Light 3 (eco) flashes when the bottom tray has filled with water. The machine reverts to pump out only mode. The most common leak source is around the salt filler cap, because you can inadvertently loosen the ring that holds the salt reservoir onto the machine (sealing it). You'll need to tighten this ring nut first. Then remove the water from the tray. This involves removing the side panels and using a cloth or wet and dry hoover.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix dishwashers.