Epson Robot Error Codes

4001: Arm reached the limit of motion range.

What it means: The destination point or the current position is outside the joint range set for the robot (the Range setting), so the motion command is refused.^[1][2][3]

Also on: 4250 is the same limit reached during a CP motion; 4011 is the XYLim area limit.

Likely causes

• Destination point taught or calculated outside the Range limits
• Current position already outside the Range limits
• Range values changed or set narrower than the points the program uses
• Point used with the wrong Tool or Local, which moves it outside the range

First checks, in this order

1. Compare the destination point and the current point with the Range settings in Epson RC+ [Tools] > [Robot Manager] > [Range].
2. Check any Range command in the program that changes the limits at run time.
3. Correct or re-teach the point so it sits inside the range, then Reset and run again.

5041: Motor torque output failure in low power state.

What it means: In low power mode (used for jogging and teaching) a motor could not deliver the torque it was told to, so the servo stopped the robot. The RC+ 8.0 list puts the brake and anything that binds the axis near the top of its checks.^[1][2][3]

Also on: 5040 is the same failure in high power state.

Likely causes

• Brake not releasing: brake release switch, external short connector or brake fault
• Mechanical binding, play, sticking or a loose belt on the axis
• Collision or contact with peripheral equipment
• Wrong robot model setting
• Power cable or internal power wiring fault (loose pin, break, short) or low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Check the model setting and the connection of the brake release switch or external short connector.
2. On robots with a brake release switch, press it for the axis that tripped and listen for the brake releasing.
3. With the controller off, the brake released and the M/C cable unplugged, move the axis by hand: it should move smoothly with no play, sticking or loose belt.
4. Check for contact with equipment, the power cable, the robot power wiring and the supply voltage.
5. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5042: Position error overflow in high power state.

What it means: While running in high power, the gap between the commanded and the actual motor position grew past the limit, so the servo stopped the robot.^[1][2][3]

Also on: 5043 is the same error in low power state.

Likely causes

• Weight or Inertia set lower than the real hand and payload
• Rough motion, backlash, loose belt or a dragging brake
• Collision or contact with peripheral equipment
• Wrong model setting, power cable or wiring fault, low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Set Weight and Inertia to match the real hand and payload, and check the load.
2. Check the arm for smooth motion, backlash, belt tension and brake drag.
3. Look for collision or contact with equipment in the cell.
4. Check the model setting, the power cable, the robot power wiring (loose pins, breaks, shorts) and the supply voltage.
5. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5043: Position error overflow in low power state.

What it means: While moving in low power (jogging or teaching), the actual motor position fell too far behind the command, so the servo stopped the robot.^[1][2][3]

Also on: 5042 is the same error in high power state.

Likely causes

• Rough motion, backlash, loose belt or a dragging brake
• Collision or contact with peripheral equipment
• Wrong model setting
• Power cable or robot power wiring fault, low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Check the arm for smooth motion, backlash, belt tension and brake drag.
2. Look for collision or contact with equipment in the cell.
3. Check the model setting, the power cable, the robot power wiring and the supply voltage.
4. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5044: Speed error overflow in high power state.

What it means: In high power, the actual motor speed differed from the commanded speed by more than the limit, so the servo stopped the robot.^[1][2][3]

Also on: 5045 is the same error in low power state.

Likely causes

• Weight or Inertia set lower than the real payload
• Rough motion, backlash, loose belt or a dragging brake
• Collision or contact with peripheral equipment
• Wrong model setting, power cable or wiring fault, low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Set Weight and Inertia to the real payload and check the load.
2. Check the arm mechanics: smooth motion, backlash, belt tension, brake.
3. Look for collision or contact with equipment.
4. Check the model setting, the power cable, the robot power wiring and the supply voltage.
5. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5040: Motor torque output failure in high power state.

What it means: In high power, a motor could not deliver the commanded torque, so the servo stopped the robot.^[1][2][3]

Also on: 5041 is the same failure in low power state.

Likely causes

• Weight or Inertia set lower than the real payload
• Rough motion, backlash, loose belt or a dragging brake
• Collision or contact with peripheral equipment
• Wrong model setting, power cable or wiring fault, low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Set Weight and Inertia to the real payload and check the load.
2. Check the arm mechanics: smooth motion, backlash, belt tension, brake.
3. Look for collision or contact with equipment.
4. Check the model setting, the power cable, the robot power wiring and the supply voltage.
5. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5057: Collision was detected in High power mode (Detection of robot motion error)

What it means: The collision detection function (robot motion error detection) stopped the robot in high power because its motion did not match what was expected.^[1][2][3]

Also on: 5058 is the low power version.

