Code SP0027: Position coder disconnected
Issue Description & Safety Warning
The Fanuc Alpha-i Servo Spindle Amplifier has triggered a critical Position coder disconnected 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: 27 Also shown as: SP0027 (15i), SP9027 (30i/31i/32i), SP9027 (0i-D) Action: (2) If this alarm is issued when the cable is moved (a) The connector has a bad contact, or the cable is disconnected. The conductor may be broken. Replace the cable. If coolant has penetrated into the connector, clean the connector. S P Sensor Connected to the frame ground via a cable clamp. Shielded cable αi position coder (3) If this alarm is issued when the motor rotates (a) The shielding of the cable between the sensor and the Spindle Amplifier is faulty. Referring to, "Connection," in "FANUC SERVO AMPLIFIER αi series Descriptions (B-65282EN)," check the shielding of the cable. (b) The signal cable is bundled with the servo motor power lead. If the cable between the sensor and the Spindle Amplifier is bundled with the servo motor power lead, separate them from each other.
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 SP0027 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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