Key Takeaways: Fanuc alarm 414 is a servo alarm indicating a detection error on the affected axis: the digital servo software detected an abnormal condition in the current or feedback loop.
The most common causes, in rough order of likelihood, are a faulty servo amplifier, motor power-line or feedback-cable damage, a failing servo motor, and contamination or loose connections. Diagnose in a strict order, cheapest and safest checks first, and always follow lockout and tagout before touching power components.
On Fanuc controls, alarm 414 reads "SERVO ALARM: n-TH AXIS DETECTION RELATED ERROR" (on Series 16/18/21 the axis is named in the message; on Series 0 the middle digit is the axis, so 414 is axis 1, usually X, 424 is axis 2 and 434 is axis 3). It means the servo system detected abnormal current or an abnormal feedback condition on that axis and shut the axis down to protect the motor and amplifier. The alarm itself does not name the failed component, so the diagnostic work is about isolating which element of the servo loop tripped it.
Check the diagnostic screen first: DGN 200 and DGN 204 (on Series 16/18/21; on Series 0 the details are in DGN 720 to 727, one per axis) break the alarm down into more specific bits such as overcurrent, overload, or feedback disconnect. Record those values before power-cycling, because they narrow the search dramatically.
Repeat servo alarms are rarely random. Track every occurrence with its diagnostic bits in your CMMS so the pattern becomes visible: same axis, same time of shift, same part program.
Pair that history with condition monitoring on motor current and temperature, and put cable inspection on the preventive maintenance schedule for high-flex axes.
Plants running Fabrico also catch the production side automatically: computer-vision-verified OEE records the downtime event and its true duration, and the closed-loop CMMS ties the alarm to the work order that resolved it, which is exactly the failure history that makes MTBF analysis honest.
On Series 0 controls, the middle digit of alarm 4n4 is the axis number: 414 is axis 1 (usually X), 424 is axis 2, 434 is axis 3 and 444 is axis 4. The details sit in diagnosis 720 for axis 1, 721 for axis 2 and so on, so for an X axis 414 you open DGN 720 first.
Bit names vary slightly between controls. For LV, HCA, HVA and DCAL, Fanuc's manual says to check the amplifier LED next.
If the amplifier shows a code instead of its not ready display, write it down before you reset anything. On alpha i servo amplifier modules, 8 is a DC link current alarm, 8., 9. or A. shown with a dot is an IPM alarm, and b, c or d is abnormal motor current. For these current alarms, Fanuc's first test is to disconnect the motor power leads and release the E-Stop: if the alarm returns with the leads off, replace the amplifier; if it does not, check the insulation of the motor and its power cable to ground.
Safety: releasing the E-Stop with the motor leads disconnected is live work for a qualified electrician. Insulate the loose leads and keep clear of the terminals.
Can I just reset alarm 414 and keep running?
You can usually reset it, but if the underlying cause is real it will return, often with more damage. Record the diagnostics and investigate after the first recurrence.
Does alarm 414 always mean the amplifier is dead?
No. Cables and connectors cause a large share of 414 trips and cost far less to fix. Test in order of cost and likelihood.
Is it safe to swap servo amplifiers between axes?
Only between identical models with identical parameter setups, after full power-down and discharge. When in doubt, involve a qualified Fanuc service technician.
How do I stop coolant from causing servo alarms?
Inspect and reseal cable entries and connector boots during scheduled PM, and route or shield high-flex cables away from direct coolant spray.
To see how automatic downtime capture and closed-loop maintenance turn alarms like 414 into fixable patterns instead of recurring surprises, book a demo.
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