Likely causes

• The arm hit or touched something
• Torque saturation because Weight or Inertia is set too low
• Torque saturation from combined multi-joint moves or swinging a long object
• Torque saturation from a drop in supply voltage
• Hardware fault or software malfunction

First checks, in this order

1. Look for a collision or contact and rearrange the cell so the path is clear.
2. Check that Weight and Inertia match the real payload and correct them.
3. For combined multi-joint moves, reduce acceleration and deceleration.
4. Check the supply voltage.
5. If another error was logged at the same time, fix that one first. Epson RC+ User's Guide: Collision Detection Function.

2318: Cannot execute a motion command when an error has been detected.

What it means: A motion command was sent while an earlier error is still active, so the controller refuses it. The real problem is the first error in the history.^{[1][2][3][4][7]}

Also on: 2317 is the same block for starting a task.

Likely causes

• An earlier error was not reset
• The program or a remote device sends a motion command before resetting

First checks, in this order

1. Find the earlier error in the system history (Epson RC+ or the teach pendant System History panel) and fix its cause.
2. Reset the error: Reset button in the Robot Manager, the Reset command, the teach pendant [Reset] button or the remote Reset input.
3. Run the motion command again.

5016: Power supply failure of the absolute encoder. Replace the battery. Check the robot internal wiring.

What it means: The absolute encoder lost its backup power, so the stored position can no longer be trusted. The encoder must be reset and the robot calibrated before it runs again.^[1][2][3]

Also on: Also listed as 9716 in the 9000 serious error group.

Likely causes

• Robot encoder backup battery dead or removed with the controller off
• Signal cable unplugged or broken while the controller was off
• Internal wiring fault in the robot

First checks, in this order

1. Replace the robot's encoder backup battery if it is low (Manipulator manual, Maintenance).
2. Check the signal cable connection between the robot and the controller.
3. Reset the encoder with the EncReset command, then calibrate (Service/Maintenance Manual, Calibration).
4. Reboot the controller when asked (Encoder is reset. Reboot the controller.) and check known points before production.

4005: Current point position is above the specified LimZ value.

What it means: The Z axis is currently higher than the LimZ ceiling set for Jump motion, so the move cannot start.^[1][2][3]

Also on: 4006 is the same check for the target point.

Likely causes

• LimZ set lower than where the Z axis is now
• Robot jogged or moved above LimZ before the Jump
• Program sets a different LimZ than expected

First checks, in this order

1. Lower the Z axis below the LimZ value.
2. Or raise the LimZ value the program uses.
3. Reset and run again.

1108: One or more source files are updated. Please build the project.

What it means: Program files were changed after the last build, so the controller will not run the old build.^[1][2][3]

Also on: 2296 carries the same message.

Likely causes

• Program edited but not rebuilt
• Project files changed or synchronized from another PC

First checks, in this order

1. Rebuild the project in Epson RC+.
2. Run the program again.

1502: Communication disconnection between RC+ and Controller. Re-establish communication.

What it means: Epson RC+ lost its link to the controller. Note 2 in the system history gives the reason: 1 communication timeout, 2 USB cable disconnected, 3 USB reception failure, 4 USB communication shutdown.^[1][2][3]

Likely causes

• USB or Ethernet cable pulled or loose
• Controller rebooted or switched off during the session
• Network problem between the PC and the controller

First checks, in this order

1. Read Note 2 in the system history to see which reason applies.
2. Check the USB or Ethernet cable and connectors between the PC and the controller.
3. Reconnect from Epson RC+.

5054: Overload of the motor. Decrease the motion duty and the Accel.

What it means: Motor overload protection tripped: the motor has worked too hard for too long.^[1][2][3]

Also on: 5055 has the same text with operation duty.

Likely causes

• Duty too high (too little dwell between moves)
• Accel set too high
• Weight or Inertia set wrong
• Backlash, heavy load, loose belt or a dragging brake

First checks, in this order

1. Lower the motion duty (add wait time) and reduce Accel.
2. Check that Weight and Inertia match the real payload.
3. Check the robot for backlash, heavy load, belt tension and brake drag.

9001: Emergency stop circuit failure was detected. Disconnection or other failure was found in one of the redundant inputs.

What it means: The two redundant channels of the emergency stop circuit disagree. This is a wiring or hardware fault in the E-stop circuit, not just a pressed button.^[1][2][3][4]

Also on: 4150 reports the same channel mismatch when it lasts more than two seconds.

