Fanuc alarm 976: L-BUS ERROR
system alarm · Fanuc 0i-D
What it means
A bus error was detected on the local bus - the high-speed bus connecting the main CPU board to its directly-coupled sections. The CNC halts immediately because instruction/data fetches can no longer be trusted. Distinguish this from 974 (FANUC bus, inter-board) and 975 (motherboard internal bus).
Likely causes
- Main CPU board bus circuitry defective
- Poorly seated board creating intermittent bus contact
- Severe electrical noise event
Triage note: Sibling codes: 974 F-BUS ERROR and 975 BUS ERROR are documented separately.
Need the part urgently?
Send us alarm 976 with your machine details — typical RFQ turnaround is 24–48h.