E-12, E-13 and E-14 — the maintenance box
Good news, because this one you can fix yourself. The maintenance box is a replaceable cartridge that catches waste ink, unlike the internal pads, and it's sold as a normal consumable. E-12 means it's full and needs replacing. E-13 means it's missing or not seated properly. E-14 means the printer can't recognise it, so reseat it first and replace it if that doesn't take. Order the box by its part number for your specific model, since they aren't interchangeable across ranges.