Likely causes

• Broken wire on one channel of the emergency stop input
• Earth fault or short in the emergency stop wiring
• One contact of an emergency stop switch failing

First checks, in this order

1. Check the emergency stop input wiring for breaks, earth faults and shorts on both channels.
2. Check each emergency stop switch connected to the circuit.
3. Reboot the controller: a 9000s error is not cleared by the Reset input.

0413: The grease alarm for the ball screw spline occurred.

What it means: The controller's maintenance alarm says the grease interval of the ball screw spline (SCARA Z axis) has run out. The robot keeps running, but grease it soon.^[1][2][3][4]

Also on: Printed as 413 in the code list; 423 has the same text.

Likely causes

• Grease interval reached
• Alarm not reset after the last greasing

First checks, in this order

1. Grease the ball screw spline as described in the Manipulator manual (Greasing).
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance]. Epson says only Epson RC+, TP3 or TP4 can reset it.
3. Note 1 and Note 2 show the consumption rate and the limit (times 1000).

5072: Servo alarm B.

What it means: A servo alarm that Epson's list does not describe further. The listed remedy is to clear it with Reset or by rebooting the controller.^[1][2][3]

Likely causes

• Cause not described in the Epson code list; look for other servo errors logged at the same time

First checks, in this order

1. Clear it with Reset (Robot Manager, Reset command or teach pendant) or reboot the controller.
2. Check the system history for 5000s servo errors logged at the same moment and treat those.
3. If it keeps coming back, contact the Epson supplier for your region.

2309: Cannot execute a motion command while the safeguard is open.

What it means: The safeguard (safety door) input is open, so motion commands are blocked.^[1][2][3][4]

Likely causes

• Cell door, light curtain or other safeguard open
• Interlock switch or safeguard wiring fault
• Program tries to move before the safeguard is closed

First checks, in this order

1. Close the safeguard and confirm Safety is no longer shown on the Epson RC+ status bar.
2. Reset, then run the motion again.
3. If the door is closed but the state stays open, check the interlock switch and the safeguard input on the EMERGENCY connector.

4025: Cannot execute a motion command during emergency stop condition.

What it means: An emergency stop is active, so the robot will not accept a motion command.^[1][2][3][7]

Likely causes

• Emergency stop switch pressed (controller, teach pendant or external)
• Emergency stop not reset after release

First checks, in this order

1. Release the emergency stop switch.
2. Reset (Robot Manager Reset button, Reset command or teach pendant [Reset]).
3. Run the motion again.

1041: Cannot execute during Emergency Stop status.

What it means: A command was refused because the controller is in emergency stop.^[1][2][3]

Likely causes

• Emergency stop switch pressed
• Emergency stop released but not reset

First checks, in this order

1. Release the emergency stop switch.
2. Reset to clear the emergency stop status, then repeat the command.

1042: Cannot execute while the safeguard is open.

What it means: A command was refused because the safeguard input is open.^[1][2][3]

Likely causes

• Safety door or other safeguard open
• Safeguard interlock wiring fault

First checks, in this order

1. Close the safeguard.
2. Check the interlock switch if the state does not change.

1043: Cannot execute during error condition.

What it means: A command was refused because an earlier error is still active.^[1][2][3]

Likely causes

• Earlier error not reset

First checks, in this order

1. Find and fix the earlier error in the system history.
2. Reset the error condition, then repeat the command.

2317: Cannot execute the task when an error has been detected.

What it means: A task could not start because an error is still active.^[1][2][3]

Also on: 2318 is the same block for motion commands.

Likely causes

• Earlier error not reset before starting the program

First checks, in this order

1. Fix the earlier error, reset it with Reset, then start the task.

4006: Target point position is above the specified LimZ value.

What it means: The target point's Z is higher than the LimZ ceiling set for Jump motion.^[1][2][3]

Likely causes

• Target point taught higher than LimZ
• LimZ set too low for the points used

First checks, in this order

1. Lower the Z coordinate of the target point.
2. Or raise the LimZ value the program uses.

4007: Coordinates conversion error. The end/mid point is out of the motion area. Jogging to the outside of the motion area.

What it means: The end or middle point of the move, or a jog step, lies outside the area the robot can reach, so it cannot be converted to joint positions.^[1][2][3]

Likely causes

• Point coordinates outside the robot's reach
• Wrong Tool, Local or arm orientation for the point
• Jogging past the edge of the motion area

First checks, in this order

1. Check that the point coordinates are inside the motion range.
2. Check the Tool and Local the point uses.
3. Jog back inside the motion area.

4011: Arm reached the limit of XY motion range specified by XYLim statement.

What it means: The move would leave the XY area set with XYLim.^[1][2][3]

Likely causes

• Point outside the XYLim area
• XYLim area set too small

First checks, in this order

1. Check the area set by the XYLim statement.
2. Correct the point or the XYLim values.

4250: Arm reached the limit of motion range during the operation.

