Troubleshooting / Yaskawa Motoman alarms

Yaskawa Motoman Alarm Codes

The alarm codes that stop Yaskawa Motoman robot cells most often on DX100, DX200 and YRC1000 controllers: what each one means, the likely causes, the first checks in order, and how to log it so the same stop stops coming back.

How Motoman alarms show on the pendant

When an alarm occurs the robot stops at once and the ALARM window opens on the programming pendant with the 4 digit alarm number, the alarm name and, for many alarms, sub data such as the axis that tripped [S L U R B T], a sub code, the control group or the servo board number.

Move the cursor onto the alarm and press SELECT to open the detail window, which shows the content, the cause and the measure for that alarm. The first digit is the alarm level: alarms 0xxx to 3xxx are major alarms, servo power is cut automatically, RESET does not clear them, and you must switch the main power off, remove the cause and switch the power back on.

Alarms 4xxx to 9xxx are minor alarms, and once the cause is fixed you clear them with RESET on the ALARM window or with the external alarm reset input.

Errors are a different thing: they show on the message line, do not stop a running robot, and are cleared with CANCEL. The pendant keeps the last 100 alarms of each type under SYSTEM INFO, then ALARM HISTORY, and that history can be saved to a USB drive through the external memory SAVE menu under SYSTEM DATA.

Safety first.
Before anyone works near the arm, press an emergency stop on the controller door, the pendant or the external device and check that the SERVO ON lamp goes out, and make sure nobody is inside the robot's operating range before you switch power on, jog the robot or run it.

If you must enter the fenced area, put your own lockout device on the safety fence, post a sign so nobody closes it, face the robot and keep a clear escape route. Switch the controller power off before opening its doors, and wait at least 5 minutes before touching power units, amplifiers or converters.

Yaskawa also asks you to confirm with a tester that no charge remains before checking servo wiring. Follow lockout/tagout and your site's safe-work procedures, and check the manual for your exact model before you act.

Quick lookup

Every alarm in this table cuts servo power or stops the robot, so in OEE each one is an availability loss until the cell is reset.

Type an alarm number or a word (collision, absolute data, battery, brake) to filter the list. A few numbers mean different things on DX200 and YRC1000, so each meaning has its own row; click a number for its causes and first checks.

47 codes

CodeName
0020CPU COMMUNICATION ERROR
0021COMMUNICATION ERROR(SERVO)
0060COMMUNICATION ERROR(I/O MODULE)
0100COMMUNICATION ERROR(SV#1)
0790MEMORY BATTERY WEAK
0999PCI-e COMMUNICATION ERROR (YRC1000)
0999NMI ERROR (DX200)
1105SYSTEM ERROR(SERVO)
1200HIGH TEMPERATURE(IN CNTL BOX)
1325COMMUNICATION ERROR(ENCODER)
1326DEFECTIVE ENCODER ABSOLUTE DATA
1327ENCODER OVER SPEED
1328DEFECTIVE ENCODER
1335ENCODER NOT RESET
1341SERVO OVERRUN ERROR
1365GROUND FAULT
1547CURRENT FEEDBACK ERROR
1681BRAKE POWER ERROR
1683DC 24V POWER SUPPLY FAILURE(SV)
1684INSTANT POWER FAILURE(TRQ)(SV)
1694GROUND FAULT(BRAKE LINE)
4100OVERRUN IN ROBOT AXIS (DX100)
4740M-SAF OVERRUN DETECT (DX200, YRC1000)
4107OUT OF RANGE (ABSO DATA)
4109DC 24V POWER SUPPLY FAILURE(I/O)
4110SHOCK SENSOR ACTION
4117BRAKE POWER ERROR
4301CONTACTOR ERROR
4304CONVERTER INPUT POWER ERROR
4307SERVO ON DEFECTIVE SPEED
4311ENCODER BACK-UP ERROR
4312ENCODER BATTERY ERROR
4315COLLISION DETECT
4320OVERLOAD(CONTINUE)
4321OVERLOAD(MOMENT)
4326OVER SPEED
4328SERVO TRACKING ERROR
4336OPEN PHASE(CONVERTER)
4337OVERCURRENT(AMP)
4414EXCESSIVE SEGMENT (LOW/HIGH)
4416PULSE LIMIT(MIN./MAX.)
4418CUBE LIMIT(MIN./MAX.)
4669DETECT BRAKE SLIP
4676BROKEN FAN FUSE
4741M-SAF PPESP SIG. ERROR
4746M-SAF SAFETY FENCE SIG. ERROR
4973POSITION ERROR(COLLISION DETECT)

Each code: causes and first checks

Alarm 0020: CPU COMMUNICATION ERROR

Hits OEE: Availability

What it means: At power on the controller checks that every CPU board it expects is answering, and one of them did not respond. The sub code tells you which board.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 0020 CPU COMMUNICATION ERROR; board names differ (YCP21 on DX200, YCP01 on DX100). Major alarm, power cycle to clear.

