Complete reference guide for Mitsubishi FR-F700P fault codes. Learn to interpret E. error codes, use FR Configurator for diagnostics, and troubleshoot trips on your fan and pump drives.

FR-F700P Fault Codes Reference Table

Below is the complete reference list for identifying specific inverter alarms and warnings:

Mitsubishi FR-F700P Fault Codes List

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: Attempted parameter setting when Pr. 77 is set to disable writing. Frequency jump setting range overlapped. Adjustable 5 points V/F settings overlapped. PU and inverter communication error. IPM parameter initialization attempted while Pr.72 = "25". Remedy: Check the setting of Pr. 77 Parameter write selection. Check the settings of Pr. 31 to 36 (frequency jump). Check the settings of Pr. 100 to Pr. 109 (Adjustable 5 points V/F). Check the connection of the PU and inverter. Check the Pr.72 PWM frequency selection setting.
Er2 Write error during operation	Cause: Parameter writing was performed during operation while Pr. 77 is not set to "2" and STF (STR) is ON. Remedy: Set "2" in Pr. 77. Or, stop the operation and then make parameter setting.
Er3 Calibration error	Cause: Analog input bias and gain calibration values are too close. Remedy: Check the settings of C3, C4, C6 and C7 (calibration functions).
Er4 Mode designation error	Cause: Attempted parameter setting in NET operation mode when Pr. 77 is not "2". Parameter write performed when command source is not at the operation panel. Remedy: Set operation mode to "PU operation mode", then make setting. Set "2" in Pr. 77, then make setting. Set Pr.551 = "2 (initial setting)".
rE1 Parameter read error	Cause: An error occurred in the EEPROM on the operation panel side during parameter copy reading. Remedy: Make parameter copy again. Check for an operation panel (FR-DU07) failure.
rE2 Parameter write error	Cause: Attempted parameter copy write during operation. EEPROM error on operation panel during parameter copy writing. Remedy: Stop the operation, then make parameter copy again. Check for an operation panel (FR-DU07) failure.
rE3 Parameter verification error	Cause: Data on the operation panel side and inverter side are different. EEPROM error on operation panel during verification. Remedy: Press [SET] to continue verification. Make parameter verification again. Check for an operation panel (FR-DU07) failure.
rE4 Model error	Cause: A different model was used for parameter writing/verification. Parameter copy write stopped after parameter copy read stopped. Remedy: Use the same model (FR-F700(P) series) for parameter copy/verification. Perform parameter copy read again.
Err. Error / Reset Signal	Cause: The RES signal is ON. Connection fault between PU and inverter. Voltage drops in the inverter's input side. Control circuit power and main circuit power connected to separate sources (timing issue). Remedy: Turn OFF the RES signal. Check the connection of PU and the inverter. Check the voltage on the inverter's input side.
OL Stall prevention (overcurrent)	Cause: The output current of the inverter exceeded the stall prevention operation level (Pr. 22). This stops frequency increase (accel) or decreases frequency (decel/constant speed) to prevent overcurrent trip. Remedy: Increase/Decrease Pr. 0 Torque boost value by 1%. Set larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time. Reduce load weight. Try Simple magnetic flux vector control. Adjust Pr. 13 Starting frequency or Pr. 14 Load pattern. Set stall prevention operation current in Pr. 22 (Initial 120%).
oL Stall prevention (overvoltage)	Cause: Regenerative energy of the motor became excessive (during deceleration). The inverter stops frequency decrease to prevent overvoltage trip. Remedy: Increase the deceleration time using Pr. 8 Deceleration time. Check if regeneration avoidance function (Pr. 882) is being used.
PS PU stop	Cause: Stop with [STOP/RESET] key of PU is set in Pr. 75. Remedy: Turn the start signal OFF and release with [PU/EXT].
RB Regenerative brake prealarm Appears if the regenerative brake duty reaches or exceeds 85% of the Pr. 70 setting. If it reaches 100%, a regenerative overvoltage (E.OV_) occurs.	Cause: Check that the brake resistor duty is not high. Check that the Pr. 30 Regenerative function selection and Pr. 70 Special regenerative brake duty values are correct. Remedy: Increase the deceleration time. Check the Pr. 30 and Pr. 70 values.
TH Electronic thermal relay function prealarm Appears if the cumulative value of the Pr. 9 Electronic thermal O/L relay reaches or exceeds 85% of the preset level.	Cause: Check for large load or sudden acceleration. Is the Pr. 9 Electronic thermal O/L relay setting appropriate? Remedy: Reduce the load weight or the number of operation times. Set an appropriate value in Pr. 9 Electronic thermal O/L relay.
MT Maintenance signal output Indicates that the cumulative energization time of the inverter has reached a given time.	Cause: 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.
CP Parameter copy Appears when parameters are copied between models with capacities of 55K or lower and 75K or higher.	Cause: Resetting of Pr.9, Pr.30, Pr.51, Pr.52, Pr.54, Pr.56, Pr.57, Pr.70, Pr.72, Pr.80, Pr.90, Pr.158, Pr.190 to Pr.196, Pr.557 and Pr.893 is necessary. Remedy: Set the initial value in Pr. 989 Parameter copy alarm release.
