Fixed: Error C7990 "machine failure call service" Kyocera Ecosys M2540dw.

Learn how to fix error C7990 "machine failure call service" on Kyocera Ecosys M2540dw. This error indicates that the waste toner container or drum unit is full. In some cases, this error message caused by a faulty waste toner sensor. You might be able to resolve it by simply restarting your printer. If it doesn&help, you will need to replace the entire drum unit. Unfortunately, on this particular model, the waste toner container is integrated into the drum unit and it doesn&have a service plug or opening to empty waste toner. You will need to replace the entire drum unit. It is a very simple process. You will need to open the front cover, remove the toner cartridge and processing unit, and then remove the drum unit. Install the new drum unit and put everything back together in the reverse order of removal.