Likely causes

  • Main CPU board (ACP01 on YRC1000) not fully seated or failed
  • Optional CPU board (ACP02) failed or set up wrong in maintenance mode
  • Interface board (AIF01 on YRC1000) failed
  • Software operation error at start up

First checks, in this order

  1. Switch the power off and back on
  2. Check that the CPU and option boards named by the sub code are fully inserted
  3. Check the optional board settings in maintenance mode
  4. Save CMOS.BIN, then replace the board named by the sub code, or call Yaskawa if it repeats

Alarm 0021: COMMUNICATION ERROR(SERVO)

Hits OEE: Availability

What it means: The main CPU could not pass commands to a servo control board, so the arm cannot be driven. The sub code points at the servo board.[1][2][3]

Also on: YRC1000 sub code 50 means servo board #1, 51 board #2 and so on. DX200 and DX100 list 0021 COMMUNICATION ERROR(SERVO) with their own board names.

Likely causes

  • Control group settings or the servo board rotary switch set wrong
  • Loose or damaged servo communication cables (CN509, CN515/516, CN111, CN155 on YRC1000)
  • Servo board (SDCA01 on YRC1000) failure
  • Interface board (AIF01) failure

First checks, in this order

  1. Switch the power off and back on
  2. Check control group settings in maintenance mode and the servo board rotary switch
  3. Reseat the servo communication cables listed for the sub code
  4. Save CMOS.BIN, then replace the servo board, then the interface board

Alarm 0060: COMMUNICATION ERROR(I/O MODULE)

Hits OEE: Availability

What it means: The controller remembers which I/O modules are connected and checks them at power on, and one of them could not be found.[1][2][3]

Also on: YRC1000 sub code shows the serial bus number. DX200 and DX100 also list 0060 COMMUNICATION ERROR (I/O MODULE).

Likely causes

  • Module slot rotary switch or I/O module settings in maintenance mode set wrong
  • Loose I/O communication cable, missing terminator on the last station, or no 24V on the module
  • I/O module failure
  • Safety or interface board (ASF01 or AIF01 on YRC1000) failure

First checks, in this order

  1. Switch the power off and back on
  2. Check the module rotary switch and the I/O module settings in maintenance mode
  3. Check the communication cable, the terminator and the 24V supply of the module
  4. Save CMOS.BIN, then replace the module, then the board

Alarm 0100: COMMUNICATION ERROR(SV#1)

Hits OEE: Availability

What it means: The serial link between the main CPU board and the first servo board failed its watchdog check, so the servo cannot be controlled.[1][2][3]

Also on: YRC1000 uses 0100 to 0107 for servo boards SV#1 to SV#8. DX200 and DX100 name 0100 COMMUNICATION ERROR (EAXA#1), the same check on their EAXA servo board.

Likely causes

  • Control group settings or servo board rotary switch set wrong
  • Loose servo board cables (CN509, CN515, CN111, CN157 on YRC1000)
  • Servo board (SDCA01) failure
  • Interface board (AIF01) or main CPU board (ACP01) failure

First checks, in this order

  1. Switch the power off and back on
  2. Check control group settings and the servo board rotary switch
  3. Reseat the servo board cables
  4. Save CMOS.BIN, then replace the servo board, the interface board and the CPU board in that order

Alarm 0790: MEMORY BATTERY WEAK

Hits OEE: Availability

What it means: The battery that backs up the controller memory is flat or unplugged, which puts job and setting data at risk.[1][2][3]

Also on: YRC1000 (AIF01 board), DX200 (YIF01 board), DX100 (YIF board). The DX200 manual notes the controller can start in maintenance mode showing this alarm.

Likely causes

  • Battery plug not seated on CN110/BAT of the interface board
  • Battery worn out
  • Other board fault (Yaskawa then asks for a CMOS.BIN backup)

First checks, in this order

  1. Check that the battery is plugged into CN110/BAT
  2. Replace the battery following the battery replacement chapter of the maintenance manual
  3. If it comes back, save CMOS.BIN and contact Yaskawa

Alarm 0999: PCI-e COMMUNICATION ERROR (YRC1000)

Hits OEE: Availability

What it means: On a YRC1000 the controller found a fault on the PCI-e link to an optional CPU board or to the safety board.[1]

Also on: YRC1000 only. On DX200, 0999 is NMI ERROR (next row). 0999 is not in the DX100 alarm list.

Likely causes

  • Optional ACP02 board failure (sub codes 20 to 27)
  • Safety board ASF01 failure (sub codes 30 and up)
  • Interface board AIF01 failure
  • Loose cables between the safety board, servo board, interface board and power supply (CN207, CN509, CN515, CN111, CN155)

First checks, in this order

  1. Switch the power off and back on
  2. For sub codes 30 and up, reseat the cables listed for that ASF01 board
  3. Save CMOS.BIN, then replace the board named by the sub code
  4. If it still repeats, contact Yaskawa

Alarm 0999: NMI ERROR (DX200)

Hits OEE: Availability

What it means: On a DX200, 0999 is a CPU interrupt fault that Yaskawa puts down to a software operation error inside the controller.[2]

Also on: DX200. On YRC1000 the same number means PCI-e COMMUNICATION ERROR. Not in the DX100 list.

