Code PS0021 / BG0021 / SR0021: ILLEGAL PLANE SELECT
Issue Description & Safety Warning
The Fanuc 0i-D / 0i Mate-D Alarm List has triggered a critical ILLEGAL PLANE SELECT alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Section: CNC alarm list Alarm group: Program/operation, background edit, communication (PS/BG/SR common alarm number) Original alarm number: 0021 The plane selection in structions G17 to G19 are in error. Reprogram so that same 3 basic parallel axes are not specified simultaneously. This alarm is also generated w hen an axis that should not be specified for plane machining is specified, for example, for circular interpolation. T In the 0 i -TD, the helical interpolation option is needed to enable the specificati on of 3 or more axes for the G02/G03 block.
Source: Fanuc B-64305EN/03 Appendix A Alarm List
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc 0i-D / 0i Mate-D Alarm List Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code PS0021 / BG0021 / SR0021 on the 0i-D / 0i Mate-D Alarm List identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Fanuc's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 769 Fanuc 0i-D / 0i Mate-D Alarm List codes.
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