Mitsubishi FR-E800 Fault Codes: Meanings & Checks

Quick answer

An FR-E800 that trips shuts off its output, sends the Fault (ALM) signal and shows E. and a short code on the operation panel – for example E.OC1. Warnings such as OLC, OLV, UV or TH and the FN fan alarm don't trip the inverter by themselves, but the manual says a warning leads to a fault if nothing is done. Find the code below, fix the cause, make sure the start signal is off, then reset with the STOP/RESET key, the RES input or a power cycle.

Jump to a code:

E.OC1
E.OC2
E.OC3
E.SCF
E.OV1
E.OV2
E.OV3
E.THT
E.THM
E.FIN
E.UVT
E.ILF
E.OLT
E.GF
E.LF
E.OHT
E.PTC
E.BE
E.SAF
E.PE
E.PE6
E.PUE
E.RET
E.CPU
E.5
E.6
E.7
E.IOH
E.AIE
E.EHR
E.OP1
OLC
OLV
UV
TH
SA
Cor
FN

Safety first: lock out and tag out the inverter and the machine before you open the inverter or touch the wiring, and follow Mitsubishi Electric's precautions in the manuals. The smoothing capacitors stay charged after power is removed: the Maintenance manual says to wait 10 minutes or longer; then a qualified person, with a properly rated meter checked on a known source before and after, confirms that the voltage between main circuit terminals P/+ and N/– is 30 V DC or less – a dark display doesn't mean it's safe. If the panel shows EV (the inverter runs on an external 24 V supply), switch that supply off too. Never bypass the safety stop inputs (S1, S2) or any other safety circuit, and never switch off a fault or raise the retry count to keep a machine running – the retry function restarts the motor by itself. Only qualified personnel should work on inverters, and any measurement on energized equipment follows your site's live-work and arc-flash rules.

Reading and resetting an FR-E800 fault

Note the code. The operation panel's fault history keeps the last ten faults, each with the output frequency, current and voltage and the energization time when it happened. Er.CL clears it.
Look it up in the table below or in the manual, and fix the cause first – a fault whose cause is still there comes straight back.
Reset it: turn the start signal off first – the manual warns that a reset with it on restarts the motor suddenly – then press STOP/RESET, turn on the RES signal for 0.1 s or more, or switch the power off and on. The IP67 model's panel has no STOP/RESET key.
Watch the restart. If the same code returns, go back through the checks before resetting again.

One Maintenance manual covers the FR-E800 standard, Ethernet, safety communication (SCE), IP67 and CC-Link (NC) models. Some codes apply only to certain models, motors or control methods (PM motors, vector control), and codes marked “Off in the initial setting” only appear once their function has been turned on.

Common FR-E800 fault codes

This list covers the codes technicians run into most often, not every code. The manual has the complete list and the full corrective actions.