Likely causes

  • Software operation error in the controller
  • Other fault not named in the manual, which Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Switch the power off and back on
  2. If it returns, save CMOS.BIN in maintenance mode
  3. Contact Yaskawa with what the robot was doing when it happened

Alarm 1105: SYSTEM ERROR(SERVO)

Hits OEE: Availability

What it means: An internal control check on the servo board failed. The sub code tells which check, from a bad command to a function setting that does not suit the robot type.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1105 SYSTEM ERROR (SERVO).

Likely causes

  • Servo board failure (SDCA01 on YRC1000, EAXA21 on DX200)
  • Main CPU board or interface board failure
  • Software operation error
  • Motor gun or servo float parameters that do not match the robot type (sub codes 31 and 32 on YRC1000)

First checks, in this order

  1. Write down the sub code, then switch the power off and back on
  2. For a parameter sub code, check the parameter Yaskawa names for it
  3. Save CMOS.BIN, then replace the servo board
  4. If it repeats, contact Yaskawa with the sub code

Alarm 1200: HIGH TEMPERATURE(IN CNTL BOX)

Hits OEE: Availability

What it means: The temperature sensor in the controller's power supply unit tripped because the inside of the cabinet got too hot.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1200 HIGH TEMPERATURE (IN CNTL BOX).

Likely causes

  • Heat build up inside the controller cabinet
  • Power supply unit failure (CPS01K on YRC1000, YPS21 on DX200, YPS on DX100)
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Check whether the OHT LED on the power supply unit is lit
  2. Let the inside of the controller cool down, then switch the power off and back on
  3. If it comes back, replace the power supply unit
  4. Still there: save CMOS.BIN and contact Yaskawa

Alarm 1325: COMMUNICATION ERROR(ENCODER)

Hits OEE: Availability

What it means: The controller lost serial contact with the motor encoder on the axis shown, so it no longer knows that axis position. Encoders are chained, so the axes after the broken link also show.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1325. The YRC1000 maintenance manual has its own procedure for alarms 1325 and 1377.

Likely causes

  • Damaged or loose cable in the arm between encoder and multi-port connector, or a bad manipulator cable
  • Encoder failure
  • Multi-port connector failure
  • Short or ground fault on the +5V encoder supply line inside the arm
  • Servo board failure

First checks, in this order

  1. Check the cables of the first axis in the sub code and of the axis before it
  2. Switch the power off and back on, then check the manipulator cable and the encoder connector on the servo board (CN508 on YRC1000)
  3. If the first chained axis is shown, check the +5V line for a ground fault or short
  4. Replace the encoder, then the encoder one position before, then the multi-port connector, then the servo board

Alarm 1326: DEFECTIVE ENCODER ABSOLUTE DATA

Hits OEE: Availability

What it means: At power on the controller read bad absolute position data from the encoder of the axis shown.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1326. Sub code shows the axis.

Likely causes

  • Loose or damaged cable between encoders or at the servo board
  • Encoder failure
  • Servo board failure

First checks, in this order

  1. Switch the power off and back on
  2. Check the cables between encoders and the servo board encoder connectors
  3. Replace the encoder of the axis shown
  4. Save CMOS.BIN, then replace the servo board

Alarm 1327: ENCODER OVER SPEED

Hits OEE: Availability

What it means: An axis moved while the controller was powering up, for example an arm sinking under its own weight, and the encoder saw a speed of 400 rpm or more.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1327. Sub code shows the axis.

Likely causes

  • An axis dropped during power on because of brake slip or a brake control relay fault
  • Weak or disconnected encoder battery, seen together with an encoder backup error
  • Loose encoder cable
  • Encoder failure

First checks, in this order

  1. Switch the power off and back on
  2. Before switching servo power off, park the robot in a pose where no axis can drop
  3. If an encoder backup error shows too, replace the battery of that axis
  4. Check for brake slip and the brake control relay, then the encoder cables; replace the motor (encoder) if it repeats

Alarm 1328: DEFECTIVE ENCODER

Hits OEE: Availability

What it means: The encoder on the axis shown reports an error in its own internal data.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1328. Sub code shows the axis.

Likely causes

  • Loose or damaged encoder cable
  • Encoder failure
  • Servo board failure

First checks, in this order

  1. Switch the power off and back on
  2. Check the cables between encoders and the servo board encoder connectors
  3. Replace the encoder
  4. Save CMOS.BIN, then replace the servo board

Alarm 1335: ENCODER NOT RESET

Hits OEE: Availability

What it means: The reset that should clear an encoder backup error did not finish, so the position of that axis is still not trusted.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1335. Sub code shows the axis.

Likely causes

  • Encoder battery failure
  • Encoder failure
  • Servo board failure
  • Connection failure (listed on DX100)

First checks, in this order

  1. Replace the encoder battery
  2. Switch the power off and back on
  3. Replace the encoder of the axis shown
  4. Save CMOS.BIN, then replace the servo board

Alarm 1341: SERVO OVERRUN ERROR

Hits OEE: Availability

What it means: The servo side saw the overrun signal, which means an axis ran onto its overrun limit switch or the overrun circuit opened. This is a major alarm.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1341. See also 4100 (DX100) and 4740 (DX200, YRC1000) for the minor overrun alarms.

