Code SP0081: Motor sensor one-rotation signal detection error
Issue Description & Safety Warning
The Fanuc Alpha-i Servo Spindle Amplifier has triggered a critical Motor sensor one-rotation signal detection error 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
Amplifier LED display: 81 Also shown as: SP0081 (15i), SP9081 (30i/31i/32i), SP9081 (0i-D) Action: Troubleshooting when this alarm is issued (a) The Spindle Amplifier does not support the SSM. Replace the Spindle Amplifier. (b) The SSM is not mounted or connected. Check the connection of the interface signal cable between JYA4 (Spindle Amplifier) and CX31 (SSM). (c) The interface signal between the Spindle Amplifier and SSM is disconnected. Check the connection of the interface signal cable between JYA4 (Spindle Amplifier) and CX31 (SSM). (d) The SSM is faulty. Replace the SSM.
Source: Fanuc αi Servo/Spindle Amplifier Maintenance Manual (B-65285EN/04) — Part II Troubleshooting
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc Alpha-i Servo Spindle Amplifier Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code SP0081 on the Alpha-i Servo Spindle Amplifier 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: 135 Fanuc Alpha-i Servo Spindle Amplifier codes.
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