Diagnosis
That’s the ‘Humidistat Fault’ error code. The internal humidity sensor or its circuit has a problem.
How to Fix It
Unplug the unit for one full minute. Plug it back in directly to a wall outlet, not an extension cord. See if 90 clears. If it persists, the main control board is likely bad and needs replacement.
If That Didn't Work
If unplugging doesn't clear it, you cannot fix this yourself. The sensor is integrated into the control board. You need a new main PCB. Call Honeywell support with your serial number.
Heads Up
Do not ignore this code and try to run the unit. It will not dehumidify correctly and could damage the compressor.