What it means: The arm hit the Range limit partway through a move, usually on a CP (straight line or arc) path that passes outside the range.^[1][2][3]

Likely causes

• CP motion path leaves the motion range even though both end points are inside

First checks, in this order

1. Check that the whole CP path stays inside the motion range.
2. Add a via point or change the path.

4024: Cannot complete the arm positioning using the current Fine specification.

What it means: The arm did not settle inside the Fine positioning window in time.^[1][2][3]

Likely causes

• Vibration of the robot or tooling
• Loose parts or screws
• Fine value set too tight

First checks, in this order

1. Check that the robot does not vibrate and that all parts and screws are tight.
2. Increase the Fine setting value.

4031: Cannot execute a motion command when the motor is in the off state.

What it means: A motion command was sent while motor power is off.^[1][2][3]

Likely causes

• Motor not turned on after start up, an error or an emergency stop

First checks, in this order

1. Turn motor power on (Motor On), then run the motion command.

4242: Improper acceleration reference was generated.

What it means: The robot was asked to accelerate harder than the allowed value.^[1][2][3]

Likely causes

• AccelS too high for a CP motion
• Conveyor tracking acceleration (Cnv_Accel) too high

First checks, in this order

1. For CP motion, reduce AccelS.
2. With a conveyor, also reduce Cnv_Accel.

4099: Servo error was detected during operation.

What it means: A servo error stopped the motion. The detailed cause is a 5000s error logged at the same time.^[1][2][3]

Likely causes

• A 5000s servo error (torque, position, speed, overload, encoder)

First checks, in this order

1. Look in the system history for a 5000s error at the same moment and follow its remedy.

5045: Speed error overflow in low power state.

What it means: In low power, the actual motor speed differed from the commanded speed by more than the limit.^[1][2][3]

Likely causes

• Rough motion, backlash, loose belt or a dragging brake
• Collision or contact with peripheral equipment
• Wrong model setting, power cable or wiring fault, low supply voltage
• Failed motor driver, DMB or motor

First checks, in this order

1. Check the arm mechanics: smooth motion, backlash, belt tension, brake.
2. Look for collision or contact with equipment.
3. Check the model setting, the power cable, the robot power wiring and the supply voltage.
4. If it repeats, replace in order the motor driver, the DMB, then the motor (T/VT series: also the CPU board and motor unit).

5046: Over speed in high power state.

What it means: A motor ran faster than allowed in high power, often during a CP motion near a pose where one joint has to spin fast.^[1][2][3]

Likely causes

• SpeedS too high for the CP motion
• CP path orientation that forces a joint to turn very fast
• Weight or Inertia set wrong
• Mechanical, wiring or supply voltage problem

First checks, in this order

1. Reduce SpeedS of the CP motion or change its orientation.
2. Set Weight and Inertia to the real payload.
3. Check the arm mechanics, the power cable and wiring, and the supply voltage.
4. If it repeats, replace in order the motor driver, the DMB, then the motor.

5058: Collision was detected in Low power mode (Detection of robot motion error)

What it means: Collision detection stopped the robot in low power because its motion did not match what was expected.^[1][2][3]

Also on: 5057 is the high power version.

Likely causes

• The arm hit or touched something
• Hand or object heavier than the robot specification
• Hardware fault or software malfunction

First checks, in this order

1. Look for a collision or contact and clear the path.
2. Check the hand weight and correct the setting.
3. 6-axis robots, joints 4 and 5: if torque saturates, hold the load in high power mode.
4. If another error was logged at the same time, fix that one first.

5055: Overload of the motor. Decrease the operation duty and the Accel.

What it means: Motor overload protection tripped after too much work over time.^[1][2][3]

Also on: Same remedy as 5054.

Likely causes

• Duty too high or Accel too high
• Weight or Inertia set wrong
• Backlash, heavy load, loose belt or a dragging brake

First checks, in this order

1. Lower the motion duty and reduce Accel.
2. Check Weight and Inertia.
3. Check the robot for backlash, heavy load, belt tension and brake drag.

5049: Over current of the motor driver.

What it means: The motor driver saw current above its limit, usually from a short or earth fault on the motor power line.^[1][2][3]

Likely causes

• Short circuit or earth fault in the power cable or robot power wiring
• Failed motor driver or DMB

First checks, in this order

1. With power off, check the power line for shorts and earth faults.
2. Then replace the motor driver, then the DMB.
3. T/VT series: check the power cable for shorts and earth faults, then reboot or replace the motor unit.

5048: Over voltage of the main power circuit.

