U3 means the control board thinks it filled too quick. There is a High pressure & a Low pressure water setting. If it is set wrong you will get the U3 fault. Open the drawer and place a finger on the programme selection button and the Eco button at the same time. Hold it for 5 seconds until it beeps. LCD screen should now have a red back light and either HP or LP on the screen. If it shows LP change it to HP by pressing the start/pause button once. The press power off button on front which will lock in the HP setting. Try a wash cycle.
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