FN Fan alarm Appears on the operation panel when the cooling fan stops due to a fault or different operation from the setting of Pr. 244.	Cause: Check the cooling fan for an alarm. Remedy: Check for fan failure. Please contact your sales representative.
E.OC1 Overcurrent trip during acceleration When the inverter output current reaches or exceeds approximately 170% of the rated current during acceleration.	Cause: Check for sudden acceleration. Check that the downward acceleration time is not long in vertical lift application. Check for output short circuit. Check that the Pr. 3 Base frequency setting is not 60Hz when motor 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 the regeneration is not performed frequently. Check that the inverter capacity matches with the motor capacity. Remedy: Increase the acceleration time. Shorten the downward acceleration time in vertical lift application. Check the wiring to make sure that output short circuit does not occur. Set the Pr. 3 Base frequency to 50Hz. Lower the setting of stall prevention operation level. Activate the fast-response current limit operation. Choose inverter and motor capacities that match.
E.OC2 Overcurrent trip during constant speed When the inverter output current reaches or exceeds approximately 170% of the rated current during constant speed operation.	Cause: Check for sudden load change. Check for output short circuit. Check if the stall prevention operation level is set too high. Check if the fast-response current limit operation is disabled. Check that the inverter capacity matches with the motor capacity. Remedy: Keep load stable. Check the wiring to avoid output short circuit. Lower the setting of stall prevention operation level. Activate the fast-response current limit operation. Choose inverter and motor capacities that match.
E.OC3 Overcurrent trip during deceleration or stop When the inverter output current reaches or exceeds approximately 170% of the rated current during deceleration or stop.	Cause: Check for sudden speed reduction. Check for output short circuit. 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. Check that the inverter capacity matches with the motor capacity. Remedy: Increase the deceleration time. Check the wiring to avoid output short circuit. Check the mechanical brake operation. Lower the setting of stall prevention operation level. Activate the fast-response current limit operation. Choose inverter and motor capacities that match.
E.OV1 Regenerative overvoltage trip during acceleration If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value.	Cause: Check for too slow acceleration (e.g. during descending acceleration with lifting load). Check if Pr. 22 Stall prevention operation level is set too low like the no-load current. Remedy: Decrease the acceleration time. Use regeneration avoidance function (Pr. 882 to Pr. 886). Set a value larger than the no load current in Pr. 22 Stall prevention operation level.
E.OV2 Regenerative overvoltage trip during constant speed If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value.	Cause: Check for sudden load change. Check if Pr. 22 Stall prevention operation level is set too low like the no-load current. Remedy: Keep load stable. Use regeneration avoidance function (Pr. 882 to Pr. 886). Use the brake unit or power regeneration common converter (FR-CV) as required. Set a value larger than the no load current in Pr. 22 Stall prevention operation level.
E.OV3 Regenerative overvoltage trip during deceleration or stop If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value.	Cause: Check for sudden speed reduction. Remedy: Increase the deceleration time (match moment of inertia of load). Longer the brake cycle. Use regeneration avoidance function (Pr. 882 to Pr. 886). Use the brake unit or power regeneration common converter (FR-CV) as required.
E.THT Inv. Overload	Cause: Inverter overload trip (electronic thermal relay function). If a current not less than 120% of the rated output current flows and overcurrent trip does not occur (170% or less), the electronic thermal relay activates to stop the inverter. Check points: Check that acceleration/deceleration time is not too short. Check that Pr. 0 Torque boost setting is not too large. Check that Pr. 14 Load pattern selection is appropriate. Check the motor for use under overload. Remedy: Increase acceleration/deceleration time. Adjust the Pr. 0 Torque boost setting. Set the Pr. 14 Load pattern selection setting according to the load pattern. Reduce the load weight.
E.THM Motor Overload	Cause: Motor overload trip (electronic thermal relay function). The electronic thermal relay detects motor overheat due to overload or reduced cooling capability during constant-speed operation. Check points: Check the motor for use under overload. Check that the setting of Pr. 71 Applied motor 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. Check that stall prevention operation setting is correct.
