For the last couple of weeks this washer has been running most of the way through the cycle and then stopping and displaying one of these error codes: F01, F21, F27 or F33. I click stop and run a drain and spin without a 2nd rinse. Sometimes it does this, sometimes I just get another error code. When I unplug it for a while sometimes it runs fine, other times the same thing again.
The hose is not plugged. I cleaned the drain pump filter which wasn't bad. I checked the wire harness connections to the drain pump, pressure switch, water inlet valve and CCU. All seem okay.
I checked the continuity of the drain pump, inlet valve solenoids (hot and cold), pressure switch and motor. All were as published in what I could find online. Pins 4 and 5 on the motor was 113 ohms instead of 120 (close enough?).
I ran the diagnostic test twice; same result both times. Only F21 and F33 showed in the history even though I've had F01 and F27 as well. The first 3 parts of the diagnostic test ran as expected. For the next 3, the washer did as it was supposed to but the LED flashed instead of being on continuously like for the first 3 parts. I don't know if this is significant or not? For the last part of the diagnostic test the LED for Handwash lit up instead of Silk/Delicate as expected and instead of the drum rotating and ramping up to max. speed it didn't do anything.
This last part suggests to me that maybe the MCU is shot. On the other hand none of the error codes suggest that so maybe it's the CCU.
How can I narrow this down? Or is it something entirely different?