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FANUC Alarm Code Guide

Find solutions to common Fanuc CNC alarm codes quickly and efficiently.

Servo Alarm
Spindle Alarm
System Alarm
Overtravel Alarm

FANUC Alarms: Quick Guide to Get Back Online​

When your FANUC CNC triggers an alarm, it's trying to tell you something. From simple overtravel to complex servo issues, these codes pinpoint where the problem lies.Our guide cuts through the complexity. We explain the most common alarms—what they mean, why they happen, and how to fix them. Whether you're facing alarm 401 or a stuck overtravel limit, you'll find clear, step-by-step solutions to minimize downtime.​​ You will learn how to:​​

  • Decode any FANUC alarm number.
  • Diagnose faults in servos, spindles, or system memory.
  • Perform basic checks before calling a technician.
  • Identify components that may need adjustment or replacement.

Get the knowledge to solve problems faster and keep your machines running.
FANUC SP9017 Alarm 17: Amplifier ID Data Error Causes and Troubleshooting
FANUC SP9017 means that an error was detected in the spindle amplifier ID data. The CNC displays SP9017, while the spindle amplifier displays alarm 17. FANUC maintenance documentation identifies two main diagnostic directions: the spindle amplifier control printed-circuit board may be loose or incorrectly mounted, or the spindle amplifier may be abnormal. Check that the control board is mounted correctly. If its installation is correct and alarm 17 remains, replace the spindle amplifier according to the applicable FANUC procedure. Alarm location Display Meaning CNC SP9017 / SERIAL SPINDLE ALARM An... Read more...
FANUC SP9016 Alarm 16: Dual Check Safety RAM Error and Troubleshooting
FANUC SP9016 means that the Dual Check Safety function detected an error during a RAM test inside the spindle amplifier CPU. The CNC displays SP9016, while the spindle amplifier displays alarm 16. FANUC Maintenance Manual B-65285EN/04 identifies the spindle amplifier as abnormal and instructs technicians to replace the spindle amplifier. The FANUC Series 30i-A Dual Check Safety Operator's Manual B-64004EN/02 also describes SP9016 as a spindle RAM test error and specifies replacement of the spindle amplifier module. Alarm location Display Meaning CNC SP9016 / SSPA:16 RAM ERROR A spindle amplifier... Read more...
FANUC SP9015 Alarm 15: Spindle Switching Error Causes and Troubleshooting
FANUC SP9015 means that the required sequence was not completed correctly during spindle switching or output switching control. The spindle amplifier displays alarm 15. The alarm is normally issued when a switching request or reference signal changes but the corresponding magnetic-contactor status signal does not change within one second. The main diagnostic areas are the PMC or ladder sequence, magnetic contactor or power-lead switching unit, contactor power supply, feedback wiring, and I/O unit. Alarm location Display Meaning CNC SP9015 Spindle switching or output switching sequence error Spindle amplifier 15 The... Read more...
FANUC SP9014 Alarm 14: Spindle Software Mismatch and Troubleshooting
FANUC SP9014 indicates that the spindle amplifier identification data is not compatible with the series or edition of the spindle control software. The spindle amplifier displays alarm 14. In the FANUC Series 0i-D/0i Mate-D maintenance manual, this condition is described as the use of a spindle amplifier that is not registered in the spindle software program. The stated remedy is to upgrade the spindle software. In the FANUC Servo Amplifier αi Series maintenance manual, alarm 14 is described as inconsistent amplifier ID data, and the stated action is to replace... Read more...
FANUC SP9013 Alarm 13: CPU Internal RAM Error and Troubleshooting
FANUC SP9013 means that the spindle amplifier has detected an error in its CPU internal RAM. The related display on the spindle amplifier is alarm 13. This alarm indicates an abnormality in the spindle amplifier control circuitry. FANUC troubleshooting guidance identifies the spindle amplifier as abnormal and specifies replacement of the spindle amplifier. Depending on the exact amplifier series and applicable maintenance manual, professional testing may identify the control printed-circuit board as the replaceable faulty component. Alarm location Display Meaning CNC SP9013 Spindle amplifier CPU internal RAM error Spindle amplifier... Read more...
FANUC SP9012 Alarm 12: DC Link Overcurrent Causes and Troubleshooting
