Troubleshooting / FANUC spindle amplifier alarms

FANUC Spindle Amplifier Alarm Codes

The alarm codes of FANUC alpha i spindle amplifier modules (SPM), with how each one shows on the CNC screen, the likely causes, the first checks in order, and how to log it so it stops repeating.

Where the code shows

On the alpha i spindle amplifier (SPM) an alarm lights the red ALM LED on the front STATUS display and the two-digit 7-segment display shows the alarm code (01, 02, 31, or letter codes such as A, b0, C0). A yellow ERR LED with a number is a sequence or parameter error instead, also shown on CNC diagnosis No. 710 (Series 16i first spindle, 30i, 0i-D) or 1561 (15i).

The CNC screen shows the same alarm as SP9000 plus the code on Series 30i/31i/32i and 0i-D (code 31 = SP9031), as 9031 or 7n31 on Series 16i/18i/20i/21i/0i and Power Mate i (n = spindle number), and as SP0031 on Series 15i.

A few internal codes are reported differently: on the 16i family codes 13, 18, 19 and 20 show as CNC alarm 750 and codes 24, A, A1 and A2 as 749, while 30i and 0i-D show them in the SP12xx range (B-65285EN/04, Part I 4.3.1 and 4.3.3, Part II ch. 2 and 3.4).

Safety first.
The amplifier contains a large electrolytic capacitor and stays charged after power off: before touching it, measure the residual DC link voltage with a tester and confirm the red charge LED is off (B-65285EN/04, p. s-12 and p. 107). Do not touch motor power terminals for at least 20 minutes after the motor power is shut off, because high voltage remains on them (p. s-3).

Follow lockout/tagout and your site's safe-work procedures, and check the manual for your exact model before you act.

Quick lookup

Every code in this table stops the spindle and the machine, so in OEE each one is an availability loss (a breakdown) until the amplifier is reset.

Type a code or a word (overheat, speed, sensor) to filter the list. Click a code for its causes and first checks.

37 codes

SPM codeCNC (30i, 0i-D)Name
01SP9001Motor overheat
02SP9002Excessive speed deviation
03SP9003DC link fuse blown
06SP9006Temperature sensor disconnected
07SP9007Excessive speed
09SP9009Main circuit overload/IPM overheat
10SP9010Low power supply input voltage
12SP9012DC link overcurrent/IPM alarm
13, 18, 19, 20750CPU internal data memory error (13), program sum check error (18), excessive offset of phase U (19) or phase V (20) current detection circuit
15SP9015Output switching/spindle switching alarm
21SP9021Position sensor polarity setting incorrect
22SP9022Spindle amplifier current overload
24749Serial transfer data error
27SP9027Position coder disconnected
29SP9029Short-time overload (Short-period overload on 30i/0i-D tables)
31SP9031Motor lock alarm
34SP9034Parameter data out of the specifiable range
36SP9036Error counter overflow
37SP9037Speed detector parameter error
41SP9041Position coder one-rotation signal detection error
42SP9042Position coder one-rotation signal not detected
47SP9047Position coder signal error
52, 53SP9052, SP9053ITP signal error I / ITP signal error II
54SP9054Current overload alarm
55SP9055Abnormal switching status of power leads
56SP9056Internal cooling fan stopped
66SP9066Communication alarm between spindle and amplifier (16i table: between Spindle Amplifiers)
73SP9073Motor sensor disconnected
81SP9081Motor sensor one-rotation signal detection error
82SP9082Motor sensor one-rotation signal not detected
83SP9083Motor sensor signal error
84SP9084Spindle sensor disconnected
85, 86, 87SP9085 to SP9087Spindle sensor one-rotation signal detection error (85) / not detected (86) / spindle sensor signal error (87)
88SP9088Cooling fan stopped of the radiator
A, A1, A2749Program ROM error
b0SP9110Communication error between amplifiers
C0, C1, C2SP9120, SP9121, SP9122Communication data alarm

Each code: causes and first checks

Spindle alarm 01: Motor overheat

Hits OEE: Availability

What it means: The temperature inside the spindle motor is higher than the specified limit.[1][2]

On the CNC screen: SP9001 (30i/31i/32i, 0i-D); 9001 or 7n01 (16i/18i/20i/21i/0i, Power Mate i); SP0001 (15i)