What it means: The main power circuit voltage went too high, typically from energy fed back while braking a heavy load.^[1][2][3]

Likely causes

• Heavy load or Weight and Inertia set wrong
• Regeneration module problem
• Supply voltage problem
• Wiring fault or failed driver, DMB or motor

First checks, in this order

1. Check the main power voltage and the regeneration module.
2. Set Weight and Inertia to the real payload and check the load.
3. Check the arm mechanics, the power cable and the robot power wiring.
4. If it repeats, replace in order the motor driver, the DMB, then the motor.

5017: Backup data failure of the absolute encoder. Reset the encoder.

What it means: The position data kept in the absolute encoder is not valid, so the encoder must be reset and the robot calibrated.^[1][2][3]

Also on: Also listed as 9717 in the 9000 group.

Likely causes

• Encoder backup lost (battery or cable) while the controller was off
• Signal cable fault

First checks, in this order

1. Check the signal cable connection.
2. Reset the encoder with EncReset, then calibrate (Service/Maintenance Manual, Calibration).

5018: Absolute encoder battery alarm.

What it means: The absolute encoder reports a low backup battery.^[1][2][3]

Likely causes

• Robot encoder backup battery worn out
• Signal cable fault

First checks, in this order

1. Replace the battery.
2. Check the signal cable connection.

5019: Position failure of the absolute encoder. Reset the encoder. Replace the motor.

What it means: The absolute encoder's position value is wrong.^[1][2][3]

Likely causes

• Encoder data lost or corrupted
• Encoder (motor) failure

First checks, in this order

1. Reset the encoder with EncReset and calibrate.
2. If it returns, replace the motor (encoder failure). T/VT series: reboot and replace the motor unit.

5001: Disconnection of the parallel encoder signal. Check the signal cable connection or the robot internal wiring.

What it means: The controller lost the encoder signal from a motor.^[1][2][3]

Likely causes

• M/C cable signal fault
• Robot signal wiring: loose pin, break or short
• Connector loose in the controller or plugged into the wrong encoder terminal on the DMB
• Wrong model setting, encoder (motor) or DMB failure
• Faulty wiring on the Emergency or I/O connectors

First checks, in this order

1. Check the M/C cable signal and the robot signal wiring.
2. Check the connectors inside the controller.
3. Check the model setting and the Emergency and I/O wiring.
4. Then replace the motor, then the DMB (T/VT series: reboot, reduce noise, replace the motor unit).

5098: High temperature of the encoder.

What it means: A motor encoder is too hot, usually from a high duty cycle or a mechanical load problem.^[1][2][3]

Likely causes

• Duty too high
• Weight or Inertia set wrong
• Backlash, heavy load, loose belt, brake drag or a reduction gear problem

First checks, in this order

1. Wait for the encoder to cool down.
2. Lower the motion duty.
3. Check Weight and Inertia.
4. Check the robot and its reduction gear unit.

5099: The motor driver temperature is high.

What it means: A motor driver in the controller is overheating.^[1][2][3]

Likely causes

• Clogged controller fan filter
• High ambient temperature
• Duty too high or Weight and Inertia set wrong

First checks, in this order

1. Clean the controller cooling fan filter.
2. Lower the ambient temperature.
3. Lower the motion duty and check Weight and Inertia.

0737: Low voltage from the encoder battery. Replace the battery.

What it means: The battery that backs up the robot's encoders is getting low. Replace it before the encoders lose their position.^[1][2][3][4]

Likely causes

• Encoder backup battery near the end of its life
• Battery cable connection fault

First checks, in this order

1. Replace the battery using the procedure in the Manipulator manual (Maintenance). Epson's list says to turn the controller off first; follow the manual's steps for your robot.
2. Check the cable connection.
3. If the warning stays, Epson lists replacing the CPU board.

0410: The battery alarm for the controller occurred.

What it means: The maintenance alarm says the controller battery has reached its replacement point.^[1][2][3][4]

Also on: Printed as 410 in the code list; 420 has the same text.

Likely causes

• Controller battery life used up per the alarm setting

First checks, in this order

1. Replace the battery.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0411: The battery alarm for the robot occurred.

What it means: The maintenance alarm says the robot battery (encoder backup) has reached its replacement point.^[1][2][3][4]

Also on: Printed as 411 in the code list; 421 has the same text.

Likely causes

• Robot battery life used up per the alarm setting

First checks, in this order

1. Replace the battery.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0412: The belt alarm occurred.

What it means: The maintenance alarm says a timing belt has reached its replacement point.^[1][2][3][4]

Also on: Printed as 412 in the code list; 422 has the same text.

