Access the complete reference guide for Mitsubishi FR-D700G micro drive fault codes. Learn to diagnose E.THT overloads, use FR Configurator2, and interpret LED warnings.

Mitsubishi FR-D700G Fault Codes Reference Table

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

Mitsubishi FR-D700G Fault Codes List

Fault Code and Meaning	Cause and Remedy
Hold Operation panel lock	Cause: Operation has been attempted during the operation panel lock. Remedy: Press MODE for 2s to release lock.
Locd Password locked	Cause: Reading/writing of a password-restricted parameter has been attempted. Remedy: Enter the password in Pr. 297 Password lock/unlock to unlock the password function before operating.
Er1 Write disable error	Cause: Parameter setting has been attempted although parameter writing is set to be disabled. Overlapping range has been set for the speed jump. PU and the drive unit cannot make normal communication. Remedy: Check the setting of Pr. 77 Parameter write selection. Check the setting of Pr. 31 to Pr. 36 (speed jump). Check the connection of PU and the drive unit.
Er2 Write error during operation	Cause: Parameter writing has been attempted while a value other than "2" is set in Pr. 77 Parameter write selection and the STF (STR) is ON. Remedy: Set "2" in Pr. 77 Parameter write selection. After stopping the operation, set parameters.
Er3 Calibration error	Cause: Analog input bias and gain calibration values have been set too close. Remedy: Check the settings of calibration parameters C3, C4, C6 and C7 (calibration functions).
Er4 Mode designation error	Cause: Parameter setting has been attempted in the External or NET operation mode when Pr. 77 Parameter write selection is not "2". Parameter writing has been attempted when the command source is not at the operation panel. Remedy: After setting the operation mode to the "PU operation mode", set parameters. Set "2" in Pr. 77 Parameter write selection. Remove the parameter unit (FR-PU07), then set the Pr. 551 PU mode operation command source selection = "9999 (initial setting)." Set Pr. 551 PU mode operation command source selection = "4."
Err. Drive unit reset	Cause: The reset signal (RES signal) is ON (drive unit output is shutoff). Remedy: Turn OFF the reset command.
OL Stall prevention (overcurrent)	Cause: The overcurrent stall prevention has been activated. Remedy: Set Pr.7 Acceleration time and Pr.8 Deceleration time longer. Reduce the load. Set the stall prevention operation current in Pr. 22 Stall prevention operation level. Increase the stall prevention operation level with Pr. 22 or disable stall prevention with Pr. 156. Check the connection of the PM motor.
oL Stall prevention (overvoltage)	Cause: The overvoltage stall prevention function or the regeneration avoidance function has been activated. Remedy: Set the deceleration time longer.
rb Regenerative brake pre-alarm	Cause: The regenerative brake duty has reached 85% of the Pr. 70 Special regenerative brake duty setting or higher. Remedy: Set the deceleration time longer. Check the Pr.30 Regenerative function selection and Pr. 70 Special regenerative brake duty settings.
TH Electronic thermal relay function pre-alarm	Cause: The cumulative value of the electronic thermal O/L relay has reached 85% of the Pr. 9 Electronic thermal O/L relay setting or higher. Remedy: Reduce the load and frequency of operation. Set an appropriate value in Pr. 9 Electronic thermal O/L relay.
PS PU stop	Cause: STOP/RESET on the operation panel has been pressed during the External operation. Remedy: Turn the start signal OFF and release with PU/EXT.
MT Maintenance signal output	Cause: The cumulative energization time has exceeded the maintenance output timer set value. Remedy: Setting "0" in Pr. 503 Maintenance timer erases the signal.
Uv Undervoltage	Cause: The voltage at the main circuit power has been lowered. Remedy: Investigate the devices on the power supply line such as the power supply itself.
SA Safety Stop (SA)	Cause: The shorting wire across the terminals S1 and SC or the terminals S2 and SC is disconnected. Remedy: Short across the terminals S1 and SC and the terminals S2 and SC with shortening wires.
Fn Fan alarm	Cause: The cooling fan is at a standstill although it is required to be operated. Cooling fan speed has decelerated. Remedy: Check for fan failure. Please contact your sales representative.
E.OC1 Overcurrent trip during acceleration	Cause: Overcurrent has occurred during acceleration. Remedy: Set the acceleration time longer. (Shorten the downward acceleration time in vertical lift application.) If "E.OC1" always appears at start, disconnect the motor once and restart the drive unit. If it still appears, contact sales representative. Check the wiring for output short circuit and ground fault. Change the setting to enable the stall prevention operation (Pr.156). Lower the stall prevention operation level. Choose drive unit and motor capacities that match. If the motor is coasting, stop the motor, then input a start command.
E.OC2 Overcurrent trip during constant speed	Cause: Overcurrent has occurred during constant speed operation. Remedy: Keep the load stable. Check the wiring to avoid output short circuit or ground fault. Change the setting to enable the stall prevention operation (Pr.156). Lower the stall prevention operation level. Choose drive unit and motor capacities that match. If the motor is coasting, stop the motor, then input a start command.
E.OC3 Overcurrent trip during deceleration or stop	Cause: Overcurrent has occurred during deceleration or at a stop. Remedy: Set the deceleration time longer. Check the wiring to avoid output short circuit or ground fault. Check if the mechanical brake is set to be activated too early. Change the setting to enable the stall prevention operation (Pr.156). Lower the stall prevention operation level. Choose drive unit and motor capacities that match. If the motor is coasting, stop the motor, then input a start command.
E.OV1 Regenerative overvoltage trip during acceleration	Cause: Overvoltage has occurred during acceleration. Remedy: Set the acceleration time shorter. Use the regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). Set the Pr. 22 Stall prevention operation level correctly.
E.OV2 Regenerative overvoltage trip during constant speed	Cause: Overvoltage has occurred during constant speed operation. Remedy: Keep the load stable. Use the regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required. Set the Pr. 22 Stall prevention operation level correctly.