Likely causes

  • Motor cooling fan stopped, liquid cooling fault or ambient temperature above specification
  • Heavy cutting or acceleration/deceleration so frequent that the average output exceeds the continuous rating
  • With a cold motor: faulty spindle motor feedback cable or wrong motor-specific parameters
  • Faulty control board or faulty internal thermostat in the motor

First checks, in this order

  1. Check whether the motor is really hot: hot points to cooling or load, cold points to the signal path
  2. Check that the spindle motor fan runs and has power; on a liquid-cooled motor check the cooling circuit
  3. Review the cutting conditions and how often the spindle accelerates and decelerates
  4. If the motor is cold, check the feedback cable and the motor-specific parameters against B-65280EN

Spindle alarm 02: Excessive speed deviation

Hits OEE: Availability

What it means: The actual motor speed is far from the commanded speed.[1][2]

On the CNC screen: SP9002 (30i/31i/32i, 0i-D); 9002 or 7n02 (16i/18i/20i/21i/0i, Power Mate i); SP0002 (15i)

Likely causes

  • Acceleration/deceleration time parameter (No. 4082) shorter than the real acceleration time
  • Wrong speed detector parameters
  • Cutting load higher than the motor output
  • Output restriction parameters (No. 4028, 4029) or motor-specific parameters set wrongly

First checks, in this order

  1. Note when it trips: during acceleration or under a heavy cut
  2. During acceleration: set parameter 4082 to the real acceleration/deceleration time plus a margin
  3. Under load: watch the spindle load meter and lighten the cut
  4. Check speed detector and output restriction parameters 4028/4029 against the machine and motor specification

Spindle alarm 03: DC link fuse blown

Hits OEE: Availability

What it means: The DC link fuse inside the spindle amplifier has blown, so the DC link voltage is too low; it is checked when emergency stop is released.[1]

On the CNC screen: SP9003 (30i/31i/32i, 0i-D); 9003 or 7n03 (16i family); SP0003 (15i)

Likely causes

  • Motor power lead short-circuited to ground
  • Motor winding short-circuited to ground
  • Failed IGBT or IPM power module
  • DC link wiring not connected (when it trips at e-stop release or start-up)

First checks, in this order

  1. Note whether it tripped while the spindle was turning or at e-stop release / CNC start-up
  2. With power off and the charge LED off, check the DC link wiring between the power supply and the SPM
  3. Check the motor power leads and the motor winding for a short to ground
  4. If the internal fuse has blown, replace the spindle amplifier

Spindle alarm 06: Temperature sensor disconnected

Hits OEE: Availability

What it means: The motor temperature sensor is abnormal or its cable is broken.[1]

On the CNC screen: SP9006 (30i/31i/32i, 0i-D); 9006 or 7n06 (16i family); SP0006 (15i)

Likely causes

  • Motor-specific parameters set wrongly
  • Faulty motor feedback cable
  • Faulty control board
  • Faulty thermo sensor in the motor

First checks, in this order

  1. Check the motor-specific parameters against B-65280EN
  2. Inspect and if needed replace the motor feedback cable
  3. Replace the control board or spindle amplifier if the cable is good
  4. Replace the motor (thermo sensor) as the last step

Spindle alarm 07: Excessive speed

Hits OEE: Availability

What it means: The motor turned faster than 115% (standard setting) of its maximum allowable speed.[1]

On the CNC screen: SP9007 (30i/31i/32i, 0i-D); 9007 or 7n07 (16i family); SP0007 (15i)

Likely causes

  • In spindle synchronization one motor was switched off (SFR/SRV) and on again, then raced to recover the position error built up while it was off
  • Faulty spindle amplifier

First checks, in this order

  1. Check whether the alarm came during spindle synchronization
  2. If so, change the ladder so the motor is not deactivated and reactivated during synchronization
  3. If not, replace the spindle amplifier

Spindle alarm 09: Main circuit overload/IPM overheat

Hits OEE: Availability

What it means: The heat sink of the SPM main circuit got abnormally hot (on alpha iSP 22, iSP 30HV and larger; smaller models raise alarm 12 for the same cause).[1]

On the CNC screen: SP9009 (30i/31i/32i, 0i-D); 9009 or 7n09 (16i family); SP0009 (15i)

Likely causes

  • Amplifier heat sink fan stopped or ambient temperature too high
  • Heat sink dirty or exposed to coolant
  • Load above the amplifier continuous rating, or too frequent acceleration/deceleration
  • Control board not fully seated, so a connector to the power board is detached