E.FIN H/Sink O/Temp	Cause: Heatsink overheat. If the heatsink overheats, the temperature sensor is actuated to stop the inverter output. Check points: Check for too high surrounding air temperature. Check for heatsink clogging. Check that the cooling fan is stopped. Remedy: Set the surrounding air temperature to within the specifications. Clean the heatsink. Replace the cooling fan.
E.IPF Inst. Pwr. Loss	Cause: Instantaneous power failure. If a power failure occurs for longer than 15ms, the instantaneous power failure protective function is activated. Check points: Find the cause of instantaneous power failure occurrence. Remedy: Remedy the instantaneous power failure. Prepare a backup power supply. Set the function of automatic restart after instantaneous power failure (Pr. 57).
E.BE Br. Cct. Fault	Cause: Brake transistor alarm detection/internal circuit fault. Stops output if a fault occurs in the brake circuit (e.g., damaged brake transistors). Check points: Reduce the load inertia. Check that the frequency of using the brake is proper. Check that the brake resistor selected is correct. Remedy: For 75K or higher: Replace the brake unit. For 55K or lower: Replace the inverter.
E.UVT Under Voltage	Cause: If the power supply voltage decreases, the control circuit will not perform normal functions. Stops inverter if voltage drops below about 150V (200V class) or 300V (400V class). Also activates if jumper is missing across P/+ and P1. Check points: Check for start of large-capacity motor. Check that a jumper or DC reactor is connected across P/+ and P1. Remedy: Check the power supply system equipment. Connect a jumper or DC reactor across terminals P/+ and P1. If problem persists, contact sales representative.
E.ILF Input phase loss	Cause: Input phase loss. Output when one phase of the three-phase power input is lost (valid when Pr. 872 = 1). Check points: Check for a break in the cable for the three-phase power supply input. Remedy: Wire the cables properly. Repair a break portion in the cable. Check the Pr. 872 setting.
E.OLT Stall Prev STP	Cause: Stall prevention stop. If frequency falls to 0.5Hz (1.5Hz under IPM) by stall prevention and remains for 3s, E.OLT appears. Check points: Check the motor for use under overload. Check that a motor is connected during IPM motor control. Remedy: Reduce the load weight. Check the connection of the IPM motor. Set the IPM motor test operation.
E.SOT Motor step out	Cause: Loss of synchronism detection. Stops output when operation is not synchronized (IPM motor control only). Check points: Check that the IPM motor is not driven overloaded. Check if start command is given while IPM motor is coasting. Check if a motor other than IPM motor is driven. Remedy: Set the acceleration time longer. Reduce the load. If restarting during coasting, adjust Pr. 57 or select automatic restart.
E.GF Ground Fault	Cause: Output side earth (ground) fault overcurrent. Stops inverter if earth fault occurs on output side. Check points: Check for an earth (ground) fault in the motor and connection cable. Remedy: Remedy the earth (ground) fault portion.
E.LF Output phase loss	Cause: Output phase loss. Stops inverter if one of the three phases (U, V, W) on the output side is lost. Check points: Check the wiring. Check that motor capacity is not smaller than inverter. Check if start command is given while coasting. Remedy: Wire the cables properly. Choose inverter and motor capacities that match. Use automatic restart after instantaneous power failure.
E.OHT OH Fault	Cause: External thermal relay operation. External or internal temperature relay switches ON (contacts open). Check points: Check for motor overheating. Check that the value of 7 (OH signal) is set correctly in Pr. 178 to Pr. 189. Remedy: Reduce the load and operating duty. Note: Even if relay resets, inverter will not restart unless reset.
E.PTC PTC activated	Cause: PTC thermistor operation. Motor overheat status detected for 10s or more by external PTC thermistor connected to terminal AU. Check points: Check connection between PTC thermistor switch and thermal relay protector. Check motor for operation under overload. Is valid setting (=63) selected in Pr. 184? Remedy: Reduce the load weight.
E.OPT Option Fault	Cause: Option fault. AC power connected to wrong terminals, plug-in option switch changed, or communication option connected while password locked. Check points: Check that AC power is not connected to output terminals. Check if password lock is activated. Remedy: Check parameter Pr. 30 setting and wiring. Return switch for manufacturer setting to initial status. Apply password lock when installing communication option. Contact sales representative if problem persists.
E.OP1 Communication option fault	Cause: Stops the inverter output when a communication line fault occurs in the communication option. Check for a wrong option function setting and operation. Check that the plug-in option is plugged into the connector securely. Check for a break in the communication cable. Check that the terminating resistor is fitted properly. Remedy: Check the option function setting, etc. Connect the plug-in option securely. Check the connection of communication cable.
