Possible Cause #1:

There is dust on the particle sensor lens

Solution:

Clean the particle sensor lens according to the user manual instructions (page 15)

 

Possible Cause #2:

Sensor sensitivity is too high (Pollution level is continuously high)

Solution:

Adjust the sensor sensitivity to a less sensitive level or standard level (user manual page 14)

 

Possible Cause #3:

Sensor sensitivity is too low (Pollution level is continuously low)

Solution:

Adjust the sensor sensitivity to a more sensitive level or standard level (user manual page 14)