First checks, in this order

  1. Read the load meter: below the continuous rating points to cooling, above it points to how the machine is used
  2. Check the heat sink fan and its supply (connector CX1A/B)
  3. Clean the heat sink with air and keep coolant off it
  4. Push the control board faceplate fully home; if it trips with a cool heat sink, replace the SPM

Spindle alarm 10: Low power supply input voltage

Hits OEE: Availability

What it means: The control power supply voltage has dropped.[1]

On the CNC screen: SP9010 (30i/31i/32i, 0i-D); 9010 or 7n10 (16i family); SP0010 (15i)

Likely causes

  • Faulty control power supply
  • Faulty power cable
  • Faulty power supply module or spindle amplifier

First checks, in this order

  1. Measure the control power supply feeding the power supply module
  2. Check the control power cable between the modules
  3. Replace the power supply module or the spindle amplifier if the supply and cable are good

Spindle alarm 12: DC link overcurrent/IPM alarm

Hits OEE: Availability

What it means: Excessive current flowed in the DC link of the main circuit; on alpha iSP 2.2 to 15 and iSP 5.5HV to 15HV it means the power module (IPM) detected an overload or overcurrent.[1]

On the CNC screen: SP9012 (30i/31i/32i, 0i-D); 9012 or 7n12 (16i family); SP0012 (15i)

Likely causes

  • Motor power leads shorted to each other or to ground
  • Motor winding insulation failure
  • Destroyed power element (IGBT, IPM), often after poor cooling or a dirty heat sink
  • Wrong motor-specific parameters or a bad spindle sensor signal

First checks, in this order

  1. Note whether it trips right at the spindle command or while turning
  2. Check the power leads for phase-to-phase and phase-to-ground shorts, and the motor insulation
  3. Push the control board fully home (a detached board connector can cause it)
  4. Check motor-specific parameters and the spindle sensor waveform; if all good, replace the SPM

Spindle alarm 13, 18, 19, 20: CPU internal data memory error (13), program sum check error (18), excessive offset of phase U (19) or phase V (20) current detection circuit

Hits OEE: Availability

What it means: Internal SPM faults found by its self-checks (19 and 20 are checked at power-on); on the 16i family the CNC reports them as alarm 750 rather than a 9000-series number.[1][4]

On the CNC screen: 750 (16i/18i/20i/21i/0i, Power Mate i); SP12xx (30i/31i/32i, 0i-D); SP098x (15i)

Likely causes

  • Faulty spindle amplifier or its control board
  • Connectors between the power unit and the control board not plugged in properly (19, 20 right after a board swap)

First checks, in this order

  1. Read the code on the SPM display to see which of the four it is
  2. If the control board was just replaced, re-seat the connectors between the power unit and the control board
  3. Otherwise replace the spindle amplifier or its control board

Spindle alarm 15: Output switching/spindle switching alarm

Hits OEE: Availability

What it means: The power lead switching sequence for output (winding) switching or spindle switching did not finish: the check signal (MCFN, MFNHG, RCH or RCHHG) did not change within 1 second of the request (SPSL or RSL).[1]

On the CNC screen: SP9015 (30i/31i/32i, 0i-D); 9015 or 7n15 (16i family); SP0015 (15i)

Likely causes

  • Switching magnetic contactor faulty or without supply
  • Faulty I/O unit or wiring for the contactor check signal
  • Ladder sequence that takes longer than 1 second to switch

First checks, in this order

  1. Check that the switching contactor actually pulls in and has its supply
  2. Check the I/O point and wiring that report the contactor state
  3. Check the ladder so switching completes within 1 second

Spindle alarm 21: Position sensor polarity setting incorrect

Hits OEE: Availability

What it means: The polarity set for the position sensor is wrong.[1]

On the CNC screen: SP9021 (30i/31i/32i, 0i-D); 9021 or 7n21 (16i family); SP0021 (15i)

Likely causes

  • Position sensor polarity parameter (bit 4 of No. 4001) set wrongly
  • Faulty position sensor feedback cable

First checks, in this order

  1. Check bit 4 of parameter 4001
  2. Check the position sensor feedback cable

Spindle alarm 22: Spindle amplifier current overload

Hits OEE: Availability

What it means: A current above the time rating of the spindle amplifier flowed.[1]