Code	What it means	Likely causes	First checks
E.OC1Overcurrent trip during accelerationFault	Output current went over the trip level (about 230 % of rated current at the ND rating) while accelerating.	Acceleration too fast for the load A short on the output side Pr.3 [Base frequency] at 60 Hz for a 50 Hz motor, or a restart after a power loss, MRS or safety stop	Lengthen Pr.7 [Acceleration time] With power locked out, check the output wiring and the motor for a short If it trips at every start, the manual says to try with the motor disconnected, then contact your Mitsubishi sales representative
E.OC2Overcurrent trip during constant speedFault	Output current went over the trip level while running at a steady speed.	A sudden load change A short on the output side Stall prevention level too high, or the fast-response current limit turned off	Keep the load steady With power locked out, check the output wiring and the motor Lower the stall prevention level and turn on the fast-response current limit
E.OC3Overcurrent trip during deceleration or stopFault	Output current went over the trip level while slowing down or stopped.	Deceleration too fast A motor brake working too early A short on the output side	Lengthen Pr.8 [Deceleration time] Check the mechanical brake timing With power locked out, check the output wiring and the motor
E.SCFOutput short-circuitFaultOff in the initial setting	An output short circuit was found (only with Pr.521 = 1; otherwise it shows as E.OC1 to E.OC3).	A short between output phases, in the cable or in the motor	With power locked out, find and fix the short The manual says this one is reset by switching the power off
E.OV1Regenerative overvoltage trip during accelerationFault	Regenerated energy pushed the internal DC voltage too high while accelerating; a supply surge can do it too.	An overhauling load while accelerating slowly, such as lowering on a hoist Pr.22 [Stall prevention operation level] at or below the no-load current A restart after a power loss, MRS or safety stop	The manual suggests a shorter acceleration time here Use regeneration avoidance (Pr.882, Pr.883, Pr.885, Pr.886) Add a brake resistor, brake unit or FR-XC converter if needed
E.OV2Regenerative overvoltage trip during constant speedFault	Regenerated energy pushed the internal DC voltage too high at a steady speed.	A sudden load change Acceleration / deceleration times too short Stall prevention working often on a high-inertia load	Keep the load steady Use regeneration avoidance Add a brake resistor or brake unit if needed
E.OV3Regenerative overvoltage trip during deceleration or stopFault	Regenerated energy pushed the internal DC voltage too high while slowing down or stopped.	Deceleration too fast for the load's inertia Braking too often	Lengthen Pr.8 [Deceleration time] to suit the inertia Make the braking cycle longer, or use regeneration avoidance Add a brake resistor, brake unit or FR-XC converter if needed
E.THTInverter overload trip (electronic thermal relay function)Fault	The output transistors' thermal protection tripped; the manual gives the overload capacity as 150 % for 60 s.	Acceleration / deceleration too short Torque boost or load pattern set wrong Load too heavy	Lengthen the acceleration / deceleration times Check Pr.0 [Torque boost] and Pr.14 [Load pattern selection] Reduce the load; a reset clears the thermal count
E.THMMotor overload trip (electronic thermal relay function)Fault	The motor's electronic thermal protection tripped; the TH warning comes first, at 85 %.	Motor overloaded, or poor motor cooling at low speed Pr.71 [Applied motor] set wrong Several motors or a special motor on one inverter	Reduce the load and let the motor cool For a constant-torque motor, set it in Pr.71 For several or special motors the manual calls for external thermal relays
E.FINHeat sink overheatFault	The heat sink's temperature sensor tripped.	Surrounding air too hot A clogged heat sink A stopped cooling fan, or one fitted the wrong way	Keep the surrounding air within the rating With power locked out, clean the heat sink Check the fan (FN means it stopped) and its orientation
E.UVTUndervoltageFault	With a PM motor, supply dips made the motor coast and restart over and over.	Power failures or voltage drops Automatic restart after instantaneous power failure repeating	Read the DC bus on the panel first: Pr.52 = 8 shows the converter output voltage Checking the supply while it runs is live work for a qualified electrician, or use a power-quality recorder Look at the devices on the supply line
E.ILFInput phase lossFault	One of the three input phases was lost (only with Pr.872 = 1).	A broken input cable A blown fuse or an open breaker pole	With power locked out, check the input cables, terminals and fuses Checking the supply while it runs is live work for a qualified electrician, or use a power-quality recorder
E.OLTStall prevention stopFault	Stall prevention or the torque limit held the output at low speed for 3 seconds because of the load.	Motor overloaded or the machine jammed Pr.22, Pr.865 or Pr.874 set wrong No motor connected under PM sensorless vector control	With power locked out, check that the machine turns freely; reduce the load Check Pr.22 (V/F, magnetic flux) or Pr.865 and Pr.874 (vector control) Deal with any OLC or OLV warnings too
E.GFOutput side earth (ground) fault overcurrentFault	A ground fault on the output (load) side made the inverter shut off.	Damaged motor cable insulation A motor winding with a fault to ground	With power locked out, find and fix the grounded part Locked out, a qualified person disconnects the motor leads before an insulation check of the motor and cable (common practice) With Pr.249 = 2 an E.GF can be reset only by switching the power off
E.LFOutput phase lossFault	One of the output phases (U, V, W) was lost.	An open wire or a loose terminal to the motor A motor smaller than the inverter's capacity Starting a coasting PM motor	With power locked out, check the motor wiring end to end Use a motor that matches the inverter capacity
E.OHTExternal thermal relay operationFaultOff in the initial setting	A thermal relay or motor thermostat wired to the OH input opened.	The motor overheating OH assigned to the wrong input	Reduce the load and the operation duty Check the OH assignment (Pr.178 to Pr.184) A reset is needed even after the relay closes again