Likely causes

• Timing belt life used up per the alarm setting

First checks, in this order

1. Replace the timing belt.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0414: The motor alarm occurred.

What it means: The maintenance alarm says a motor has reached its replacement point.^[1][2][3][4]

Also on: Printed as 414 in the code list; 424 has the same text.

Likely causes

• Motor life used up per the alarm setting

First checks, in this order

1. Replace the motor.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0415: The gear alarm occurred.

What it means: The maintenance alarm says a gear unit has reached its replacement point.^[1][2][3][4]

Also on: Printed as 415 in the code list; 425 has the same text.

Likely causes

• Gear unit life used up per the alarm setting

First checks, in this order

1. Replace the gear units.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0416: The ball screw spline alarm occurred.

What it means: The maintenance alarm says the ball screw spline has reached its replacement point.^[1][2][3][4]

Also on: Printed as 416 in the code list; 426 has the same text.

Likely causes

• Ball screw spline life used up per the alarm setting

First checks, in this order

1. Replace the ball screw spline.
2. Reset the alarm in Epson RC+ [Tools] > [Controller] > [Maintenance].

0511: Battery voltage of the CPU board backup is lower than the allowed voltage. Replace the CPU board battery.

What it means: The CPU board backup battery is low. If it dies with power off, backed up data such as Global Preserve variables can be lost.^[1][2][3][4]

Also on: 9011 is the serious error version of the same check.

Likely causes

• CPU board battery near the end of its life

First checks, in this order

1. Replace the CPU board battery right away.
2. Keep the controller powered on as much as possible until the battery is replaced.

0514: Internal temperature of the Controller is higher than the specified temperature.

What it means: The controller is running hot inside.^[1][2][3][4]

Also on: 9014 is the serious error version.

Likely causes

• High ambient temperature around the controller
• Clogged filter

First checks, in this order

1. Stop the controller as soon as you can and check the ambient temperature.
2. Check that the filter is not clogged.

0515: Rotating speed of the controller fan is below the allowed speed. (FAN1)

What it means: Controller fan 1 is turning too slowly.^[1][2][3][4]

Also on: 0516 is the same check for FAN2.

Likely causes

• Clogged filter
• Worn fan

First checks, in this order

1. Check that the filter is not clogged.
2. If the warning stays after a controller reboot, replace the fan.

0513: 24 V input voltage for the motor brake, encoder and fan is lower than the specified voltage.

What it means: The 24 V supply for brakes, encoders and fans is low.^[1][2][3][4]

Likely causes

• Failing 24 V power supply

First checks, in this order

1. Measure the 24 V supply on its own; if it does not give normal voltage, replace the power supply.

0502: Memory has been initialized.

What it means: Backed up memory was cleared, so the Global Preserve variables were reset.^[1][2][3][4]

Likely causes

• CPU board battery empty
• CPU board fault or a CPU board just replaced

First checks, in this order

1. Replace the CPU board battery.
2. If it continues, replace the CPU board.
3. After a CPU board change, reboot the controller if this shows at the first start.

0598: Robot stopped due to collision detection

What it means: Collision detection stopped the robot, logged in the warning range.^[1][2][3][4]

Likely causes

• Arm touched or hit something

First checks, in this order

1. Move the manipulator away in the direction that clears the collision.
2. Check for 5057 or 5058 in the system history.

0736: Encoder is reset. Reboot the controller.

What it means: An encoder reset was done and the controller needs a reboot to use it.^[1][2][3][4]

Also on: 5015 has the same message in the error range.

Likely causes

• EncReset executed after an encoder error or a motor change

First checks, in this order

1. Reboot the controller, then calibrate if not done yet.

0752: Servo alarm D.

What it means: A servo warning that Epson's list does not describe further and gives no remedy for.^[1][2][3][4]

Likely causes

• Cause not described in the Epson code list

First checks, in this order

1. Check the system history for servo errors logged around the same time.
2. If it repeats, contact the Epson supplier for your region.

2300: Robot in use. Cannot execute the motion command when other task is using the robot.

What it means: Two tasks tried to move the same robot. Note 1 gives the task number that already holds the robot.^[1][2][3]

Likely causes

• Motion commands for one robot sent from more than one task

First checks, in this order

1. Review the program so only one task moves the robot at a time (Note 1 shows the other task).

2301: Cannot execute the motion command until re-gripping the Enable Switch.

What it means: In teach mode the enable switch has to be released and gripped again before the next move.^[1][2][3]

Likely causes

• Enable switch held through an earlier stop or error

First checks, in this order

1. Release the enable switch, grip it again, then run the motion command.

2308: Cannot turn on the motor because of a critical error.