On the CNC screen: SP9022 (30i/31i/32i, 0i-D); 9022 or 7n22 (16i family); SP0022 (15i)

Likely causes

  • Very frequent acceleration/deceleration
  • High cutting load

First checks, in this order

  1. Check the spindle load meter during the cycle that trips
  2. Ease the operating conditions: fewer spindle starts and stops or a lighter cut

Spindle alarm 24: Serial transfer data error

Hits OEE: Availability

What it means: The serial data between the CNC and the spindle amplifier contains an error; it also appears when the CNC power is off, which is not a failure.[1]

On the CNC screen: 749 (16i/18i/20i/21i/0i, Power Mate i); SP12xx (30i/31i/32i, 0i-D); SP022x (15i)

Likely causes

  • Electrical noise on the CNC to SPM cable, or cable longer than allowed
  • Communication cable bundled with the motor power lead
  • Faulty cable, optical link adapter or optical cable
  • Faulty spindle amplifier or CNC serial spindle board

First checks, in this order

  1. Make sure the CNC was powered on when the code appeared
  2. Check the cable route: separate the communication cable from motor power leads and check the maximum length
  3. Replace the cable (and optical adapter if fitted)
  4. Then replace the SPM control board or the CNC serial spindle board

Spindle alarm 27: Position coder disconnected

Hits OEE: Availability

What it means: The signal from the alpha i position coder is lost.[1]

On the CNC screen: SP9027 (30i/31i/32i, 0i-D); 9027 or 7n27 (16i family); SP0027 (15i)

Likely causes

  • Wrong sensor setting parameter
  • Broken cable or bad connector contact, including coolant in the connector
  • Poor cable shield grounding or signal cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. Note when it trips: motor off, cable moving, or spindle turning
  2. Motor off: check the sensor parameter and the cable; cable moving: replace the cable and clean coolant out of the connector
  3. Spindle turning: check the shield clamp to frame ground and separate the cable from power leads
  4. If all good, replace the SPM or its control board

Spindle alarm 29: Short-time overload (Short-period overload on 30i/0i-D tables)

Hits OEE: Availability

What it means: An excessive load (standard: load meter 9 V) was applied continuously for a set time (standard: 30 seconds).[1]

On the CNC screen: SP9029 (30i/31i/32i, 0i-D); 9029 or 7n29 (16i family); SP0029 (15i)

Likely causes

  • Cutting load too high
  • Spindle mechanically locked during a very slow move or orientation
  • Wrong sensor parameter, wrong power lead phase order or bad A/B feedback (spindle creeps)
  • Power lead not connected or switching contactor open, or faulty SPM (spindle does not turn)

First checks, in this order

  1. During cutting: check the load meter and review the cut
  2. At a stop: check the ladder does not hold the spindle locked
  3. Turn the spindle by hand and watch motor speed on the CNC diagnosis screen; no reading means cable or sensor
  4. Check the motor power lead and any switching contactor

Spindle alarm 31: Motor lock alarm

Hits OEE: Availability

What it means: The motor did not turn as commanded and has stopped or is turning at a very low speed.[1][2][3]

On the CNC screen: SP9031 (30i/31i/32i, 0i-D); 9031 or 7n31 (16i/18i/20i/21i/0i, Power Mate i); SP0031 (15i)

Likely causes

  • Spindle held by the lock sequence (clamp or orientation) while a speed is commanded
  • Motor power lead open or wrong phase order, or a switching contactor not closed
  • Wrong sensor setting parameter, or motor feedback cable faulty or with phase A/B wired wrongly
  • Faulty spindle amplifier

First checks, in this order

  1. Note whether the motor does not move at all or creeps at very low speed
  2. Not moving: check the ladder is not locking the spindle and the power lead and switching contactor are closed
  3. Creeping: check the sensor parameters and the power lead phase order
  4. Turn the spindle by hand and watch motor speed on the CNC diagnosis screen; no reading means replace the feedback cable or sensor

Spindle alarm 34: Parameter data out of the specifiable range

Hits OEE: Availability

What it means: A spindle parameter was set outside its allowed range.[1]

On the CNC screen: SP9034 (30i/31i/32i, 0i-D); 9034 or 7n34 (16i family); SP0034 (15i)

Likely causes

  • A spindle parameter set or loaded with a value outside its range

First checks, in this order

  1. Connect the spindle check board: it shows AL-34 and F-xxx alternately
  2. Look up F-xxx in B-65280EN to find the matching CNC parameter number
  3. Correct that parameter to a value inside its range

