The filters can be reset on the Xiaomi air filter, also the small laser particle sensor at the back of the device can be cleaned. Resetting a filter could possibly solve the problem. To do this, press and hold the power button on the front and press the marked button on the back of the air purifier for more than 5 seconds. A sound is played to confirm the reset. However, it is also possible that the particle measurement sensor, which is located under a flap at the back, is dirty or defective. You can usually get these sensors very cheaply from Aliexpress if the warranty has expired.

We are not aware of this error. However, a defect cannot be ruled out.