While Firmware is usually the best fix, in this case the 402 does not currently have FW known to fix SC899 from most causes.

The only SC899 correction as of yet for the 402 is;
 SC899 may occur when logging out from a machine with the user authenticationenabled. (Fax 2.00.00 correction)

Whereas with most machines, such as the 5002, it was fixed with PCL FW;

 SC899 may occur when logging out from a machine with the user authenticationenabled. (Fax)
 Error SC899 caused by PCL jobs names (@PJL JOBNAME) that contain any number of“%” characters and a banner page. (PCL v1.12- Minimum recc to correct SC899 common occurrences)
 When printing certain documents in Microsoft Word, an SC899 error might occur (PCL)


FW could help, but likely for now your best bet is to clear queues.