DIAGNOSIS The filter reset indicator is separate from the physical filter. You must manually reset the timer after installing a new filter.
FIX With the unit powered ON, press and hold the Filter Reset button (the one with the circular arrow icon) for 3 seconds until the check filter light turns off.
IF THAT DIDN'T WORK You might have installed a third-party or non-genuine Levoit filter. Some aftermarket filters lack the correct RFID tag, so the reset may not work. Try the reset sequence one more time with firm pressure.
HEADS UP The factory reset timer is set for 6-8 months. Even with a new filter, the light will come back on based on time, not actual filter condition, so mark your calendar.