Hi,
Do you mean an ''unable to print error 51''?
Here’s a [https://www.easyink.co.nz/support/brother-mfc-665cw-unable-print-51-error-solved/|link] that may be of some help.
I realize that it is not the same model printer but it still may be worth checking in your model as usually manufacturers don’t change their error codes that often so the error code usually means the same fault symptom but it may not have to be the same problem that caused it to happen