What does 4E mean on HP printer?

I'm curious, can you tell me what the term "4E" refers to when it appears on an HP printer? Does it signify a specific error code, a mode of operation, or perhaps a certain setting that needs to be adjusted? As a cryptocurrency and finance professional, I may not be directly familiar with the intricacies of printer terminology, but I'm always eager to learn more about how technology can impact various industries, including those related to printing and documentation. Can you enlighten me on the meaning of 4E on an HP printer?