Likely causes

  • The robot moved past its motion range and pressed the overrun limit switch
  • Break or loose wire in the overrun circuit
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Check whether the robot is pressing the overrun limit switch
  2. Check the overrun line wiring
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 1365: GROUND FAULT

Hits OEE: Availability

What it means: The converter found a ground fault on a motor power line. It cannot tell which axis, but a 4337 at the same time or in the alarm history points to it.[1][2][3]

Also on: YRC1000 and DX200 list 1365 GROUND FAULT as a major alarm. DX100 (and DX200) also list 4335 GROUND FAULT as a minor alarm for a ground fault seen by the servo side.

Likely causes

  • Damaged or wet power cable, often on an external or travel axis sharing the same converter
  • Ground fault in a regenerative resistor
  • Poor ground wiring of the incoming supply
  • Motor, amplifier or converter failure
  • Servo board or power unit failure

First checks, in this order

  1. Look in the alarm history for a 4337 to find the axis
  2. Check motor power cables for damage and water, including external axes
  3. Check the regenerative resistors for a ground fault
  4. Check the voltage between each incoming phase and ground; Yaskawa says review the grounding if the phases differ by more than 100V
  5. Replace the motor, inverter board or converter that is shorted

Alarm 1547: CURRENT FEEDBACK ERROR

Hits OEE: Availability

What it means: Too much current flowed in a motor. The sub data shows the alarm content and the physical axis.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 1547 CURRENT FEEDBACK ERROR.

Likely causes

  • Ground fault or short between the U, V and W motor power wires
  • Loose motor power or servo board connectors
  • Load too heavy or the job too aggressive at that step (speed, acceleration)
  • Amplifier or motor failure, including a fault on an external axis amplifier
  • Servo board failure

First checks, in this order

  1. Check the U, V and W motor wires for ground faults and shorts
  2. Check the servo board, inverter board and motor power connectors
  3. Check the load, then lower the speed, adjust ACC and DEC or change to MOVJ at that step, watching for new interference
  4. Replace the amplifier, then the external axis amplifier, the motor and the servo board

Alarm 1681: BRAKE POWER ERROR

Hits OEE: Availability

What it means: The supply that powers the motor brakes failed, so the controller shut servo power off.[1][2][3]

Also on: YRC1000 names it BRAKE POWER ERROR; DX200 and DX100 name it BRAKE POWER ERROR(SV).

Likely causes

  • Loose brake supply connectors (CN543, CN544 on the servo board, CN153 on the power unit for YRC1000)
  • Short circuit or ground fault on the brake or 24V lines
  • Servo board failure
  • Brake board failure (YBK board on DX100)

First checks, in this order

  1. Switch the power off and back on
  2. Check the brake supply connectors
  3. Check the brake and 24V wiring for shorts and ground faults
  4. Save CMOS.BIN, then replace the servo board (brake board on DX100)

Alarm 1683: DC 24V POWER SUPPLY FAILURE(SV)

Hits OEE: Availability

What it means: The 24V output of the controller's power supply unit is out of range.[1][2][3]

Also on: YRC1000 (CPS01K unit), DX200, DX100 (YPS unit) all list 1683.

Likely causes

  • Short circuit or ground fault on a +24V line
  • Short or ground fault in the brake wiring or the backside duct fan, if it happens at servo on
  • Power supply unit failure

First checks, in this order

  1. Switch the power off and back on
  2. Check the +24V lines from the power supply unit (CN154 to CN157 on YRC1000) for shorts and ground faults
  3. If it trips at servo on, check the brake wiring and the backside duct fan
  4. Replace the power supply unit

Alarm 1684: INSTANT POWER FAILURE(TRQ)(SV)

Hits OEE: Availability

What it means: A short dip in the incoming power happened and motor torque saturated, so the servo tripped.[1][2][3]

Also on: YRC1000 and DX200 name it INSTANT POWER FAILURE(TRQ)(SV); DX100 lists 1684 INSTANT POWER FAILURE. 1685 is the version for a dip that lasts longer than a set time.

Likely causes

  • Incoming supply voltage dropping
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Check whether the incoming supply voltage is dropping
  2. Switch the power off and back on
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 1694: GROUND FAULT(BRAKE LINE)

Hits OEE: Availability

What it means: The brake wiring of the axis shown is shorted or grounded.[1][2]

Also on: YRC1000 and DX200. Not found in the DX100 alarm list.

Likely causes

  • Short circuit or ground fault in the brake wiring
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Switch the power off and back on
  2. Check the brake connection of that axis for a short or ground fault
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4100: OVERRUN IN ROBOT AXIS (DX100)

Hits OEE: Availability

What it means: On a DX100 the robot overrun limit switch tripped, which normally means an axis ran past its hard limit.[3][4]

Also on: DX100 only; 4101 OVERRUN IN EXTERNAL AXIS covers external axes. DX200 and YRC1000 report a tripped overrun switch as 4740 M-SAF OVERRUN DETECT.

Likely causes

  • An axis actually hit the overrun limit switch
  • Loose connection at the YPU unit CN203 or EAXA board CN512
  • YSU or YPU unit board failure
  • EAXA board failure

First checks, in this order

  1. Open ROBOT, then OVERRUN & S-SENSOR, release and reset the alarm there
  2. Stay on that screen while you jog the robot clear
  3. If it comes back, check the YPU unit CN203 and EAXA board CN512 cables
  4. Save CMOS.BIN, then replace the YPU unit or EAXA board

Alarm 4740: M-SAF OVERRUN DETECT (DX200, YRC1000)

Hits OEE: Availability

What it means: The safety board detected that the overrun limit switch of the control group shown in the sub code tripped.[1][2][4]

Also on: YRC1000 and DX200. DX100 uses 4100 and 4101 instead.