What it means: A critical error happened earlier, so motor power stays off until it is fixed and the controller rebooted.^[1][2][3][4]

Likely causes

• An earlier critical (9000s) error

First checks, in this order

1. Find the earlier error in the error history and fix its cause.
2. Reboot the controller.

2312: Cannot execute a task during emergency stop condition.

What it means: A task cannot start while the emergency stop is active.^[1][2][3]

Likely causes

• Emergency stop pressed or not reset

First checks, in this order

1. Check the emergency stop status, release the switch and Reset.

2313: Cannot continue execution immediately after opening the safeguard.

What it means: The program was continued too soon after the safeguard opened. Epson requires more than 1.5 seconds between opening and closing the safeguard and turning the motors on.^[1][2][3]

Likely causes

• Door opened and closed, then Continue pressed within 1.5 seconds

First checks, in this order

1. Wait at least 1.5 seconds after the safeguard opened, close it, then continue.

2222: Local number is not defined.

What it means: The program uses a Local coordinate system that has not been set. Note 1 gives the Local number.^[1][2][3]

Likely causes

• Local not defined on this controller
• Wrong Local number in the program or point

First checks, in this order

1. Check the Local setting for the number in Note 1.
2. Review the program.

2228: Pulse for the home position is not defined.

What it means: A Home command was used but the home position pulses have not been set.^[1][2][3]

Likely causes

• HomeSet not configured

First checks, in this order

1. Check the HomeSet setting and define the home position.

2230: Tool number is not defined.

What it means: The program uses a Tool that has not been set. Note 1 gives the Tool number.^[1][2][3]

Likely causes

• Tool not defined on this controller
• Wrong Tool number in the program

First checks, in this order

1. Check the Tool setting for the number in Note 1.
2. Review the program.

2240: Array subscript is out of user defined range. Cannot access or update beyond array bounds.

What it means: The program read or wrote an array element outside the declared size.^[1][2][3]

Likely causes

• Index variable larger than the array size
• Loop counter running one step too far

First checks, in this order

1. Check the array subscript (Note 1 and Note 2 show the dimension and the subscript used).
2. Review the program.

2242: Zero '0' was used as a divisor.

What it means: The program divided by zero.^[1][2][3]

Likely causes

• Variable used as a divisor is zero, for example an unset count or a sensor value

First checks, in this order

1. Review the program and guard the division against zero.

2264: Command argument is out of the available range. Check the arguments.

What it means: A command got an argument outside its allowed range. Note 1 is the value passed, Note 2 is which argument.^[1][2][3]

Likely causes

• Wrong value or variable passed to a SPEL+ command

First checks, in this order

1. Use Note 1 and Note 2 to find the argument, then check its allowed range in the online help.
2. Review the program.

2280: Timeout period set by the TMOut statement expired before the wait condition was completed in the WAIT statement.

What it means: A Wait statement waited longer than the TMOut time for its condition, often a sensor or I/O signal that never came.^[1][2][3]

Likely causes

• Input signal not arriving (sensor, wiring, upstream machine)
• TMOut time too short

First checks, in this order

1. Find out why the wait condition did not complete, for example check the input signal.
2. Check that the TMOut time suits the process.

2344: I/O input/output bit number is out of available range or the board is not installed.

What it means: The program used an I/O bit that does not exist on this controller. Note 1 gives the bit number.^[1][2][3]

Likely causes

• Wrong bit number in the program
• Expansion I/O or fieldbus I/O board missing or not detected

First checks, in this order

1. Review the program bit number.
2. Check that the expansion I/O and fieldbus I/O boards are correctly detected.

2510: Specified I/O label is not defined.

What it means: The program used an I/O label name that is not registered.^[1][2][3]

Likely causes

• Label missing or misspelled in the I/O label file

First checks, in this order

1. Check the I/O label file and add or correct the label.

2513: Specified point label is not defined.

What it means: The program used a point label that is not registered in the loaded point file.^[1][2][3]

Likely causes

• Label missing from the point file
• Different point file loaded

First checks, in this order

1. Check the point file and the label name.

1025: Execution in Teach mode is prohibited.

What it means: The command cannot run while the controller is in Teach mode.^[1][2][3]

Likely causes

• Mode selector left in Teach

First checks, in this order

1. Change to AUTO mode, then repeat the command.

1503: Disconnection while executing a task.

What it means: The console device lost its connection while a task was running.^[1][2][3]

Likely causes

• Cable or network loss between the console device and the controller

First checks, in this order

1. Check the connection between the console device and the controller.

1506: Communication disconnection between TP and Controller. Re-establish communication.

