The ET-4800, like all inkjet printers, has an internal (also called an absorption pad or maintenance box). Its job is to catch ink used during printhead cleaning, power flushes, and priming. Over time, the pad saturates.
When the printer’s internal counter hits a certain number of cleaning cycles or pages, it locks up with a error (often an error code like 0x9A or similar). Epson designs it this way to prevent ink overflow that could damage the printer or leak onto your desk. epson et 4800 waste ink pad replacement
The ET-4800 does not have a user-replaceable waste ink box like some EcoTank models (e.g., ET-2750). The waste pad is inside the printer, buried under the printhead assembly, usually made of absorbent felt. The ET-4800, like all inkjet printers, has an