Ordered a new indoor air monitor. PM 2.5 displays "-" most of the time

[redpotato]

I just received a new indoor air monitor. The particulate readings regularly disappear from the dashboard, and the display most often shows “-” for PM 2.5. Occasionally it shows a number.

How can I get a replacement sensor?

Also, the previous indoor unit I ordered came with a clear sticker over the clear display window on the case. The new one didn’t. Was the new one “new,” or was it refurbished? Did the manufacturing change?

[Achim_AirGradient]

We do not ship any refurbished units but stopped adding the display film back onto the device because it is wrapped in the carton sleeve.

The PM issue has been identified as a firmware issue and we have an update available. Please PM me your serial number.

[redpotato]

Thanks for clarifying about the window film. Message sent!