Code DS0309: APC ALARM: REF RETURN IMPOSSIBLE
Issue Description & Safety Warning
The Fanuc 0i-D / 0i Mate-D Alarm List has triggered a critical APC ALARM: REF RETURN IMPOSSIBLE 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: Other alarms (DS alarm) An attempt was made to set the zero point for the absolute position detector by MDI operation when it was impossible to set the zero point. Rotate the motor manually at least one turn, and set the zero position of the absolute position detector after turning the CNC and servo amplifier off and then on again.
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 DS0309 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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