Diagnosis
The particle sensor is either contaminated or requires recalibration. A persistently red light indicates the sensor is detecting high particulate levels, which may be a false reading.
How to Fix It
Perform a sensor reset. Unplug the unit for 30 minutes. Plug it back in and immediately place it in a known clean environment (like a room with no activity). Let it run on Auto mode for 12-24 hours to establish a new baseline.
If That Didn't Work
The sensor itself may be faulty. As a diagnostic, run the unit in a bathroom after a hot shower. If the light eventually cycles from red to blue as the steam clears, the sensor is functional. If it stays red indefinitely, contact support.
Heads Up
The color indicator is based solely on the laser sensor. It does not measure gases, VOCs, or humidity. High humidity can sometimes cause false red readings by scattering the laser light. Ensure the room humidity is below 60% for an accurate particle reading.