My Levoit air purifier has started showing a red light and I cannot figure out why it keeps coming back even after cleaning the filters and resetting the unit. The air in my room does not feel heavy and there is no unusual smell so I am confused about what the sensor is picking up.
I took out the pre filter and vacuumed it but the red indicator returned only a few minutes after I switched it back on. I am wondering if the sensor itself is dusty because it does not seem to react the way it used to.
The fan also feels like it changes strength at odd times and I am noticing a slight shift in airflow that was not there earlier which adds to the confusion because I have not changed anything in the room recently.
Has anyone dealt with a red light issue on a Levoit purifier even after cleaning the filters because I would really appreciate advice on what else I should check 
I had this happen with my Levoit model a few months ago and it turned out that the small sensor window on the side had a layer of dust that was very hard to see. It looked clean at first glance but when I wiped it with a dry cotton swab there was a surprising amount of buildup.
Once I cleaned that tiny chamber the red light went away after a few minutes. I think the sensor gets confused when that little square fills up with micro dust so cleaning it carefully might help your unit.
My Levoit stayed on red for almost an entire day and I found out the problem was the activated carbon filter. It looked clean from the outside but there was an odor trapped inside the material that the sensor kept picking up as poor air quality.
Replacing the carbon layer fixed the issue instantly so you might want to check if yours has absorbed something strong like cooking fumes or old smoke.
I want to share my detailed experience because this might help you understand what is happening with your purifier. My Levoit kept showing the red light even though I cleaned every filter layer and even opened the sensor port. Nothing seemed to fix it at first and the sensor reacted slowly to changes in the room.
Then I moved the purifier to a different part of the room and the color shifted back to orange within a few minutes. The corner I had it in had very little airflow and dust kept gathering in that space even though it was not noticeable on the surface.
Airflow matters a lot more than most people realize and Levoit sensors can misread rooms where air becomes stagnant. Try moving your purifier into an open space for a while and see if the sensor behaves differently.
I will try moving it to an open area.
My experience with Levoit purifiers is that humidity can cause the sensor to misread the air. I was running a humidifier in the same room and the moisture mixed with dust and the sensor detected it as poor air quality.
When I turned off the humidifier for about an hour the light eventually changed back from red to blue. If you have any device that releases mist then that might be part of the issue.