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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 SV0475 Alarm: Excess Error During Movement (Servo DSP) and Troubleshooting
FANUC SV0475 means that the servo processor detected a moving-axis position deviation greater than the applicable limit in parameter No.1838 or No.1841. This alarm belongs to the position-error monitoring function of FANUC Dual Check Safety. The CNC may display SV0475 EXCESS ERROR (MOVE:SV) together with the affected axis. Alarm item Meaning CNC alarm SV0475 EXCESS ERROR (MOVE:SV) Detection side Servo CPU / servo DSP Detection state The axis is moving Monitored value Servo following error, also called position deviation Applicable limit No.1838 when safety monitoring is requested; No.1841 when it... Read more...
FANUC SV0474 Alarm: Excess Error at Stop (Servo DSP) and Troubleshooting
FANUC SV0474 means that the servo processor detected a stopped-axis position deviation greater than the limit specified by parameter No.1839 or No.1842. This alarm belongs to the position-error monitoring function of FANUC Dual Check Safety. The alarm message may appear as SV0474 EXCESS ERROR (STOP:SV), with the affected axis identified on the CNC screen. Alarm item Meaning CNC alarm SV0474 EXCESS ERROR (STOP:SV) Detection side Servo CPU / servo DSP Detection state The axis is judged to be stopped Monitored value Servo following error, also called position deviation Applicable limit... Read more...
FANUC SV0607 Alarm: Converter Main Power Open Phase and Troubleshooting
FANUC SV0607 means that the common power-supply or converter module detected an abnormal input power condition caused by an open phase. On the applicable FANUC αiPS or αiPSR power-supply module, the status display shows alarm E. FANUC Maintenance Manual B-65285EN/04 directs technicians to check the input power-supply voltage first. If the voltage is normal, the next official action is to check the power connections. This makes the incoming three-phase supply, upstream switching devices, terminals, and power wiring the primary diagnostic path. Alarm location Display Meaning CNC SV0607 / converter main... Read more...
FANUC SV0606 Alarm: Power-Supply Radiator Cooling Fan Failure and Troubleshooting
FANUC SV0606 means that the cooling fan for the external radiator or cooling fin of the common power-supply module has stopped. In the FANUC αi Series maintenance manual, the CNC displays SV0606, while the applicable αiPS power-supply module displays alarm A. FANUC's official procedure is to confirm that the radiator cooling fan rotates normally and replace it if defective. The manual also identifies a stopped unit stirring fan on certain power-supply models and an incorrectly seated control printed-circuit board or internal board connector as possible causes. Alarm location Display Meaning... Read more...
FANUC SV0605 Alarm: Excessive Regenerative Power and Troubleshooting
FANUC SV0605 means that the regenerative power returned by the motors was excessive over a short period. On systems using the applicable αiPSR regenerative power-supply module, the power-supply display shows alarm code 8. FANUC Maintenance Manual B-65285EN/04 identifies two principal fault paths: the regenerative resistance is insufficient for the application, or the regenerative circuit inside the PSMR/αiPSR is abnormal. The official actions are to review the regenerative-resistor specification and replace the regenerative power-supply module if its internal regenerative circuit has failed. Alarm location Display Meaning CNC SV0605 / CNV. EX.... Read more...
FANUC SV0601 Alarm: Inverter Radiator Fan Failure and Troubleshooting
FANUC SV0601 means that the radiator or heat-sink cooling fan on the servo amplifier inverter has stopped, or—on certain amplifier series—its speed has fallen below the monitored level. The CNC commonly displays SV0601 INV. RADIATOR FAN FAILURE, while the servo amplifier displays alarm F. FANUC's official troubleshooting order is to inspect the fan for foreign material, confirm that the control printed-circuit board is fully seated where applicable, check the fan connector, replace the fan, and finally replace the servo amplifier if the alarm remains. Alarm location Display Meaning CNC SV0601... Read more...
FANUC SV0604 Alarm: Amplifier Communication Error and Troubleshooting
FANUC SV0604 means that communication between the servo amplifier and the related amplifier or common power-supply module is abnormal. On the applicable FANUC amplifier, the status display shows P. For the FANUC Servo Amplifier αi Series covered by Maintenance Manual B-65285EN/04, the official procedure is to check the CXA2A/CXA2B connector and cable, replace the control printed-circuit board if required, and then replace the servo amplifier if the alarm remains. Connector designations can differ on other series; for example, some βi systems use CXA2A/CXA2C. Alarm location Display Meaning CNC SV0604 /... Read more...
FANUC SV0603 Alarm: Inverter IPM Overheat and Troubleshooting
FANUC SV0603 means that the Intelligent Power Module (IPM) inside the servo amplifier inverter detected an overheat condition. On applicable multi-axis FANUC servo amplifiers, the amplifier display commonly shows 8., 9., or A., identifying the L-, M-, or N-axis inverter channel. FANUC's official troubleshooting sequence is to confirm that the control printed-circuit board is fully seated, check that the heat-sink cooling fan is running, verify that the motor is used at or below its continuous rating, inspect the electrical cabinet's cooling capacity, confirm that the ambient temperature is not excessive,... Read more...
FANUC SV0602 Alarm: Servo Amplifier Inverter Overheat and Troubleshooting
FANUC SV0602 means that the inverter section of the servo amplifier has overheated. On the applicable FANUC servo amplifier, the status display commonly shows alarm 6, while the CNC displays SV0602, often described as INV. OVERHEAT or SV RADIATOR OVERHEAT. FANUC's official troubleshooting sequence is to confirm that the servo motor is operating at or below its continuous rating, verify the cooling capacity of the electrical cabinet, check that the ambient temperature is not excessive, confirm that the control printed-circuit board is fully seated where applicable, and replace the servo... Read more...
FANUC SV0600 Alarm: Inverter DC Link Overcurrent and Troubleshooting
FANUC SV0600 means that excessive current was detected in the DC link of a servo amplifier inverter. The most likely causes are a short circuit or ground fault in the motor power cable, a short circuit or ground fault in the servo motor windings, or a defective servo amplifier. On the applicable multi-axis FANUC servo amplifiers, the amplifier display identifies the affected inverter channel as 8, 9, or A. The CNC displays SV0600, usually together with the affected axis information. Alarm location Display Meaning CNC SV0600 / INV. DC LINK... Read more...
FANUC SP9133 Alarm D3: Serial Sensor Data Transfer Error and Troubleshooting
FANUC SP9133 means that the spindle amplifier detected abnormal serial data received from the serial spindle sensor. The CNC displays SP9133, while the spindle amplifier displays d3 or D3, depending on the display convention used by the machine. FANUC Maintenance Manual B-65285EN/04 explains that the serial data received by the spindle amplifier was corrupted by noise. Its specified troubleshooting direction is to inspect the shielding of the cable between the serial sensor and spindle amplifier. Alarm location Display Meaning CNC SP9133 / Serial Spindle Alarm Serial sensor data was not... Read more...
FANUC SP9132 Alarm D2: Serial Sensor Data Error and Troubleshooting
FANUC SP9132 means that communication between the serial spindle sensor and the spindle amplifier has been interrupted. The CNC displays SP9132, while the spindle amplifier displays d2 or D2, depending on the display convention used by the machine. FANUC Maintenance Manual B-65285EN/04 describes alarm d2 as a disconnected communication path between the serial sensor and spindle amplifier. The possible causes depend on whether the alarm occurs during initial commissioning or appears on a machine that previously operated normally. Alarm location Display Meaning CNC SP9132 / Serial Spindle Alarm Serial sensor... Read more...

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