Mitsubishi FR-E700 Fault Codes List

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Access the complete reference guide for Mitsubishi FR-E700 compact drive fault codes. Learn to diagnose E.OC1 and E.THM errors, use the built-in USB port, and reset faults.

Mitsubishi FR-E700 Fault Codes Reference Table

Use the search bar below or browse the table to identify your specific error code.

Mitsubishi FR-E700 Inverter Faults and Alarms

Causes and Corrective Actions

Fault Code and Meaning Cause and Remedy
HOLD

Operation panel lock		 Cause: Operation lock mode is set. Operation other than STOP/RESET is invalid.

Remedy: Press (MODE) for 2s to release lock.
LOCD

Password locked		 Cause: Password function is active. Display and setting of parameter is restricted.

Remedy: Enter the password in Pr. 297 Password lock/unlock to unlock the password function before operating.
Er1

Write disable error		 Cause:
  • You attempted to make parameter setting when Pr. 77 Parameter write selection has been set to disable parameter write.
  • Frequency jump setting range overlapped.
  • Check the setting of Pr. 77.
  • Check the settings of Pr. 31 to Pr. 36 (frequency jump).


Remedy: (Check settings listed in Cause).
Er2

Write error during operation		 Cause:
  • Parameter write was performed during operation with a value other than "2" in Pr. 77 and the STF (STR) is ON.
  • Check the Pr. 77 setting.
  • Check that the inverter is not operating.


Remedy:
  • Set "2" in Pr. 77.
  • After stopping operation, make parameter setting.
Er4

Mode designation error		 Cause:
  • Appears if a parameter setting is attempted in the NET operation mode with Pr. 77 ≠ "2".
  • Check that operation mode is PU operation mode.
  • Check the Pr. 77 setting.


Remedy:
  • After setting the operation mode to the "PU operation mode", make parameter setting.
  • After setting Pr. 77 = "2", make parameter setting.
Err.

Inverter reset		 Cause:
  • Appears at the execution of a reset command, which is given via CC-Link communication or from STOP/RESET on the operation panel.
  • Appears at powering OFF.


Remedy: Turn OFF the reset command.
OL

Stall prevention (overcurrent)		 Cause: The inverter current exceeded the stall prevention operation level (Pr. 22). This function stops frequency increase (during accel), reduces frequency (during constant speed), or stops frequency decrease (during decel) to prevent overcurrent trip.
  • Check that the Pr. 0 Torque boost setting is not too large.
  • Check that the Pr. 7 Acceleration time and Pr. 8 Deceleration time settings are not too small.
  • Check that the load is not too heavy.
  • Are there any failure in peripheral devices?
  • Check that the Pr. 13 Starting frequency is not too large.
  • Check that the Pr. 22 Stall prevention operation level is appropriate.


Remedy:
  • Increase or decrease the Pr. 0 Torque boost setting 1% by 1% and check the motor status.
  • Set a larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time.
  • Reduce the load weight.
  • Try Advanced magnetic flux vector control and General-purpose magnetic flux vector control.
  • Change the Pr. 14 Load pattern selection setting.
  • Set stall prevention operation current in Pr. 22. (Initial value 150%).
  • Increase the stall prevention operation level with Pr. 22, or disable stall prevention with Pr. 156.
oL

Stall prevention (overvoltage)		 Cause:
  • If regenerative energy of the motor becomes excessive (exceeds capability), the function stops frequency decrease to prevent overvoltage trip.
  • Check for sudden speed reduction.
  • Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used.


Remedy: The deceleration time may change. Increase the deceleration time using Pr. 8 Deceleration time.
PS

PU stop		 Cause:
  • Stop with STOP/RESET on the operation panel is set in Pr. 75 Reset selection/PU stop selection.
  • Check for a stop made by pressing STOP/RESET on the operation panel.


Remedy: Turn the start signal OFF and release with PU/EXT.
RB

Regenerative brake prealarm		 Cause:
  • Appears if the regenerative brake duty reaches or exceeds 85% of the Pr. 70 value.
  • Check that the brake resistor duty is not high.
  • Check that Pr. 30 and Pr. 70 settings are correct.


Remedy:
  • Increase the deceleration time.
  • Check that the Pr. 30 Regenerative function selection and Pr. 70 Special regenerative brake duty settings.
TH

Electronic thermal relay function prealarm		 Cause:
  • Appears if the cumulative value of the Pr. 9 Electronic thermal O/L relay reaches or exceeds 85% of the preset level.
  • Check for large load or sudden acceleration.
  • Is the Pr. 9 Electronic thermal O/L relay setting appropriate?


