How to fix an SC400 error on a Ricoh Aficio SP C430DN printer

On a Ricoh C430DN printer, an SC400 error is often caused by a dirty image density (ID) sensor.  You can clean this sensor yourself, rather than pay a technician to come out and do it.  A dirty ID sensor can also cause other problems, such as color misalignment issues.

The ID sensor on this printer is actually a set of five sensors, located on the ID sensor board.  The ID sensor board is located inside the front door of the C430DN. You can see a picture of it in the service manual, on pages 4-48 and 4-49. (If you don't have the service manual, you can probably find it online -- such as on lfncopiadoras.com -- but always be careful when viewing or downloading documents from unfamiliar sites.) The manual shows you the procedure for removing the ID sensor board; you don't need to do all of those steps just to clean it.  Follow the steps shown until you are comfortable seeing or reaching the ID sensors so you can clean them.

If you can get to the sensors, you can wipe them down with a dry, lint-free cloth.  You can use a tiny bit of alcohol to clean them, but make sure you wipe off every last drop.  If you can't physically reach the sensors, use canned air to clean them.  Be sure to clean all five sensors.  Don't use an oil rag or a cleaning wipe to clean the sensors, as these can leave a residue.

Often, cleaning the ID sensors and rebooting the printer will resolve an SC400 error.  If the problem persists, however, it may be time to call a technician to diagnose it.  You may need to replace the ID sensor board, or you could have a problem with the transfer belt unit or another internal component.