Lexmark 4500-00 Series Service Manual page 85

Controller card error (ROM / NAND)
Indicates a failed controller card assembly. Replace the controller
card.
ASIC failure (957).
Processor failure (956).
Code ROM or NAND failed cyclic redundancy check (CRC)
(955).
4500–E220/E321/E323
SRAM failure (959).
NAND failure (958).
Diagnostic information
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