washer dryer combo OE error

Machine is the LG washer dryer combo. Won’t do a full cycle, first hour in, it says OE error which should mean somethings wrong with the drain. Looked at the website for this error and it told me to check the drain filter. Checked and the drain filter is clean, nothings there. No matter what I tried, the problem persists. Had the whole washer dryer machine replaced, thought nothings gonna be wrong. After an hour in, same problem again. Anyone knows what could be the problem?