Likely causes

  • The overrun limit switch was tripped by the arm
  • Slack or loose cable between the control group and the terminal board or safety board
  • Short circuit or ground fault on the +24V line
  • Safety board failure (ASF01 on YRC1000, YSF21 or YSF22 on DX200)
  • Blown fuse on the YSF22 board, or a failed limit switch (DX200)

First checks, in this order

  1. Open ROBOT, then OVERRUN&SHOCK SENSOR, reset the limit switch and jog the robot clear
  2. Check the cables between the control group, terminal board and safety board, and the manipulator cables
  3. Check the +24V line for a ground fault or short
  4. Replace the safety board or the limit switch if it repeats

Alarm 4107: OUT OF RANGE (ABSO DATA)

Hits OEE: Availability

What it means: When the controller powered up, an axis was not where it was at power off, by more than the allowed amount, so the controller will not trust its position. Playback and test runs stay blocked until the position is checked.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4107. Sub code shows the axis. The fuse F1 is on the SDCA01 board on YRC1000 and the EAXA21 board on DX200.

Likely causes

  • The robot or a station moved while the power was off
  • A fault in the encoder (PG) system
  • Blown fuse F1 on the servo board, when alarm 1962 board failure shows at the same time
  • Setting error, which Yaskawa checks by jogging the axis to zero and looking at the alignment marks

First checks, in this order

  1. Reset the alarm and turn servo power on
  2. Open ROBOT, then POWER ON/OFF POS, to see how far each axis moved
  3. Move to the second home position (check point) and compare its pulses with the current pulses, or jog to zero and check the alignment arrow marks
  4. If they do not match, the axis needs correcting: encoder system replacement or home position calibration
  5. If 1962 shows too, replace fuse F1 on the servo board

Alarm 4109: DC 24V POWER SUPPLY FAILURE(I/O)

Hits OEE: Availability

What it means: The 24V supply for the controller I/O is missing, usually from a blown fuse on the I/O board or a failed external 24V supply. It is not a collision alarm.[1][2][3]

Also on: YRC1000 (AIO board, also AIF21), DX200 (YIO board), DX100 (YIU unit). On YRC1000 the position of the digits in the sub code shows which AIO board (1st to 8th).

Likely causes

  • Detector circuit or connection fault (CN303 of the I/O board, I/O module cable)
  • Blown fuse on the I/O board
  • External 24V power supply fault
  • Short circuit or ground fault on I/O wiring (CN306 to CN309)
  • I/O board failure

First checks, in this order

  1. Read the sub code: ending 0001 = detector circuit, 0010 = fuse blown, 0011 = external 24V supply
  2. Check the I/O board fuse, its CN303 connector and the I/O module cable
  3. Check the external 24V supply and replace it if it is faulty
  4. Check the I/O wiring for shorts and ground faults, then replace the I/O board after saving CMOS.BIN

Alarm 4110: SHOCK SENSOR ACTION

Hits OEE: Availability

What it means: The shock sensor (the breakaway mount between the robot flange and the tool) opened, usually because the tool hit something.[1][2][3][4]

Also on: YRC1000, DX200 and DX100 all list 4110 SHOCK SENSOR ACTION.

Likely causes

  • Shock sensor tripped by a crash
  • Loose connection in the shock sensor line (ASF01 CN204 on YRC1000, YSF22 CN214/CN215 and EAXA21 CN512 on DX200, EAXA CN512 on DX100)
  • Short circuit or ground fault on the +24V line
  • Blown fuse on the YSF22 board (DX200)
  • Safety or servo board failure

First checks, in this order

  1. Open ROBOT, then OVERRUN&SHOCK SENSOR, reset the sensor and jog the robot clear
  2. Check the breakaway bracket has clicked back into place, cables are not wrapped tight around the arm and the torch is not jammed against a part
  3. Inspect the tool, tip and nozzle before restarting
  4. If it will not reset with the robot clear, check the sensor cable and connectors, then the boards

Alarm 4117: BRAKE POWER ERROR

Hits OEE: Availability

What it means: The 24V brake supply on a servo board reported a fault. The sub code tells which servo board.[1][2][3]

Also on: YRC1000 (SDCA01 board number), DX200, DX100 (EAXA or EAXB board in the sub code). Minor alarm, compare 1681 for the major brake supply alarm.

Likely causes

  • Short circuit or ground fault in the brake wiring
  • Loose brake connection
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Reset the alarm
  2. Check the brake connection for a ground fault or short
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4301: CONTACTOR ERROR

Hits OEE: Availability

What it means: The servo power contactor is not in the state the controller commanded, for example it dropped out while servo was on, or pulled in while servo was off after an emergency stop.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4301. Sub code shows the contactor number.

