Code SP0041: Position coder one-rotation signal detection error
Issue Description & Safety Warning
The Fanuc Alpha-i Servo Spindle Amplifier has triggered a critical Position coder 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: 41 Also shown as: SP0041 (15i), SP9041 (30i/31i/32i), SP9041 (0i-D) Action: (c) The shielding of the cable between the sensor and Spindle Amplifier is faulty. Referring to "Connection," in "FANUC SERVO AMPLIFIER αi series Descriptions (B-65282EN)," check the shielding of the cable. (d) The signal cable is bundled with the servo motor power lead. If the cable between the sensor and Spindle Amplifier is bundled with the servo motor power lead, separate them from each other. (e) The Spindle Amplifier is faulty. Replace the Spindle Amplifier or Spindle Amplifier control printed circuit board.
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 SP0041 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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