E.OV3 Regenerative overvoltage trip during deceleration or stop	Cause: Overvoltage has occurred during deceleration or at a stop. Remedy: Set the deceleration time longer. (Set the deceleration time which matches the moment of inertia of the load.) Make the brake cycle longer. Use the regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
E.THM Drive unit overload trip (electronic thermal O/L relay function)	Cause: The electronic thermal relay function for drive unit element protection has been activated. Remedy: Set the acceleration time longer. Adjust the Pr.785 PM control torque boost and Pr.795 DC brake torque boost settings. Reduce the load. Set the surrounding air temperature to within the specifications.
E.THT Motor overload trip (electronic thermal O/L relay function)	Cause: The electronic thermal relay function for motor protection has been activated. Remedy: Reduce the load. Adjust the Pr.785 PM control torque boost and Pr.795 DC brake torque boost settings. Set the stall prevention operation level accordingly.
E.FIN Heatsink overheat	Cause: The heatsink has overheated. Remedy: Set the surrounding air temperature to within the specifications. Clean the heatsink. Replace the cooling fan.
E.ILF Input phase loss	Cause: One of the three phases on the drive unit input side has been lost. It may also appear if phase-to-phase voltage of the three-phase power input has become 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 Input phase loss protection selection = "0" (without input phase loss protection) when three-phase input voltage is largely unbalanced.
E.OLT Stall prevention stop	Cause: The rotation speed has dropped to 15r/min as a result of deceleration due to the excess motor load. Remedy: Reduce the load. (Check the Pr. 22 Stall prevention operation level setting.)
E.SOT Loss of synchronism detection	Cause: Operation has gone out of synchronism or operation was performed without connecting a motor. Remedy: Set the acceleration time longer. Reduce the load. If the motor is coasting, stop the motor, then input a start command. Alternatively, use the automatic restart after instantaneous power failure/flying start function. According to the motor to be used, perform PM parameter initialization. When driving a motor other than the S-PM geared motor, perform offline auto tuning. Check the connection of the PM motor, or set the PM motor test operation.
E.BE Brake transistor alarm detection	Cause: A fault has occurred in the brake circuit, such as a brake transistor breakage. (In this case, the drive unit must be powered off immediately.) Remedy: Replace the drive unit.
E.GF Output side earth (ground) fault overcurrent at start	Cause: An earth (ground) fault has occurred on the drive unit's output side (detected only at a start). Remedy: Remedy the ground fault portion.
E.LF Output phase loss	Cause: One of the three phases (U, V, W) on the drive unit's output side (load side) has been lost during drive unit operation. Remedy: Wire the cables properly. If the motor is coasting, stop the motor, then input a start command.
E.OHT External thermal relay operation	Cause: The external thermal relay connected to the OH signal has been activated. Remedy: Reduce the load and operate less frequently. Even if the relay contacts are reset automatically, the drive unit will not restart unless it is reset.
E.PTC PTC thermistor operation	Cause: Resistance of the PTC thermistor connected between the terminal 2 and terminal 10 has reached the Pr.561 PTC thermistor protection level setting or higher. Remedy: Reduce the load.
E.PE Parameter storage device fault	Cause: Operation of the component where parameters are stored (control circuit board) has become abnormal. Remedy: Please contact your sales representative. When performing parameter writing frequently for communication purposes, set "1" in Pr. 342 Communication EEPROM write selection to enable RAM write. Note that powering OFF returns the drive unit to the status before RAM write.
E.PUE PU disconnection	Cause: A communication error has occurred between the PU and the drive unit, or the number of communication errors has exceeded the number of retries. Remedy: Connect the parameter unit cable securely. Check the communication data and communication settings. Increase the Pr. 122 PU communication check time interval setting. Or set "9999" (no communication check).
E.RET Retry count excess	Cause: Operation restart within the set number of retries has failed. Remedy: Eliminate the cause of the error preceding this error indication.
E.5 / E.CPU CPU fault	Cause: An error has occurred in the CPU and in the peripheral circuits. Remedy: Take measures against noises if there are devices producing excess electrical noises around the drive unit. If the situation does not improve after taking the above measure, please contact your sales representative.
E.CDO Output current detection value exceeded	Cause: Output current has exceeded the output current detection level that is set in the parameter. Remedy: Check the settings of Pr. 150 Output current detection level, Pr. 151 Output current detection signal delay time, Pr. 166 Output current detection signal retention time, and Pr. 167 Output current detection operation selection.
E.IOH Inrush current limit circuit fault	Cause: The resistor of the inrush current limit circuit has overheated. Remedy: Configure a circuit where frequent power ON/OFF is not repeated. If the situation does not improve after taking the above measure, please contact your sales representative.
E.AIE Analog input fault	Cause: A voltage (current) has been input to terminal 4 when the setting in Pr. 267 Terminal 4 input selection and the setting of voltage/current input switch are different. Remedy: Give a speed command by a current input or set Pr. 267 Terminal 4 input selection, and set the voltage/current input switch to voltage input.
E.OS Overspeed occurrence	Cause: The motor speed has exceeded the Pr. 374 Overspeed detection level. Remedy: Check that the Pr. 374 Overspeed detection level value is correct.
E.PID PID signal fault	Cause: PID upper limit (FUP), PID lower limit (FDN), or PID deviation limit (Y48) has turned ON. Remedy: Make correct settings for Pr.131 PID upper limit, Pr.132 PID lower limit, Pr. 553 PID deviation limit.
E.SAF Safety circuit fault	Cause: An internal circuit fault has occurred. Either the contact between terminals S1 and SC or terminals S2 and SC has opened. Remedy: Short across the terminals S1 and SC and the terminals S2 and SC with shortening wires. If faults other than the above appear, contact your sales representative.