Likely causes

  • Contactor or power unit failure (APU01 on YRC1000)
  • Loose contactor control cables (ASF01 CN205, APU01 CN604 on YRC1000)
  • Safety board failure
  • Servo board failure

First checks, in this order

  1. Reset the alarm
  2. Switch controller power off, wait until all servo and converter LEDs are off and confirm with a tester that no charge remains
  3. Check the contactor control cables and connectors
  4. Replace the power unit, then the safety board, then the servo board, saving CMOS.BIN first

Alarm 4304: CONVERTER INPUT POWER ERROR

Hits OEE: Availability

What it means: At servo on the converter did not confirm that main power was arriving, or its ready signal was in the wrong state around an emergency stop.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4304. Sub code shows the converter number.

Likely causes

  • Power unit failure (APU01 on YRC1000)
  • Loose converter or servo board cables
  • Converter failure

First checks, in this order

  1. Reset the alarm
  2. Check the converter, servo board and power unit connectors
  3. Replace the power unit, then the converter
  4. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4307: SERVO ON DEFECTIVE SPEED

Hits OEE: Availability

What it means: An axis moved at the moment servo power came on.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4307. Sub code shows the axis.

Likely causes

  • Mechanical failure that lets the axis move at servo on
  • Brake released early because the brake relay on the servo board is broken
  • Loose motor power connections
  • Motor failure

First checks, in this order

  1. Watch whether the robot moves when servo power turns on
  2. Check that the brake is not being released by a broken brake relay
  3. Check the servo board, inverter board and power cable connections
  4. Replace the motor, then the servo board

Alarm 4311: ENCODER BACK-UP ERROR

Hits OEE: Availability

What it means: The encoder lost its stored position because its backup battery voltage dropped, so the axis needs resetting and possibly its home position registered again.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4311. Sub code shows the axis.

Likely causes

  • Encoder backup battery worn out or disconnected
  • Loose cable between encoders or at the servo board
  • Encoder failure
  • Servo board failure

First checks, in this order

  1. Replace the battery of the axis in the sub code
  2. If the home position of that axis shows ***, register the home position again
  3. If the alarm does not come back after a power cycle, the robot is fine to run
  4. If it returns, check the encoder cables, then replace the encoder or servo board

Alarm 4312: ENCODER BATTERY ERROR

Hits OEE: Availability

What it means: The encoder backup battery voltage is low (below 2.8V on YRC1000). Replace it before the axis loses its position data.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4312 ENCODER BATTERY ERROR.

Likely causes

  • Encoder backup battery worn out
  • Loose manipulator cable
  • Motor (encoder) failure

First checks, in this order

  1. Replace the encoder backup battery
  2. Reset the alarm and check the manipulator cable connections
  3. If it repeats, replace the motor

Alarm 4315: COLLISION DETECT

Hits OEE: Availability

What it means: The controller's software collision detection saw an outside force above its threshold, meaning the robot hit something or the load it thinks it carries is wrong. No external sensor is involved.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4315 COLLISION DETECT. Sub code shows the axis.

Likely causes

  • Wrong tool data (mass, center of gravity) or a collision detection level set too low
  • Robot or workpiece hitting jigs or parts
  • Too much load from automatic acceleration or deceleration after a category 1 or HOLD stop, or a cold start
  • Loose motor power or brake wiring, or an amplifier or motor failure
  • Worn speed reducer (iron powder in the grease)

First checks, in this order

  1. Look for a real crash or interference and clear it
  2. Check the tool file data and the collision detection level (Yaskawa allows up to 500% when nothing is interfering)
  3. Adjust ACC and DEC at the taught point, and warm the robot up first in a cold shop
  4. Check motor power and brake wires, then the amplifier, motor and reducer grease

Alarm 4320: OVERLOAD(CONTINUE)

Hits OEE: Availability

What it means: A motor carried 110% to 150% of its rated torque for too long, so the controller stopped it to protect the motor.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4320. Sub code shows the axis.

Likely causes

  • Tool or part heavier than the tool data says
  • Robot interfering with parts or fixtures
  • Job load factor over 100%
  • Brake not releasing because of a contactor or servo board fault
  • Damaged wiring harness in the robot or a motor failure

First checks, in this order

  1. Check the tool data mass against the real tool and part
  2. Look for interference and remove it
  3. Review the job so the load factor stays under 100%
  4. Check the brake voltage at the servo board brake connector and the motor brake terminal, then the harness and motor

Alarm 4321: OVERLOAD(MOMENT)

Hits OEE: Availability

What it means: A motor was loaded to about 200% of its rated torque, so the controller stopped it at once.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4321. Sub code shows the axis.

Likely causes

  • Tool or part heavier than the tool data says
  • Robot interfering with parts or fixtures
  • Job load factor over 100%
  • Brake held on by a contactor or servo board fault
  • Damaged wiring harness, motor, servo board or power unit failure

First checks, in this order

  1. Look for a crash or interference and remove it
  2. Check the tool data mass
  3. Review the job load factor
  4. Check the brake voltage at the servo board and motor brake terminal, then the harness and motor

Alarm 4326: OVER SPEED

Hits OEE: Availability

What it means: A motor ran faster than its allowed maximum speed.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4326. Sub code shows the axis.

