring-loaded mounting mechanism - it must securely press the cloth to the floor.
3. If the cloth is broken, replace it with the original one (Article: MOP-CL01).

Another common problem is vibration moping (in models with stain-cleaning function). If the vibrating motor is burned, the robot will just ride with a wet cloth without wiping the dirt. You can check this by turning on the Deep Mopping mode in the app: if there is no vibration, the motor is defective.

6. firmware failures or conflict with Xiaomi servers

Sometimes the robot stops washing floors because of software glitches that are not mechanical.

- After the firmware update, the sensor calibration flew off.

Mi Home is not synced to the cloud (the robot does not receive commands).

- Regional settings have been lost (in some countries the moping function is disabled by default).

How to fix it:

1. Reconnect the robot to Wi-Fi: Settings → Wi-Fi → Forget the network → Connect again
2. Change region in Mi Home: Profile → Region → Select China (all functions are unlocked there)
3. Reset via ADB (for advanced users): adb shell am start -n com.xiaomi.mihome/.activity.DeviceResetActivity

If the robot gives you an Error 24 error, try logging out of your Mi Account and logging in again, which solves the sync problem in 60 percent of cases.

7. When you can not do without service: critical breakdowns

If you’ve tried all of the above, but the robot still doesn’t clean floors, the problem may be:

- Burned control board (often after a voltage surge).

- Damaged connector of the moping module (oxidation or break of contacts).

Wear gears in the water supply mechanism (typical for models over 3 years old).

Signs of serious breakdown:

The robot does not respond to the moping commands from either the app or the buttons.

When you turn on the cleaning mode, you hear cracking or grinding.

- On the case, traces of plastic melting are visible (especially near the power connector).

In this case, it is not recommended to repair the robot yourself - without special equipment, you risk permanently disabling it. mi.com/service).

⚠️ Warning: If the robot is warranty, do not open the case yourself - this will cancel warranty obligations. In Russia and CIS countries, the official warranty for Xiaomi robot vacuum cleaners is 12 months.

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Before contacting the service, make a backup cleaning card in Mi Home (Settings → Map → Export) so as not to configure the robot again.

FAQ: Frequent questions about moping malfunctions