E.1 Option fault	Cause: Stops the inverter output if a contact fault or the like of the connector between the inverter and communication option occurs. Appears when the switch for the manufacturer setting of the plug-in option is changed. Check that the plug-in option is plugged into the connector securely. Check for excess electrical noises around the inverter. Remedy: Connect the plug-in option securely. Take measures against noises if there are devices producing excess electrical noises around the inverter. If the problem still persists, please contact your sales representative. Return the switch position for the manufacturer setting to the initial status.
E.PE Parameter storage device fault (control circuit board)	Cause: Trips when a fault occurred in the parameter stored (EEPROM failure). Check for too many number of parameter write times. Remedy: Please contact your sales representative. When performing parameter write frequently for communication purposes, set "1" in Pr. 342 to enable RAM write. Note that powering OFF returns the inverter to the status before RAM write.
E.PE2 Parameter storage device fault (main circuit board)	Cause: Trips when a fault occurred in the parameter stored (EEPROM failure). Remedy: Please contact your sales representative.
E.PUE PU disconnection	Cause: This function stops the inverter output if communication between the inverter and PU is suspended (disconnected). This function stops the inverter output when communication errors occurred consecutively for more than permissible number of retries. This function stops the inverter output if communication is broken for the period of time set in Pr. 122. Check that the FR-DU07 or parameter unit is fitted tightly. Check the Pr. 75 setting. Remedy: Fit the FR-DU07 or parameter unit (FR-PU04/FR-PU07) securely.
E.RET Retry count excess	Cause: If operation cannot be resumed properly within the number of retries set, this function trips the inverter. Find the cause of fault occurrence. Remedy: Eliminate the cause of the fault preceding this error indication.
E.5 / E.6 / E.7 / E.CPU CPU fault	Cause: Stops the inverter output if the communication fault of the built-in CPU occurs. Check for devices producing excess electrical noises around the inverter. Remedy: Take measures against noises if there are devices producing excess electrical noises around the inverter. Please contact your sales representative.
E.CTE Operation panel / RS-485 power supply short circuit	Cause: When the operation panel power supply (PU connector) is shorted, or internal power supply for RS-485 terminals are shorted, this function shuts off the power output. Check for a short circuit in the PU connector cable. Check that the RS-485 terminals are connected correctly. Remedy: Check the PU and cable. Check the connection of the RS-485 terminals. To reset, enter the RES signal or switch power OFF, then ON again.
E.P24 24VDC power output short circuit	Cause: When the 24VDC power output from the PC terminal is shorted, this function shuts off the power output. All external contact inputs switch OFF. Check for a short circuit in the PC terminal output. Remedy: Remedy the earth (ground) fault portion. Reset via operation panel or power cycle.
E.CDO Output current detection value exceeded	Cause: This function stops the inverter output when the output current exceeds the setting of Pr.150 or falls below Pr.152. Check the settings of Pr. 150, Pr. 151, Pr. 152, Pr. 153, Pr. 166, Pr. 167. Remedy: Review and adjust parameter settings related to Output Current Detection (Refer to manual page 146).
E.IOH Inrush current limit circuit fault	Cause: Trips when the resistor of the inrush current limit circuit overheats. Check that frequent power ON/OFF is not repeated. Check that no meltdown is found in the input side fuse (5A). Check that the inrush current suppression circuit contactor is not damaged. Remedy: Configure a circuit where frequent power ON/OFF is not repeated. If the problem still persists after taking the above measure, please contact your sales representative.
E.SER Communication fault (inverter)	Cause: This function stops the inverter output when communication error occurs consecutively for more than permissible retry count (Pr. 335) or communication is broken for time set in Pr. 336. Check the RS-485 terminal wiring. Remedy: Perform wiring of the RS-485 terminals properly.
E.AIE Analog input fault	Cause: Stops the inverter output when a 30mA or higher current or a 7.5V or higher voltage is input to terminal 2 or terminal 4 while specific input selections are active. Check the setting of Pr. 73 Analog input selection and Pr. 267 Terminal 4 input selection. Remedy: Either give a frequency command by current input or set Pr. 73 or Pr. 267 to voltage input.
E.PID PID signal fault	Cause: If any of PID upper limit (FUP), PID lower limit (FDN), and PID deviation limit (Y48) turns ON during PID control, inverter shuts off the output. Check if the measured PID value is greater than the upper limit (Pr.131) or smaller than the lower limit (Pr.132). Check if the absolute PID deviation value is greater than the limit value (Pr.553). Remedy: Make correct settings for Pr.131, Pr.132, and Pr.553.
E.13 Internal circuit fault	Cause: Trips when an internal circuit error occurred. Remedy: Please contact your sales representative.