Likely causes

  • Speed set too high around one point of the job
  • Touch speed or touch pressure set wrong on a servo (motor) gun
  • U, V and W motor wiring connected wrong
  • Motor failure
  • Servo board failure

First checks, in this order

  1. If it always trips at the same place, lower the speed around it
  2. For a motor gun, check the touch speed and touch pressure settings
  3. Check the U, V and W wiring
  4. Replace the motor, then the servo board

Alarm 4328: SERVO TRACKING ERROR

Hits OEE: Availability

What it means: An axis fell behind its commanded position and path by more than allowed.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4328. Sub code shows the axis.

Likely causes

  • Wrong tool or part mass in the tool data
  • Robot interfering with parts or fixtures
  • Too much load from acceleration or deceleration after a category 1 or HOLD stop, or a cold start
  • Loose motor power wiring, or a brake held on by a contactor fault
  • Power unit, amplifier or motor failure

First checks, in this order

  1. Check the tool data and look for interference
  2. Adjust ACC and DEC at the taught point and warm the robot up in a cold shop
  3. Check the inverter board, motor power and power cable connectors
  4. Check the brake voltage, then replace the power unit, amplifier or motor

Alarm 4336: OPEN PHASE(CONVERTER)

Hits OEE: Availability

What it means: One phase of the main power feeding the converter is missing.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4336. Sub code shows the converter number.

Likely causes

  • Loose converter or servo board cables
  • Supply voltage wrong or a phase missing at the breaker
  • Power unit or converter failure
  • Servo board failure

First checks, in this order

  1. Check all three incoming phases and that the breaker voltage matches the rating label on the controller door
  2. Check the converter, servo board and external axis servopack connectors
  3. Replace the power unit, then the converter
  4. Save CMOS.BIN, then replace the servo board

Alarm 4337: OVERCURRENT(AMP)

Hits OEE: Availability

What it means: More current than the amplifier allows flowed, most often from a ground fault or short in the U, V or W motor wires.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4337. Sub code shows the axis; a 4337 in the history also identifies the axis behind a 1365 GROUND FAULT.

Likely causes

  • Ground fault or short between the U, V and W motor wires
  • Loose servo board, inverter board or converter connectors
  • Damaged manipulator cable or supply cable
  • Amplifier failure
  • Motor failure

First checks, in this order

  1. Check the motor power wires of the axis shown for ground faults and shorts
  2. Check the servo board, inverter board and converter connectors
  3. Replace the manipulator cable or supply cable if damaged
  4. Replace the amplifier, then the motor, then the servo board

Alarm 4414: EXCESSIVE SEGMENT (LOW/HIGH)

Hits OEE: Availability

What it means: The motion command asked for more than the allowed maximum speed, typically near a singular point or when the wrist turns a long way around one point.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4414. Sub code shows control group and axis.

Likely causes

  • Speed too high for that step
  • Robot passing near a singular point
  • Large change of tool orientation on a single control point

First checks, in this order

  1. Lower the speed at the step where it trips
  2. Change the move to joint interpolation (MOVJ), watching for new interference because the path changes
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4416: PULSE LIMIT(MIN./MAX.)

Hits OEE: Availability

What it means: An axis was commanded past its software motion limit (pulse limit) in the minus or plus direction.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4416. Sub code shows control group and axis.

Likely causes

  • A taught step lies outside the axis motion range (setting error)
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Find the step where the alarm happened
  2. Teach that step again so it sits inside the motion range
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4418: CUBE LIMIT(MIN./MAX.)

Hits OEE: Availability

What it means: The tool center point went outside the cube (XYZ box) limit set for the robot.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4418. Sub code shows control group and XYZ.

Likely causes

  • A taught step puts the tool point outside the cube limit (setting error)
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Find the step where the alarm happened
  2. Teach that step again so the tool point stays inside the range
  3. If it repeats, save CMOS.BIN and contact Yaskawa

Alarm 4669: DETECT BRAKE SLIP

Hits OEE: Availability

What it means: The brake check found that the brake on the axis shown slips.[1][2][3]

Also on: YRC1000, DX200 and DX100 all list 4669. Sub code shows the axis.

Likely causes

  • Motor brake worn or failed
  • External brake failure
  • Check torque value set wrong

First checks, in this order

  1. Reset the alarm
  2. Check the check torque value settings
  3. If it repeats, replace the motor, or the external brake if that one is flagged

Alarm 4676: BROKEN FAN FUSE

Hits OEE: Availability

What it means: A fuse feeding the cooling fans in the power unit blew.[1][2][3]

Also on: YRC1000 (fuses 1FU and 2FU in the APU01 unit), DX200 and DX100.

Likely causes

  • Short circuit or ground fault on the fan power line
  • Fuse failure
  • Other fault that Yaskawa reviews from a CMOS.BIN backup

First checks, in this order

  1. Reset the alarm
  2. Check the fan power line for a short or ground fault
  3. Only after the short or ground fault is cleared, replace the fuse

Alarm 4741: M-SAF PPESP SIG. ERROR

Hits OEE: Availability

What it means: The two channels of the pendant emergency stop signal disagreed for longer than allowed.[1][2]

Also on: YRC1000 and DX200 (YSF22 board on DX200). Not in the DX100 alarm list.

