Same problem

I have a same problem. I pretty sure it is related to the humidity sensor. I dropped the water bucket by accident on the dehumidifier ans I have this problem since. If you remove the water bucket, you will find the circuit diagram of the humidifier. It is very helpful when you want to troubleshoot.

To access the sensor, you have to remove the front panel : Remove the water bucket and find the two screws holding the front panel. Remove it and gently praye the front panel. Be carefull, there is two clip on the top wich are really easy to break. The sensor is screwed in the top right, under the cover.
The thermistor for the room temperature is on the same board, the E2 code will be displayed if you have a problem with it. E3 code is related to the termistor located on a pipe on the right side of the dehumidifier.