Remedy:
  • Reduce the load and frequency of operation.
  • Set an appropriate value in Pr. 9 Electronic thermal O/L relay.
MT

Maintenance signal output		 Cause:
  • Indicates that the cumulative energization time of the inverter has reached a given time.
  • The Pr. 503 Maintenance timer setting is larger than the Pr. 504 Maintenance timer alarm output set time setting.


Remedy: Setting "0" in Pr. 503 Maintenance timer erases the signal.
UV

Undervoltage		 Cause:
  • Power supply voltage decreased (below approx 115VAC or 230VAC for 400V class), control circuit will not perform normal functions.
  • Check that the power supply voltage is normal.


Remedy: Check the power supply system equipment such as power supply.
SA

Safety stop		 Cause:
  • Appears when safety stop function is activated (during output shutoff).
  • If the indication appears when safety stop function is not used, check that shorting wires between S1 and PC, S2 and PC are connected.


Remedy:
  • When not using the safety stop function, short across terminals S1 and PC and across S2 and PC with shorting wire.
  • If SA is indicated when terminals are shorted, internal failure might be the cause. Check wiring of terminals S1, S2 and PC.
EV

24V external power supply operation 		Cause:
  • Check if the 24V external power is supplied.
  • Check if the power supply for the inverter (main circuit) is ON. Check if the power supply voltage is low.
  • Check if the jumper between terminal P/+ and P1 is removed.

Remedy:
  • Turn ON the power supply for the inverter (main circuit).
  • If "EV" appears by turning ON the power supply of the inverter (main circuit) while the external 24V power is supplied, check the power supply (for the main circuit).
  • Check if the jumper is installed securely between terminal P/+ and P1.
FN

Fan alarm 		Cause:
  • Check the cooling fan for an alarm.

Remedy:
  • Check for fan alarm. Please contact your sales representative.
E.OC1

Overcurrent trip during acceleration 		Cause:
  • Check for sudden acceleration.
  • Check that the downward acceleration time is not long for lifts.
  • Check for output short-circuit/ground fault.
  • Check that the Pr. 3 Base frequency setting is not 60Hz when the motor rated frequency is 50Hz.
  • Check if the stall prevention operation level is set too high.
  • Check if the fast-response current limit operation is disabled.
  • Check that regeneration is not performed frequently.

Remedy:
  • Increase the acceleration time. (Shorten the downward acceleration time for lifts.)
  • When "E.OC1" is always lit at starting, disconnect the motor once and start the inverter. If "E.OC1" is still lit, contact your sales representative.
  • Check the wiring to make sure that output short circuit/ground fault does not occur.
  • Set 50Hz in Pr. 3 Base frequency.
  • Lower the setting of stall prevention operation level.
  • Activate the fast-response current limit operation.
  • Set base voltage (rated voltage of the motor, etc.) in Pr. 19 Base frequency voltage.
E.OC2

Overcurrent trip during constant speed 		Cause:
  • Check for sudden load change.
  • Check for output short-circuit/ground fault.
  • Check if the stall prevention operation level is set too high.
  • Check if the fast-response current limit operation is disabled.

Remedy:
  • Keep load stable.
  • Check the wiring to make sure that output short circuit/ground fault does not occur.
  • Lower the setting of stall prevention operation level.
  • Activate the fast-response current limit operation.
E.OC3

Overcurrent trip during deceleration or stop 		Cause:
  • Check for sudden speed reduction.
  • Check for output short-circuit/ground fault.
  • Check for too fast operation of the motor's mechanical brake.
  • Check if the stall prevention operation level is set too high.
  • Check if the fast-response current limit operation is disabled.

Remedy:
  • Increase the deceleration time.
  • Check the wiring to make sure that output short circuit/ground fault does not occur.
  • Check the mechanical brake operation.
  • Lower the setting of stall prevention operation level.
  • Activate the fast-response current limit operation.
E.OV1

Regenerative overvoltage trip during acceleration 		Cause:
  • Check for too slow acceleration (e.g. during downward acceleration in vertical lift load).
  • Check that the setting of Pr. 22 Stall prevention operation level is not too small.

