Fanuc alarm 998: ROM PARITY
system alarm · Fanuc 0i-D
What it means
A parity error was found in basic ROM at power-up - the contents of the flash/from ROM holding the CNC's basic system software no longer match their checksum. The control cannot trust its own firmware and refuses to start. On FROM-based systems this overlaps alarm 900 (FROM/module mismatch); where both exist, 900 identifies the module and 998 indicates basic ROM corruption.
Likely causes
- Corrupted or failed FROM/ROM device
- Incomplete or interrupted system software load
- ROM socket/contact problem on older boards
Triage note: Recovery usually requires reloading system software from the original media or replacing the FROM module/board.
Need the part urgently?
Send us alarm 998 with your machine details — typical RFQ turnaround is 24–48h.