Spindle alarm 36: Error counter overflow

Hits OEE: Availability

What it means: The position error counter overflowed.[1]

On the CNC screen: SP9036 (30i/31i/32i, 0i-D); 9036 or 7n36 (16i family); SP0036 (15i)

Likely causes

  • Gear ratio parameters (No. 4056 to 4059) set too large
  • Position gain parameters (No. 4060 to 4072) too low
  • Motor switched off (SFR/SRV off) during rigid tapping, Cs contour control or spindle synchronization

First checks, in this order

  1. Check the gear ratio parameters 4056 to 4059
  2. If the gear ratio is right, raise the position gain for the mode in use
  3. Check the ladder does not drop SFR/SRV while in a position control mode

Spindle alarm 37: Speed detector parameter error

Hits OEE: Availability

What it means: After an emergency stop the motor accelerated instead of slowing down, or had not stopped when the acceleration/deceleration time (initial 10 seconds) ran out.[1]

On the CNC screen: SP9037 (30i/31i/32i, 0i-D); 9037 or 7n37 (16i family); SP0037 (15i)

Likely causes

  • Speed detector parameter set wrongly
  • Acceleration/deceleration time parameter (No. 4082) shorter than the real stop time

First checks, in this order

  1. Check the speed detector parameters against chapter 1 of B-65280EN
  2. Measure the real stop time and set parameter 4082 to it plus a margin

Spindle alarm 41: Position coder one-rotation signal detection error

Hits OEE: Availability

What it means: The one-rotation signal of the alpha i position coder appears at the wrong position.[1]

On the CNC screen: SP9041 (30i/31i/32i, 0i-D); 9041 or 7n41 (16i family); SP0041 (15i)

Likely causes

  • Wrong sensor setting parameter
  • Faulty position coder (Z signal not once per turn)
  • Poor cable shield or signal cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. Check the sensor setting parameters
  2. Observe the position coder Z signal: it must come once per spindle turn
  3. Check the shield clamp and cable routing
  4. Replace the SPM or its control board if the signal is clean

Spindle alarm 42: Position coder one-rotation signal not detected

Hits OEE: Availability

What it means: The one-rotation signal of the alpha i position coder is not generated.[1]

On the CNC screen: SP9042 (30i/31i/32i, 0i-D); 9042 or 7n42 (16i family); SP0042 (15i)

Likely causes

  • Wrong sensor setting parameter
  • Faulty position coder or connection cable
  • Faulty spindle amplifier

First checks, in this order

  1. Check the sensor setting parameters
  2. Check pin PSD on the spindle check board: no pulse per turn means replace the cable and position coder
  3. Replace the SPM or its control board if the signal is present

Spindle alarm 47: Position coder signal error

Hits OEE: Availability

What it means: The A/B pulse count of the position coder (4096 pulses per spindle turn) is outside the allowed range when checked at each one-rotation signal.[1]

On the CNC screen: SP9047 (30i/31i/32i, 0i-D); 9047 or 7n47 (16i family); SP0047 (15i)

Likely causes

  • Broken conductor in a moving cable or coolant in the connector
  • Wrong sensor setting parameter
  • Poor shield or signal cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. If it trips when the cable moves, replace the cable and clean the connector
  2. Check the sensor setting parameters
  3. Check the shield clamp and separate the cable from power leads
  4. Replace the SPM or its control board

Spindle alarm 52, 53: ITP signal error I / ITP signal error II

Hits OEE: Availability

What it means: The synchronization signal (ITP) in the data exchanged with the CNC stopped.[1]

On the CNC screen: SP9052, SP9053 (30i/31i/32i, 0i-D); 9052/7n52, 9053/7n53 (16i family); SP0052, SP0053 (15i)

Likely causes

  • Faulty spindle amplifier or its control board
  • Faulty CNC board or module for the serial spindle

First checks, in this order

  1. Replace the SPM or its control board
  2. If it persists, replace the CNC serial spindle board or module

Spindle alarm 54: Current overload alarm

Hits OEE: Availability

What it means: A large motor current flowing for a long time was detected.[1]

On the CNC screen: SP9054 (30i/31i/32i, 0i-D); 9054 or 7n54 (16i family); SP0054 (15i)