Remedy:
  • Decrease the acceleration time.
  • Check that regeneration avoidance function (Pr. 882 to Pr. 886) is used.
  • Set the Pr. 22 Stall prevention operation level correctly.
E.OV2

Regenerative overvoltage trip during constant speed 		Cause:
  • Check for sudden load change.
  • Check that the setting of Pr. 22 Stall prevention operation level is not too small.

Remedy:
  • Keep load stable.
  • Check that regeneration avoidance function (Pr. 882 to Pr. 886) is used.
  • Use the brake resistor or brake unit as required.
  • Set the Pr. 22 Stall prevention operation level correctly.
E.OV3

Regenerative overvoltage trip during deceleration or stop 		Cause:
  • Check for sudden speed reduction.

Remedy:
  • Increase the deceleration time (Set the deceleration time which matches the moment of inertia of the load).
  • Longer the brake cycle.
  • Use regeneration avoidance function (Pr. 882 to Pr. 886).
  • Use the brake resistor or brake unit as required.
E.THT

Inverter overload trip (electronic thermal relay function) 		Cause:
  • Check that acceleration/deceleration time is not too short.
  • Check that torque boost setting is not too large (small).
  • Check that load pattern selection setting is appropriate for the load pattern of the using machine.
  • Check the motor for use under overload.
  • Check for too high surrounding air temperature.

Remedy:
  • Increase acceleration/deceleration time.
  • Adjust the torque boost setting.
  • Set the load pattern selection setting according to the load pattern of the using machine.
  • Reduce the load weight.
  • Set the surrounding air temperature to within the specifications.
E.THM

Motor overload trip (electronic thermal relay function) 		Cause:
  • Check the motor for use under overload.
  • Check that the setting of Pr. 71 Applied motor for motor selection is correct.
  • Check that stall prevention operation setting is correct.

Remedy:
  • Reduce the load weight.
  • For a constant-torque motor, set the constant-torque motor in Pr. 71 Applied motor.
  • Check that stall prevention operation setting is correct.
E.FIN

Heatsink overheat 		Cause:
  • Check for too high surrounding air temperature.
  • Check for heatsink clogging.
  • Check that the cooling fan is not stopped.

Remedy:
  • Set the surrounding air temperature to within the specifications.
  • Clean the heatsink.
  • Replace the cooling fan.
E.ILF

Input phase loss 		Cause:
  • Check for a break in the cable for the three-phase power supply input.
  • Check that phase-to-phase voltage of the three-phase power input is not largely unbalanced.

Remedy:
  • Wire the cables properly.
  • Repair a break portion in the cable.
  • Check the Pr. 872 Input phase loss protection selection setting.
  • Set Pr. 872 = "0" (without input phase loss protection) when three-phase input voltage is largely unbalanced.
E.OLT

Stall prevention stop		 Cause:
The output frequency has fallen to 1Hz by stall prevention operation and remained for 3s. Motor used under overload.

Remedy:
  • Check the motor for use under overload.
  • Reduce the load weight.
  • Check the Pr. 22 Stall prevention operation level setting.
E.BE

Brake transistor alarm detection		 Cause:
Large regenerative energy from the motor caused a brake transistor alarm. Inverter trips.

Remedy:
  • Reduce the load inertia.
  • Check that the frequency of using the brake is proper.
  • Replace the inverter (if transistor is damaged).
  • Note: Inverter must be powered OFF immediately.
E.GF

Output side earth (ground) fault overcurrent at start		 Cause:
Earth (ground) fault overcurrent flows at start due to an earth fault on the inverter's output side.

Remedy:
  • Check for a ground fault in the motor and connection cable.
  • Remedy the ground fault portion.
E.LF

Output phase loss		 Cause:
One of the three phases (U, V, W) on the output side is lost. Motor capacity smaller than inverter. Wiring issue.

Remedy:
  • Check the wiring and ensure motor is normal.
  • Wire the cables properly.
  • Check the Pr. 251 Output phase loss protection selection setting.
E.OP1

Communication option fault		 Cause:
Communication line error during CC-Link communication. Break in cable, wrong length, or terminator issue.

Remedy:
  • Refer to "Operation status indication LEDs" and perform appropriate countermeasures.
  • Check the connection of the CC-Link dedicated cable.
  • Check that CC-Link cables are within specified length.
  • Turn ON the built-in terminating resistor or attach the connector plug properly.
E.OPT

Option fault		 Cause:
Communication option is connected while Pr. 296 = "0 or 100" (Password lock activated).