E.PTCPTC thermistor operationFaultOff in the initial setting	The motor's PTC thermistor on terminal 2 read above the Pr.561 level for the Pr.1016 time.	The motor overheating A loose thermistor connection	Reduce the load Check the thermistor wiring Check Pr.561 and Pr.1016
E.BEBrake transistor alarm detectionFault	A fault in the brake circuit, such as a damaged brake transistor.	Brake duty too high Too much load inertia	The manual says to shut off the inverter's power immediately Its remedy is replacing the inverter
E.SAFSafety circuit faultFault	A safety circuit fault, or the S1–PC or S2–PC connection opened while the safety stop is in use.	A fault in the safety relay module or its wiring A broken wire on S1, S2 or PC	Never jumper S1 or S2 on a machine that uses the safety stop function Check the S1 / S2 / PC wiring and the safety relay module On a safety communication (SCE) model, see its Functional Safety manual
E.PEParameter storage device fault (control circuit board)Fault	A fault in the stored parameters (the EEPROM) on the control board.	Too many parameter writes A firmware update that didn't finish	Reset the inverter For frequent writes over communication, Pr.342 = 1 writes to RAM only (lost at power-off) If it stays, the manual's remedy is contacting your Mitsubishi sales representative
E.PE6Internal storage device faultFault	Writing to the internal storage failed, for example because power went off during a parameter operation.	Power off during a parameter clear, copy or auto tuning Very frequent writes to the EEPROM	Check the power supply Read Pr.890 and follow the manual's steps for its value For frequent writes, Pr.342 = 1 writes to RAM only
E.PUEPU disconnectionFault	Communication with the PU, or RS-485 on the PU connector, was lost.	The PU cable unplugged while disconnected-PU detection is on Repeated communication errors or a timeout on RS-485	Reconnect the PU cable Check Pr.75 [Reset selection/disconnected PU detection/PU stop selection] Check Pr.121 and Pr.122
E.RETRetry count excessFaultOff in the initial setting	The retry function could not restart the inverter within the number of retries set in Pr.67.	The fault behind the retries is still there	Retry restarts the motor on its own: remove the start signal before working on the machine Find and fix the fault that came before this one Never raise the retry count (Pr.67) to ride over a fault
E.CPU / E.5 / E.6 / E.7CPU faultFault	A communication fault of the built-in CPU.	Electrical noise near the inverter An Ethernet cable not connected properly A wire between terminals PC and SD (E.6, E.7)	Deal with noise sources near the inverter Connect the Ethernet cable properly; remove any wire between PC and SD If it stays, the manual's remedy is contacting your Mitsubishi sales representative
E.IOHInrush current limit circuit faultFault	The inrush current limit resistor overheated.	Power switched on and off too often A blown 5 A fuse in the inrush contactor's supply circuit	Use a circuit that doesn't cycle the power often With power locked out, check that fuse If it stays, the manual's remedy is contacting your Mitsubishi sales representative
E.AIEAnalog input faultFault	Terminal 2 or 4, set for current input, got 30 mA or more or 7.5 V or more.	A voltage signal on an input set for current Pr.73, Pr.267 and the input switch mismatched	Keep the current under 30 mA Or set Pr.73, Pr.267 and the voltage / current switch to voltage input
E.EHREthernet communication faultFault	Ethernet communication was lost for the Pr.1432 time, or the network master stopped or timed out.	A broken or loose Ethernet cable Pr.1432 set too short Electrical noise	Check the Ethernet cable and connector Check Pr.1432 and the master's state Ground the cable shield to the enclosure near the inverter
E.OP1Communication option faultFault	A communication line error in the plug-in communication option.	A loose plug-in option A broken network cable A missing terminating resistor	Check the option's settings Seat the option and check the cables and terminating resistor If it stays, the manual's remedy is contacting your Mitsubishi sales representative
OLCStall prevention (overcurrent)Warning	Output current is over the stall prevention level, so the inverter holds or lowers the frequency.	Acceleration / deceleration too short or load too heavy Pr.0 [Torque boost] or Pr.13 set too high	Lengthen Pr.7 and Pr.8 Reduce the load; change Pr.0 in 1 % steps Check Pr.22 [Stall prevention operation level]
OLVStall prevention (overvoltage)Warning	Regenerated energy is too much, so the inverter pauses the deceleration to avoid an overvoltage trip.	A sudden speed reduction	Lengthen Pr.8 [Deceleration time] Check whether regeneration avoidance is in use
UVUndervoltageWarning	The supply fell to the undervoltage level for its voltage class; the output stays off until it recovers.	A low or dipping supply A lost phase or a loose supply connection	The Maintenance manual's levels: about 115, 230, 330 or 58 V AC for the 200, 400, 575 or 100 V class Under PM sensorless vector control the levels are about 156, 311, 448 or 78 V AC Read the DC bus on the panel first: Pr.52 = 8 shows the converter output voltage Checking the supply while it runs is live work for a qualified electrician, or use a power-quality recorder Look at the devices on the supply line
THElectronic thermal relay function pre-alarmWarning	The electronic thermal value reached 85 % of the Pr.9 setting; the inverter trips if it reaches the limit.	A heavy load or sudden acceleration Pr.9 [Electronic thermal O/L relay] set wrong	Reduce the load and how often it runs Check Pr.9 against the motor
SASafety stopWarning	The safety stop function is active and the output is shut off.	An emergency stop or safety device opened S1 / S2 A broken wire on S1, S2 or PC	Find which safety device opened and why before restarting Never jumper S1 or S2 to get a machine running If SA stays with both inputs conducting, the manual points to an internal failure
CorCorrosion warningWarning	The control board's corrosion level reached 3 (coated FR-E800 models with -60 at the end only).	A corrosive, damp or dirty environment	Improve the environment with filtering or ventilation The manual suggests considering an early replacement of the inverter
FNFan alarmAlarm	The cooling fan stopped, runs too slowly, or doesn't run the way Pr.244 sets it.	A failed fan A replacement fan fitted upside down	With power locked out, check that the fan is fitted the right way If FN stays with the fan fitted correctly, the manual says the fan may be faulty

