When F0 or FO displays on your Philips Air Purifier, please clean the pre-filter and reset the cleaning time. Find out how to reset pre-filter cleaning time for your model below:
AC121x, AC138x
After cleaning the pre-filter, please touch and hold the Child Lock button for three seconds to reset the pre-filter cleaning time.
AC272x, AC382x, AC492x
After cleaning the pre-filter or descaling the humidification wick, please touch and hold Timer/Reset button for three seconds to reset the cleaning time for the pre-filter or wick.
AC288x, AC2891, AC325x, AC455x, AC407x, AC565x, AC5660, AC667x, AC868x
After cleaning the pre-filter, please touch and hold the reset button for three seconds to reset the pre-filter cleaning time.
If after cleaning and resetting the pre-filter timer the F0 (FO) is still displayed, please contact us through philips.com/contact for further assistance.