Likely causes

  • Same causes as alarm 29: heavy cutting, spindle locked, sensor or power lead problems

First checks, in this order

  1. Follow the alarm 29 checks: load meter, spindle lock sequence, speed reading by hand, power lead

Spindle alarm 55: Abnormal switching status of power leads

Hits OEE: Availability

What it means: During spindle or output switching, the switching request (SPSL or RSL) and the power lead check signal (MCFN, MFNHG, RCH or RCHHG) stay mismatched while the motor is active.[1]

On the CNC screen: SP9055 (30i/31i/32i, 0i-D); 9055 or 7n55 (16i family); SP0055 (15i)

Likely causes

  • Faulty switching magnetic contactor or its supply
  • Faulty I/O unit or wiring for the contactor check signal
  • Ladder switches while the motor is active

First checks, in this order

  1. Check the switching contactor and its supply
  2. Check the I/O point and wiring for the contactor state
  3. Change the ladder so switching is never done while the motor is active

Spindle alarm 56: Internal cooling fan stopped

Hits OEE: Availability

What it means: The cooling fan for the SPM control circuit section has stopped.[1]

On the CNC screen: SP9056 (30i/31i/32i, 0i-D); 9056 or 7n56 (16i family); SP0056 (15i)

Likely causes

  • Control board not fully seated
  • Failed internal cooling fan

First checks, in this order

  1. Push the control board faceplate fully home
  2. Replace the internal cooling fan or the spindle amplifier

Spindle alarm 66: Communication alarm between spindle and amplifier (16i table: between Spindle Amplifiers)

Hits OEE: Availability

What it means: An error occurred in the communication on connector JX4.[1]

On the CNC screen: SP9066 (30i/31i/32i, 0i-D); 9066 or 7n66 (16i family); SP0066 (15i)

Likely causes

  • Bad connection on JX4
  • Faulty cable

First checks, in this order

  1. Check the JX4 connection
  2. Replace the cable

Spindle alarm 73: Motor sensor disconnected

Hits OEE: Availability

What it means: The signal from the motor sensor is lost.[1]

On the CNC screen: SP9073 (30i/31i/32i, 0i-D); 9073 or 7n73 (16i family); SP0073 (15i)

Likely causes

  • Wrong sensor setting parameter or sensor not adjusted
  • Broken cable, or coolant in the connector
  • Poor cable shield or signal cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. Note when it trips: motor off, cable moving, or motor turning
  2. Check the sensor parameters and the sensor signal adjustment
  3. Replace the cable if it trips when the cable moves; clean coolant out of the connector
  4. Check the shield and routing, then replace the SPM or its control board

Spindle alarm 81: Motor sensor one-rotation signal detection error

Hits OEE: Availability

What it means: The one-rotation signal of the motor sensor appears at the wrong position.[1]

On the CNC screen: SP9081 (30i/31i/32i, 0i-D); 9081 or 7n81 (16i family); SP0081 (15i)

Likely causes

  • With an external one-rotation signal: wrong gear ratio parameters (No. 4171 to 4174) or slip between spindle and motor
  • Wrong sensor parameter or alpha iMZ / iBZ sensor not adjusted
  • Poor shield or cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. If an external one-rotation signal is used, check parameters 4171 to 4174 and look for slip (not usable with a V-belt)
  2. Check the sensor parameters and adjust the sensor signal
  3. Check the shield and cable routing
  4. Replace the cable and sensor, then the SPM or its control board

Spindle alarm 82: Motor sensor one-rotation signal not detected

Hits OEE: Availability

What it means: The one-rotation signal of the motor sensor is not generated.[1]

On the CNC screen: SP9082 (30i/31i/32i, 0i-D); 9082 or 7n82 (16i family); SP0082 (15i)

Likely causes

  • Wrong sensor setting parameter
  • alpha iMZ / iBZ sensor not adjusted
  • Faulty external one-rotation signal
  • Faulty spindle amplifier

First checks, in this order

  1. Check the sensor parameters
  2. Adjust the sensor; if it cannot be adjusted, replace the cable and sensor
  3. With an external one-rotation signal, check pin EXTSC1 on the spindle check board for one pulse per turn
  4. Replace the SPM or its control board

Spindle alarm 83: Motor sensor signal error

Hits OEE: Availability

What it means: The A/B pulse count of the motor sensor is outside the allowed range when checked at each one-rotation signal.[1]

