Brother FAX-921 - Manual (Page 162)

VI - 11
(12) Maintenance mode
Code 1 Code 2 Causes
E0 01 Failed to detect 1300 Hz signal in burn-in operation.
E0 02 Failed to detect PB signals in burn-in operation.
E0 03 Failed to detect any command from the RS-232C interface in burn-
in operation.
(13) Equipment error
Code 1 Code 2 Causes
FF X X Equipment error (For X X, refer to Subsection 1.1 [ 2 ].)