FANUC SP9012 means that an excessively large current has been detected in the spindle amplifier main circuit. The related spindle amplifier display is alarm 12. Depending on the amplifier series, the alarm may indicate DC link overcurrent or an IPM-detected condition such as excessive load or overcurrent. The correct troubleshooting path depends on when the alarm appears: immediately after power-on, immediately after a spindle rotation command, during normal spindle rotation, or during winding or speed-range switching. Alarm location Display Meaning CNC SP9012 DC link overcurrent / power circuit overcurrent Spindle... Read more...
FANUC SP9011 Alarm 11: DC Link Overvoltage Causes and Troubleshooting
FANUC SP9011 means that the DC link voltage in the main circuit has risen abnormally. The spindle amplifier displays alarm 11, and the common power supply module may simultaneously display alarm 7. This alarm often occurs while a high-inertia spindle motor is decelerating from high speed. If regenerative braking does not operate correctly when motor power is interrupted, the motor may coast instead of stopping immediately, causing the DC link voltage to rise. Alarm location Display Meaning CNC SP9011 DC link overvoltage Spindle amplifier 11 DC link overvoltage Common power... Read more...
FANUC SP9115(S) PS Control Axis Error 2 Alarm: Causes and Troubleshooting Guide
The FANUC SP9115(S) alarm indicates a PS control axis error 2. This alarm occurs when the PS management axis has not been set correctly, or when the spindle is used as the PS management axis but the related parameter setting is incorrect. In many FANUC 30i-B series systems, the common power supply module, also called PS, is controlled by software. Because the PS cannot communicate directly with the CNC, the power supply information must be transferred to the CNC through a servo axis or spindle axis called the PS management axis.... Read more...
FANUC SV5137 FSSB Alarm: Causes and Troubleshooting Guide
The FANUC SV5137 FSSB alarm indicates an FSSB configuration error. This commonly occurs when the connected servo amplifier type or servo axis configuration does not match the FSSB settings in the CNC system. In simple terms, the CNC system has detected a mismatch between the actual servo amplifier connected through the FSSB line and the amplifier or axis configuration registered in the system. If SV5137 appears together with SV5136, SV1067, or other servo/FSSB alarms, troubleshoot those related alarms first. SV5137 may be a secondary alarm caused by communication, amplifier power, or... Read more...
FANUC SV5136 Alarm: FSSB Insufficient Amplifier Number Troubleshooting
FANUC SV5136 alarm means the number of amplifiers recognized by FSSB is less than the number of controlled axes. This usually happens because the axis setting is incorrect, the servo amplifier connection is abnormal, the control power is unstable, the fiber optic cable connection is wrong, or the FSSB compatibility parameter such as 14476 is not set correctly. Before replacing the CNC controller axis card or main board, first check the actual FSSB connection status, servo amplifier power supply, wiring condition, fiber optic connection, amplifier model compatibility, and FSSB-related parameters. What... Read more...
FANUC SV5134 Alarm: FSSB Startup Timeout Troubleshooting
FANUC SV5134 alarm means FSSB did not become ready during startup initialization. The key checks are the FSSB-related parameter settings, P10339#1 when using certain 0i-D system configurations with spindle optical cable connection amplifiers, diagnosis data 3510 / 3511 / 3513, servo amplifier DC24V control voltage, FSSB fiber optic cable connection, fiber ports, and finally the CNC axis card or main board. Before replacing the NC controller axis card or main board, first confirm whether the FSSB connection parameters, servo amplifier control voltage, and fiber optic connection are normal. SV5134 is often... Read more...
FANUC SV1067 Alarm: FSSB Configuration Error Software Troubleshooting
FANUC SV1067 alarm usually means the actual servo amplifier hardware connection does not match the FSSB parameter configuration. The key checks are the amplifier connection status, parameter P1902, servo axis number settings P987/P988, servo axis valid setting P11802#4, FSSB automatic or manual setting, and amplifier/system compatibility. This alarm is often caused by a mismatch between the connected servo amplifier type and the FSSB setting value. Before replacing hardware, first use the FSSB setting screen to confirm which amplifier is recognized and which amplifier or axis is abnormal. What Does FANUC SV1067... Read more...

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