The name is the manual's own name for the code; the code is what the operation panel shows. A warning or an alarm doesn't trip the inverter or send the Fault signal; SA and UV hold the output off while their cause lasts. Other error messages, warnings and faults in the same list that this page doesn't cover: HOLD, LOCD, Er1–Er4, Err., RB, PS, MT, SL, CF, LDF, EHR, DIP, IP, SE, LP, HP1–HP3, ED, E.SOT, E.LUP, E.LDN, E.OPT, E.16–E.20, E.PE2, E.USB, E.OS, E.OSD, E.ECT, E.OD, E.MB1–E.MB7, E.EP, E.OA, E.IAH, E.PID, E.CDO, E.CMB, E.1, E.10, E.11, E.13 – see the manual for those.

Sources: Mitsubishi Electric, FR-E800 Instruction Manual (Maintenance), IB(NA)-0600874ENG-P (December 2025) – chapter 2, Protective Functions (List of fault displays; Causes and corrective actions); Mitsubishi Electric, FR-E800 Instruction Manual (Function), IB(NA)-0600868ENG-U (May 2026) – monitor item selection (Pr.52) and the retry function (Pr.65, Pr.67, Pr.68), read on October 17, 2026.

Meanings, causes and checks are summarized in our own words. The manuals are the reference: they have every code, the full corrective actions and the safety instructions. A newer revision of a manual may add codes, so check the current revision for your drive.

FR-E800 inverters in stock

Mitsubishi FR-E800 (FR-E820, FR-E840) part numbers on our shelves right now. Every item is photographed, so check the nameplate – catalog number and series – against the drive you're replacing.

FR-E840-0026-5-60Mitsubishi FR-E840-0026-5-60 FREQROL E800 VFD Inverter Drive 3PH 380-480V 4.4A
FR-E840-0095-5-60Mitsubishi FR-E840-0095-5-60 Inverter 3PH AC380-480V480Y/277V 50/60Hz

Fault won't clear?

When the checks point to the drive itself – the manual's “replace the inverter” or “contact your sales representative” – send us the fault code and the catalog number from the nameplate. We check our shelves and our sourcing network and reply with a written quote. Purchase orders are welcome; payment is due before we ship.

Frequently asked questions

How do I reset a fault on a Mitsubishi FR-E800?

Fix the cause first and turn the start signal off – a reset with the start signal on restarts the motor suddenly. Then press STOP/RESET on the operation panel, turn on the RES signal for 0.1 s or more, or switch the power off and on. A reset also clears the electronic thermal count and the retry count.

What does E.OV3 mean on a Mitsubishi FR-E800?

E.OV3 is the regenerative overvoltage trip during deceleration or stop: energy coming back from the motor pushed the inverter's internal DC voltage too high. Lengthen the deceleration time, use the regeneration avoidance function, or add a brake resistor or brake unit for loads that keep regenerating.

What is the difference between OLC, OLV and E.OLT?

OLC and OLV are warnings: stall prevention is holding the frequency back because of high current (OLC) or high regenerated voltage (OLV), and the inverter keeps running. E.OLT is the fault that follows when stall prevention or the torque limit holds the motor at low speed for 3 seconds.

Are FR-E700 and FR-E800 fault codes the same?

Many codes carry the same names (E.OC1 to E.OC3, E.OV1 to E.OV3, E.THT, E.THM, E.FIN), but the FR-E800 adds codes such as E.UVT, E.PTC, E.EHR, E.PE6 and E.CMB and names its stall prevention warnings OLC and OLV. Use the manual for your series; we have a separate FR-E700 page.

Can you supply a replacement FR-E800 inverter?

Send the model from the rating plate (for example FR-E840-...) and the fault code through our quote form. We check our shelves and our sourcing network and reply with a written quote.

Mitsubishi FR-E800 fault codes: what they mean and what to check first

Quick answer

Reading and resetting an FR-E800 fault

Common FR-E800 fault codes

FR-E800 inverters in stock

Fault won't clear?

Frequently asked questions

Send us the fault code

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