How to Fix Error Code 004-321 on Fuji Xerox DocuPrint C525 A Printer?

To address the issue with your Fuji Xerox DocuPrint C525 A printer, start by checking the photo sensor located on the left end of the crossbar, which becomes visible when you remove the drum cartridge (IBT assembly). It’s possible that the sensor is fouled with toner, so cleaning it might help. Additionally, slowly rotate the drum drive cog of the drum cartridge until you can see the silver reflector on the left edge of the transfer belt. Make sure this reflector is also clean, as toner buildup can cause issues. Be cautious not to touch the belt or drum with your fingers, as this can lead to further problems. If cleaning the photo sensor and the silver reflector doesn’t resolve the issue, the problem might be related to a connector on the PWBA circuit board, which is located under the left end cover. Sometimes, these connectors can become loose, so unplugging and then re-plugging them can help restore functionality. If you notice that the rubber transfer belt has shifted sideways, this can lead to error code 004-321. In that case, you can try to realign it. Position the drum cartridge so that the blue drum is facing you, then use your thumbs to gently roll the drum up. This should help move the silver square on the belt into the correct position. If there’s excess toner covering the silver square, it may be hard to see, so make sure to wipe it clean with a lint-free cloth. If you’ve tried all these steps and the issue persists, it’s possible that the drum itself is faulty, especially if the belt has moved to one side. In that case, replacing the drum might be necessary. If you’re still under warranty, consider having it serviced.