Remedy:
  • Set Pr. 296 ≠ "0,100" to apply password lock when installing communication option.
  • If problem persists, contact sales representative.
E. 1

Option fault		 Cause:
Excessive noise around the inverter or switch for manufacturer setting has been changed.

Remedy:
  • Take measures against noises if devices are producing excess electrical noise.
  • Return the switch position for the manufacturer setting to the initial status.
E.PE

Parameter storage device fault (control circuit board)		 Cause:
Fault occurred in the parameter stored (EEPROM fault). Too many parameter write times.

Remedy:
  • If performing parameter write frequently via communication, set "1" in Pr. 342 to enable RAM write.
  • Contact your sales representative.
E.PE2

Internal board fault		 Cause:
Combination of the control board and the main circuit board is wrong.

Remedy:
  • Please contact your sales representative.
E.RET

Retry count excess		 Cause:
Operation cannot be resumed within the number of retries set (Pr. 67).

Remedy:
  • Find the cause of fault occurrence.
  • Eliminate the cause of the error preceding this error indication.
E. 5 / E. 6 / E. 7 / E.CPU

CPU fault		 Cause:
Communication fault of the built-in CPU occurs. Excess electrical noise or short between terminals PC and SD.

Remedy:
  • Take measures against noises.
  • Check connection between terminals PC and SD.
  • Please contact your sales representative.
E.MB4 to 7

Brake sequence fault		 Cause:
Sequence error occurred during use of the brake sequence function.

Remedy:
  • Check the set parameters and perform wiring properly.
E.IOH

Inrush current limit circuit fault		 Cause:
Resistor of inrush current limit circuit overheated due to frequent power ON/OFF.

Remedy:
  • Configure a circuit where frequent power ON/OFF is not repeated.
  • If problem persists, contact sales representative.
E.USB

USB communication fault		 Cause:
Communication broken during the time set in Pr. 548. Cable issue or timeout setting.

Remedy:
  • Check the USB communication cable.
  • Increase the Pr. 548 setting or change to 9999.
E.SAF

Safety circuit fault		 Cause:
Safety circuit malfunctioning. Lines between S1/PC or S2/PC opened. 24V power startup time > 500ms.

Remedy:
  • If safety function not used: Short across S1-PC and S2-PC.
  • If used: Check wiring and safety relay module.
  • Set the start-up time of the 24V external power supply to be within 500ms.
E. 13

Internal circuit fault		 Cause:
An internal circuit fault occurred.

Remedy:
  • Please contact your sales representative.
 

How to Read FR-E700 Faults via USB & Keypad

The FR-E700 modernized the compact drive market by adding direct USB connectivity. In 2026, troubleshooting is streamlined using these tools:

  • Built-in USB Port: Behind the front cover, the FR-E700 features a USB Mini-B port. This allows you to connect a standard USB cable directly to your PC without expensive RS-485 converters.
  • FR-Configurator2 (PC Software): By connecting via USB, you can use the software’s “Diagnosis” tool to view the “Fault History.” This displays not just the code, but the output frequency, current, and voltage at the exact moment of the trip, which is critical for identifying mechanical jams.
  • Integrated Digital Dial (PU): The drive face features a scroll wheel.
    • When an “E.” code appears, press the MODE button to see the fault history.
    • The dial allows you to toggle between the fault code and the amp draw at the time of the fault.

Frequently Asked Questions (FAQ)

Q: What is the difference between E.OC1 and E.OC3?

A: Both indicate Overcurrent (the most common fault), but the timing differs:

  • E.OC1 (During Accel): Indicates a short circuit, ground fault, or start-up jam. Check motor insulation and mechanical load.
  • E.OC3 (During Decel): Indicates the motor is regenerating energy too fast. You likely need to increase the deceleration time (Pr. 8) or add a braking resistor.

Q: How do I reset a Mitsubishi FR-E700 fault?

A:

  1. Press the STOP/RESET button on the integrated keypad.
  2. Short the RES terminal to SD (Sink logic) or PC (Source logic) for >0.1 seconds.
  3. Power cycle the drive (wait for the display to go dark).

Q: What does “E.THM” (Motor Overload) mean?

A: The drive’s electronic thermal relay has calculated that the motor is overheating.

  • Check if the motor fan is blocked.
  • Verify the Electronic Thermal O/L Relay setting (Pr. 9) matches the motor nameplate amps.
  • Reduce the load or install a motor with forced ventilation if running at low speeds.

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