Likely causes

  • Loose pendant cable or safety board connector (ASF01 CN203 on YRC1000)
  • Programming pendant failure
  • Safety board failure
  • Blown fuse in the painting module (explosion proof pendant version)

First checks, in this order

  1. Reset the alarm
  2. Check the pendant cable and the safety board connector, and any outside device on the pendant emergency stop line
  3. Replace the pendant cable or the pendant
  4. Replace the safety board connected to the first servo board

Alarm 4746: M-SAF SAFETY FENCE SIG. ERROR

Hits OEE: Availability

What it means: The two channels of the safety fence (gate) signal disagreed for longer than allowed.[1][2]

Also on: YRC1000 and DX200. Not in the DX100 alarm list.

Likely causes

  • Wiring fault between the fence switch and the terminal board
  • Loose cable between the safety board and terminal board (ASF01 CN206 on YRC1000)
  • Fault in an outside device on the fence signal line
  • Safety board failure

First checks, in this order

  1. Reset the alarm
  2. Check the fence switch wiring and its terminal board cable
  3. Check connectors of outside devices on the fence signal line
  4. Replace the safety board connected to the first servo board

Alarm 4973: POSITION ERROR(COLLISION DETECT)

Hits OEE: Availability

What it means: After the robot stopped for a collision detection, the position error still reached its limit.[1][2][3]

Also on: YRC1000 and DX100 list 4973 POSITION ERROR (COLLISION DETECT); DX200 lists the same number and name.

Likely causes

  • Tool information set wrong
  • Workpiece setting wrong
  • Deceleration time parameter (listed on DX100)

First checks, in this order

  1. Check the tool data
  2. Check the workpiece setting
  3. On DX100, check the deceleration time parameter
  4. If it repeats, save CMOS.BIN and contact Yaskawa

Log it, or the same alarm comes back

A robot alarm stops the cell, and often the machines it feeds, so in OEE terms it is a breakdown. Log the alarm number, the sub code and the minutes lost: the sub code usually names the axis or the board.

  • Reason code: the alarm plus the cell, for example 4107 sub code 3, weld cell 2, so an absolute data alarm that follows every battery change stands out.
  • 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.

For what to do after a robot fault, fabrico.io has a guide to industrial robot fault troubleshooting and recovery. An error code tells you what the robot controller detected, not what happened in the cell in the seconds before. Fabrico's camera-based OEE software syncs camera video with machine data, so you can replay the moment the cell stopped next to the error.

Frequently asked questions

How do I clear alarm 4107 OUT OF RANGE (ABSO DATA) on a Motoman?

Reset the alarm, turn servo power on and do a position check: move to the second home position (check point) and compare its pulses with the current pulses, or jog to zero and check the arrow marks. ROBOT, then POWER ON/OFF POS shows how far each axis moved while the power was off. If the positions match the alarm is cleared; if not, the encoder system or home position of that axis must be corrected before playback will run.

What is the difference between 4110 SHOCK SENSOR ACTION and 4315 COLLISION DETECT?

4110 comes from a physical shock sensor, the breakaway mount between the flange and the tool, opening its contact. 4315 comes from the controller's own software collision detection, which compares motor torque with the expected load. For 4110 you reset the sensor under ROBOT, then OVERRUN&SHOCK SENSOR; for 4315 you check for interference, the tool data and the collision detection level.

How do I move the robot after an overrun or shock sensor alarm?

Set the security level to editing or management, open ROBOT, then OVERRUN&S-SENSOR, press RELEASE and then RESET. Stay on that screen while you jog the robot clear, because leaving it can bring the alarm back. Then inspect the tool and the breakaway bracket and go back to the JOB to restart from where the robot stopped.

Why does RESET not clear my alarm, and what is an error?

Alarms numbered 0xxx to 3xxx are major alarms: servo power is cut and they only clear after you switch the main power off, fix the cause and switch it on again. Minor alarms (4xxx to 9xxx) clear with RESET but come straight back if the cause is still there. Errors such as 110 Turn ON servo power or 120 Set to PLAY mode are not alarms; they do not stop a running robot and are cleared with CANCEL.

What should I do about encoder battery alarms 4312 and 4311?

4312 ENCODER BATTERY ERROR is the early warning that the encoder backup battery is low, so replace it before position data is lost. 4311 ENCODER BACK-UP ERROR means the encoder already lost its position because the battery voltage dropped. Replace the battery of the axis shown and, if its home position shows ***, register the home position again.

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. YRC1000 Alarm Codes (Major Alarms) (Minor Alarms), Yaskawa manual 178644-1CD, RE-CER-A600 revision 14
  2. DX200 Maintenance Manual, Yaskawa manual 165293-1CD, RE-CHO-A113 revision 21
  3. DX100 Maintenance Manual, Yaskawa manual 155492-1CD, RE-CHO-A108 revision 28
  4. Overrun / Shock Sensor Alarm Recovery, Yaskawa Motoman Knowledge Center

See the moment the cell stopped

Fabrico, a light MES with computer vision, syncs camera footage with machine and timeline data, so you can replay the exact moment the cell stopped and review the cause next to the robot's error. 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
The lookup stays free.

Related: industrial robot troubleshooting · FANUC robot SRVO alarm codes · ABB robot error codes · Yaskawa SERVOPACK alarm codes

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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