 

How to Read FR-D700 Faults via LED & Software

Because the FR-D700 is a micro-drive, it does not have a large LCD screen. In 2026, efficient troubleshooting involves using the Digital Dial or connecting a PC:

• Integrated LED Panel: The drive features a 4-digit LED display and a “Digital Dial” (M-Dial).
  • E.xxx (Fault): The drive output is stopped. Example: E.THT (Thermal Overload).
  • Warning Mode: If the screen flashes codes like TH or PS while running, the drive is warning you of impending failure but has not tripped yet.
• FR Configurator2 (PC Software): Connect your PC via the PU port (using a specialized RS-485 to USB cable like the SC09). This software is essential for:
  • Fault History: Viewing the last 8 faults with volt/amp data at the time of the trip.
  • Life Check: The D700 series monitors the age of its own internal capacitors and Inrush Current Limit circuit. The software will alert you if the hardware is nearing its 10-year design life.

---

Frequently Asked Questions (FAQ)

Q: What is the difference between “E.THT” and “E.THM”?

A: Both refer to overload, but the source differs:

• E.THT (Inverter Thermal): The Drive itself is overheating. Check if the cooling fan is clogged or if the ambient temperature is too high.
• E.THM (Motor Thermal): The Motor is overheating (calculated electronically). Check if the load is too heavy or if the motor parameters (Pr. 9) are set incorrectly.

Q: How do I reset a Mitsubishi FR-D700 fault?

A:

1. Press the STOP/RESET button on the drive face.
2. Short the RES and SD terminals for at least 0.1 seconds.
3. Cycle the main power supply (wait for the LED display to turn off completely).

Q: Why is the “SA” or “Safety” LED on?

A: The FR-D700 features a “Safety Stop” function (S1/S2 terminals). If the bridge bar between S1-S2-PC is removed or your emergency stop circuit is open, the drive output is blocked by hardware, and the Safety Monitor LED will light up. This is not a parameter fault; it is a hardwired safety state.