Update by user Jun 01, 2021 Nothing needed. Original review posted by user Jun 01, 2021 I had the "e9" error message on my hisense dehumidifier.. I took the filter off, thoroughly cleaned it, used compressed air as well to make certain things were completely clean.... took the back panel off the machine... I located the moisture sensor, used the compressed air on the circuit board, snapped it back into place, made sure that the entire machine was dust / dirt/ contaminate free then reassembled everything everything, machine works fine now User's recommendation: Disassemble and clean the machine thoroughly.