On the CNC screen: SP9083 (30i/31i/32i, 0i-D); 9083 or 7n83 (16i family); SP0083 (15i)

Likely causes

  • Broken conductor in a moving cable or coolant in the connector
  • Wrong sensor parameter or sensor not adjusted
  • Poor shield or cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. If it trips when the cable moves, replace the cable and clean the connector
  2. Check the sensor parameters and adjust the sensor
  3. Check the shield and cable routing
  4. Replace the SPM or its control board

Spindle alarm 84: Spindle sensor disconnected

Hits OEE: Availability

What it means: The signal from the separate spindle sensor is lost; troubleshoot it like alarm 73.[1]

On the CNC screen: SP9084 (30i/31i/32i, 0i-D); 9084 or 7n84 (16i family); SP0084 (15i)

Likely causes

  • Wrong sensor parameter or sensor not adjusted
  • Broken cable or coolant in the connector
  • Poor shield or cable bundled with a motor power lead
  • Faulty spindle amplifier

First checks, in this order

  1. Follow the alarm 73 checks on the spindle sensor cable and sensor

Spindle alarm 85, 86, 87: Spindle sensor one-rotation signal detection error (85) / not detected (86) / spindle sensor signal error (87)

Hits OEE: Availability

What it means: The same faults as motor sensor alarms 81, 82 and 83, but on the separate spindle sensor.[1]

On the CNC screen: SP9085 to SP9087 (30i/31i/32i, 0i-D); 9085 to 9087 or 7n85 to 7n87 (16i family); SP0085 to SP0087 (15i)

Likely causes

  • Same causes as 81, 82 and 83: parameters, sensor adjustment, cable, shield, SPM

First checks, in this order

  1. 85: follow the alarm 81 checks
  2. 86: follow the alarm 82 checks
  3. 87: follow the alarm 83 checks

Spindle alarm 88: Cooling fan stopped of the radiator

Hits OEE: Availability

What it means: The heat sink cooling fan of the spindle amplifier is not running.[1]

On the CNC screen: SP9088 (30i/31i/32i, 0i-D); 9088 or 7n88 (16i family); SP0088 (15i)

Likely causes

  • Failed heat sink cooling fan

First checks, in this order

  1. Check that the heat sink fan turns
  2. Replace the spindle amplifier heat sink cooling fan

Spindle alarm A, A1, A2: Program ROM error

Hits OEE: Availability

What it means: The SPM control program is not running, or an error was detected while it was running.[1]

On the CNC screen: 749 (16i/18i/20i/21i/0i, Power Mate i); SP12xx (30i/31i/32i, 0i-D)

Likely causes

  • At power-on: wrong software specification or defective control board
  • With the motor active: electrical noise

First checks, in this order

  1. Note whether it appears at power-on or while the motor runs
  2. At power-on: replace the spindle amplifier or its control board
  3. While running: check the grounding and separate the spindle sensor wire from motor power wires

Spindle alarm b0: Communication error between amplifiers

Hits OEE: Availability

What it means: Communication failed between the amplifiers on the same bus (spindle amplifier, servo amplifier and power supply).[1]

On the CNC screen: SP9110 (30i/31i/32i, 0i-D); 9110 or 7n98 (16i family)

Likely causes

  • CXA2A / CXA2B connectors not coupled correctly
  • Defective cable or wrong pin connection
  • Defective spindle amplifier, servo amplifier or power supply

First checks, in this order

  1. Check that each CXA2A is coupled to the next CXA2B
  2. Check the cable pins, or swap the cable
  3. Replace the defective module or its control board

Spindle alarm C0, C1, C2: Communication data alarm

Hits OEE: Availability

What it means: An error occurred in the serial communication data between the CNC and the spindle amplifier.[1]

On the CNC screen: SP9120, SP9121, SP9122 (30i/31i/32i, 0i-D); 9120, 9121, 9122 (16i family)

Likely causes

  • Defective spindle amplifier or its control board
  • Defective CNC board or module for the serial spindle

First checks, in this order

  1. Replace the SPM or its control board
  2. If it persists, replace the CNC serial spindle board or module

Log it, or the same alarm comes back

A spindle amplifier alarm stops the spindle and with it the cut, so in OEE terms each one is a breakdown, and the scrap from an interrupted cut lands in quality too. Log the SPM code with the minutes lost and the part that was in the machine.