 

How to Read FR-F700P Faults via FR Configurator

To get the most accurate diagnostic data in 2026, connect your PC to the inverter using the FR Configurator2 software via the USB or RS-485 port. This provides advanced analysis beyond the keypad display.

• Alarm History: The FR-F700P stores the last 8 alarm records. Using the software, you can see the sequence of failures to determine if the issue is recurring.
• Status Monitoring: Unlike a simple code display, the software shows the status of input/output terminals and the exact frequency at the moment the trip occurred.
• Trace Function: Similar to a flight recorder, the trace function captures waveform data (current, voltage, and speed) immediately before and after the protection function is activated, allowing for precise root-cause analysis.

Frequently Asked Questions (FAQ)

Q: What is the difference between a Minor Fault (Warning) and a Major Fault?
A: A Warning (such as ‘OL’ for Overload or ‘PS’ for PU Stop) flashes on the screen but typically allows the motor to continue running or ramp down safely. A Major Fault (indicated by codes starting with ‘E.’, such as E.OV1) immediately shuts off the inverter output to protect internal components.

Q: How do I reset a Mitsubishi FR-F700P fault?
A: You can reset the drive by pressing the STOP/RESET button on the operation panel, switching the power off and on again, or by turning on the specific “RES” (Reset) signal at the control circuit terminal.

Q: Where is the fault history stored?
A: The fault history is retained in the inverter’s EEPROM. You can view the last 8 faults directly on the keypad by navigating to the “Alarm History” menu, or view detailed diagnostics via the FR Configurator software.