What it means: The teach pendant lost its link to the controller.^[1][2][3]

Likely causes

• Teach pendant cable or connector fault

First checks, in this order

1. Check the connection between the teach pendant and the controller, then reconnect.

2952: TEACH/AUTO switching key input signal failure was detected.

What it means: The controller read an invalid signal from the teach pendant mode selector key switch.^[1][2][3]

Likely causes

• Key switch left between positions
• Teach pendant not connected properly

First checks, in this order

1. Set the key switch firmly to TEACH or AUTO.
2. Check that the teach pendant is connected properly.

2953: ENABLE key input signal failure was detected.

What it means: The controller read an invalid signal from the enable switch.^[1][2][3]

Likely causes

• Teach pendant not connected properly
• Enable switch fault

First checks, in this order

1. Check that the teach pendant is connected properly.

2954: Relay weld was detected.

What it means: A relay contact has welded shut, probably from overcurrent caused by a short circuit.^[1][2][3]

Likely causes

• Short circuit causing overcurrent

First checks, in this order

1. Find and fix the cause of the overcurrent first.
2. Then replace the DPB.

4150: Redundant input signal failure of the emergency stop.

What it means: The two redundant emergency stop inputs have disagreed for more than two seconds.^[1][2][3]

Also on: 9001 is the serious error for the same circuit.

Likely causes

• Break, earth fault or short on one channel of the emergency stop input

First checks, in this order

1. Check the emergency stop input wiring for breaks, earth faults and shorts.
2. Reboot the controller.

4151: Redundant input signal failure of the safeguard.

What it means: The two redundant safeguard inputs have disagreed for more than two seconds.^[1][2][3]

Also on: 9002 is the serious error for the same circuit.

Likely causes

• Break, earth fault or short on one channel of the safeguard input
• Door switch with one contact failing

First checks, in this order

1. Check the safeguard input wiring for breaks, earth faults and shorts.
2. Reboot the controller.

4152: Relay welding error of the main circuit.

What it means: A main circuit relay welded, caused by overcurrent in the power system.^[1][2][3]

Likely causes

• Power system overcurrent

First checks, in this order

1. Replace the controller; Epson also lists replacing the robot.

4154: Temperature of regeneration resistor was higher than the specified temperature.

What it means: The braking (regeneration) resistor overheated because the robot's duty is too high.^[1][2][3]

Likely causes

• Duty too high
• Accel too high

First checks, in this order

1. Lengthen the wait time or reduce Accel.
2. If it trips even at lower duty, replace the DPB.

4224: Low voltage of the main circuit power supply is detected. Check the power supply voltage. Reboot the controller.

What it means: The main circuit supply voltage dropped too low.^[1][2][3]

Also on: 9624 is the serious error version.

Likely causes

• Supply voltage dip or weak supply

First checks, in this order

1. Check the power supply voltage.
2. Reboot the controller.

9002: Safeguard circuit failure was detected. Disconnection or other failure was found in one of the redundant inputs.

What it means: The two redundant channels of the safeguard circuit disagree: a wiring or hardware fault in the safety door circuit.^[1][2][3][4]

Also on: 4151 reports the same mismatch.

Likely causes

• Broken wire on one safeguard channel
• Earth fault or short in the safeguard wiring
• Door switch with one contact failing

First checks, in this order

1. Check the safeguard input wiring for breaks, earth faults and shorts.
2. Reboot the controller: a 9000s error is not cleared by the Reset input.

9011: Battery voltage of the CPU board backup is lower than the specified voltage. Replace the CPU board battery.

What it means: Serious error version of the CPU board battery check: the backup battery is too low.^[1][2][3]

Also on: 0511 is the warning version.

Likely causes

• CPU board battery used up

First checks, in this order

1. Replace the CPU board battery right away.
2. Keep the controller on as long as possible until the battery is replaced.

9014: Internal temperature of the Controller is higher than the specified temperature.

What it means: Serious error version of the controller temperature check.^[1][2][3]

Also on: 0514 is the warning version.

Likely causes

• High ambient temperature
• Clogged filter

First checks, in this order

1. Stop the controller as soon as possible and check the ambient temperature.
2. Check that the filter is not clogged.

9716: Power supply failure of the absolute encoder. Replace the battery to a new one. Check the robot internal wiring.

What it means: Serious error version of 5016: the absolute encoder lost its backup power.^[1][2][3]

Also on: 5016 has the same message in the 5000 group.

Likely causes

• Robot encoder battery dead
• Signal cable or internal wiring fault

First checks, in this order

1. Replace the battery and check the signal cable connection.
2. Reset the encoder (EncReset) and calibrate (Service/Maintenance Manual, Calibration).