  • Reason code: the code plus the machine, for example Spindle amp 31, MC-04, so a spindle that trips weekly stands out from one that tripped once.
  • Loss bucket: a stop that needs a reset, a part or a technician is an availability loss (breakdown). Stops shorter than your micro-stop threshold go to performance (minor stops). The six big losses page shows where each one belongs.
  • What to count: how often each code fires per week and the minutes it costs. Two numbers a week turn "that alarm comes up sometimes" into a ranked list. The MTBF and MTTR calculator and the downtime cost calculator do the math.

The free OEE tracker logs each stop with its reason and turns the week into a downtime Pareto, so the code that costs the most rises to the top.

Alarm 750 (spindle serial link) has its own deep dive on fabrico.io: FANUC alarm 750. An alarm code tells you what the spindle amplifier detected, not what happened at the machine in the seconds before. Fabrico's camera-based OEE software syncs camera video with machine data, so you can replay the moment the spindle stopped next to the alarm.

Frequently asked questions

What does FANUC spindle alarm 31 mean?

On an alpha i spindle amplifier, code 31 is the motor lock alarm: the motor was commanded to turn but stopped or only crept at very low speed. The CNC shows it as SP9031 on 30i and 0i-D, or as 9031 / 7n31 on the 16i/18i/21i/0i family. Check first whether a clamp or orientation sequence is holding the spindle, then the power lead and contactor, the sensor parameters and the motor feedback cable.

What is FANUC spindle alarm 2 (SP9002) excessive speed deviation?

Code 02 means the real motor speed is far from the commanded speed. If it trips while accelerating, the acceleration/deceleration time parameter (4082) is usually shorter than the real time; if it trips in a heavy cut, the load is above the motor output. Watch the spindle load meter and check the speed detector and output restriction parameters (4028, 4029).

How does the code on the spindle amplifier match the alarm number on the CNC screen?

The SPM shows a two-digit code with the red ALM LED, and the CNC builds its number from it: SP9000 plus the code on 30i/31i/32i and 0i-D (01 = SP9001), 9001 or 7n01 on the 16i family (n = spindle number) and SP0001 on 15i. A few internal faults differ: on the 16i family codes 13, 18, 19 and 20 show as alarm 750 and codes 24, A, A1 and A2 as alarm 749.

Can I just reset a spindle amplifier alarm and keep running?

FANUC's manual says to note the alarm number and make sure the original cause has been removed before resetting. Some alarms mean a part must be replaced (for example 03 DC link fuse blown, or 13, 18, 19 and 20), and powering up again without replacing it can damage another component and hide the original cause.

Why do I get spindle alarm 01 motor overheat when the motor is cold?

The manual treats a cold motor as a separate case: suspect the spindle motor feedback cable, wrong motor-specific parameters, the control board or the motor's internal thermostat. A motor that is really hot points instead to cooling (fan, liquid cooling, ambient temperature) or to load and acceleration frequency above the continuous rating.

Sources

Codes and meanings follow the manufacturer documentation below. Wording is ours, simplified for the shop floor; the manual for your exact model and software version wins if it differs.

  1. FANUC AC SERVO MOTOR alpha i series / AC SPINDLE MOTOR alpha i series / SERVO AMPLIFIER alpha i series MAINTENANCE MANUAL B-65285EN/04 (full PDF hosted by distributor MRO Electric)
  2. Fanuc Spindle Amp Alarm Codes for Alpha Series (MRO Electric and Supply)
  3. eMastercam forum: message at VMC (Fadal with FANUC 18i-MB, 2008)
  4. Fanuc Alarm 750 (Spindle Serial Link Start Fault): Causes and Fixes (fabrico.io)

See the moment the spindle stopped

Fabrico, a light MES with computer vision, syncs camera footage with machine and timeline data, so you can replay the exact moment the spindle stopped and review the cause next to its alarm. Cameras also catch short stops and a line that is switched on but not producing, the losses nobody writes down. Machines connect through a PLC, a Fabrico IoT device or an AI camera.

Book a Fabrico demo
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Related: FANUC servo amplifier alarm codes · CNC machine troubleshooting · servo motor · bearing · electric motor

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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

OEE essentials: OEE calculator · What is OEE · How to improve OEE · Six big losses · Availability · TEEP · Cost of downtime · OEE benchmark · Free OEE tracker · Free OEE software · How to track downtime · How to implement OEE · Light MES vs full MES