Toshiba NC3 Fault Codes List

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Troubleshoot your Toshiba VF-NC3 compact drive with our updated fault code guide. Learn to use the “Easy” key, interpret OC and OL trips, and reset faults quickly.

Toshiba NC3 Fault Codes Reference Table

Below is the complete list of trip codes and alarms. Please refer to this table to match the flashing code on your inverter with the specific hardware issue.

Toshiba NC3 Fault Codes List

Toshiba NC3 Fault Codes List

Fault Code and Meaning Cause and Remedy
E (0011)
Emergency stop		 Cause:
During automatic operation or remote operation, an emergency stop command is entered from the operation panel or an external (terminal or communication).

Remedy:
  • Reset the inverter.
  • If the emergency stop signal is input, reset after releasing this signal.
E-13 (0045)
Over speed fault		 Cause:
The input voltage fluctuates abnormally.
Over speed fault due to the overvoltage limit operation.

Remedy:
  • Check the input voltage.
  • Install an optional braking module.
E-18 (0032)
Break in analog signal cable		 Cause:
The input signal from VI is equal to or less than the F633 setting.

Remedy:
  • Check the VI signal cable for breaks.
  • Check the input signal value or setting of F633.
E-19 (0033)
CPU communications error		 Cause:
A communications error occurs between control CPUs.

Remedy:
  • Contact your Toshiba distributor.
E-20 (0034)
Excessive torque boosted		 Cause:
The automatic torque boost parameter F402 setting is too high.
The motor has too small impedance.

Remedy:
  • Set a lower automatic torque boost parameter F402 setting.
  • Make an auto-tuning.
E-21 (0035)
CPU fault 2		 Cause:
The control CPU is defective.

Remedy:
  • Contact your Toshiba distributor.
E-26 (003A)
CPU fault 3		 Cause:
Internal CPU error.

Remedy:
  • Contact your Toshiba distributor.
EEP1 (0012)
EEPROM fault 1		 Cause:
The EEPROM is writing error.

Remedy:
  • Turn off the inverter, then turn it on again.
  • If it does not recover from the error, contact your Toshiba distributor.
EEP2 (0013)
EEPROM fault 2		 Cause:
TYP operation was aborted by power supply off etc.
The EEPROM is reading error.

Remedy:
  • Turn off the inverter, then turn it again, and then try TYP operation again.
  • If it does not recover from the error, contact your Toshiba distributor.
EEP3 (0014)
EEPROM fault 3		 Cause:
The EEPROM is defective.

Remedy:
  • Contact your Toshiba distributor.
EF2 (0022)
Ground fault trip		 Cause:
A ground fault occurs in the output cable or the motor.

Remedy:
  • Check the cable and the motor for ground faults.
EPH1 (0008)
Input phase failure		 Cause:
A phase failure occurred in the input line of the main circuit.
The capacitor in the main circuit lacks capacitance.

Remedy:
  • Check the main circuit input line for phase failure.
  • Set input phase failure detection selection F608=0.
  • Check the capacitor in the main circuit for exhaustion.
EPH0 (0009)
Output phase failure		 Cause:
A phase failure occurred in the output line of the main circuit.
The motor has too big impedance.

Remedy:
  • Check the main circuit output line, motor, etc. for phase failure.
  • Set output phase failure detection selection F605=0.
ERR2 (0015)
Main unit RAM fault		 Cause:
The control RAM is defective.

Remedy:
  • Contact your Toshiba distributor.
ERR3 (0016)
Main unit ROM fault		 Cause:
The control ROM is defective.

Remedy:
  • Contact your Toshiba distributor.
ERR4 (0017)
CPU fault 1		 Cause:
The control CPU is defective.

Remedy:
  • Contact your Toshiba distributor.
ERR5 (0018)
Remote control error		 Cause:
The communication with external devices was broken off.

Remedy:
  • Check the remote control device, cables, etc.
ETN (0028/0054/0055/0056)
Auto-tuning error		 Cause:
The motor parameters (uL, uLu, F405, F415, F417) are not set correctly.
The motor capacity is 2 classes or less than the inverter.
Output cable is too thin.
Motor is not connected.
Motor is rotating.

Remedy:
  • Set the parameters correctly as per motor nameplate and retry auto-tuning.
  • Set parameter F416 to smaller 70% of present value and retry.
  • If output cable is thin or special load, set F400=1 when trip occurs.
  • Connect the motor.
  • Check secondary magnetic contactor.
  • Wait for motor to stop rotating before auto-tuning.
ETYP (0029)
Inverter type error		 Cause:
It may be a breakdown failure.

Remedy:
  • Contact your Toshiba distributor.
OC1 (0001)
Overcurrent during acceleration		 Cause:
The acceleration time ACC is too short.
The V/F setting is improper.
A restart signal is input to the rotating motor after a momentary stop.
Special motor (small impedance) is used.
Cable length to motor is long.

Remedy:
  • Increase the acceleration time ACC.
  • Check the V/F parameter.
  • Use F301 (auto-restart) and F302 (ride-through control).
  • In case of Pt=0, 1, decrease vb.
  • In case of Pt=2, 3, 4, set F415 (Motor rated current) and make an auto-tuning.
  • Install AC reactors on the output side.
OC2 (0002)
Overcurrent during deceleration		 Cause:
The deceleration time dEC is too short.
The cable length to a motor is long.

Remedy:
  • Increase the deceleration time dEC.
  • Install AC reactors on the output side.
OC3 (0003)
Overcurrent during constant speed operation		 Cause:
The load fluctuates abruptly.
The load is in an abnormal condition.
The cable length to a motor is long.

Remedy:
  • Reduce the load fluctuation.
  • Check the load (operated machine).
  • Install AC reactors on the output side.
OCA (0005)
Arm overcurrent at start-up		 Cause:
A main circuit element is defective.

Remedy:
  • Contact your Toshiba distributor.
OCL (0004)
Overcurrent (load side at start-up)		 Cause:
The insulation of the output main circuit or motor is defective.
The motor has too small impedance.

Remedy:
  • Check the secondary wiring and insulation state.
  • Set F613=2, 3.
OH (0010)
Overheat		 Cause:
The cooling fan is life or fault.
The ambient temperature is high or low outside a specified ambient temperature.

Remedy:
  • The cooling fan requires replacement if it does not rotate. Contact distributor.
  • Operate at a specified ambient temperature.
OL1 (000D)
Inverter overload		 Cause:
Acceleration time ACC too short.
DC braking amount too large.
V/F setting improper.
Restart signal input to rotating motor.
Load is too large.

Remedy:
  • Increase acceleration time ACC.
  • Reduce DC braking amount F251 and time F252.
  • Check V/F parameter setting.
  • Use F301 (auto-restart) and F302 (ride-through).
  • Use an inverter with a larger rating.
  • Reduce F300 (PWM carrier frequency) to 4kHz or less.
OL2 (000E)
Motor overload		 Cause:
V/F setting improper.
Motor is locked up.
Low-speed operation performed continuously.
Excessive load applied.

Remedy:
  • Check V/F parameter setting.
  • Check the load (operated machine).
  • Adjust OLM to the overload the motor can withstand in low speed range.
OL3 (003E)
Main module overload		 Cause:
Carrier frequency is high and load current increased at low speeds (mainly 15Hz or less).

Remedy:
  • Raise the operation frequency.
  • Reduce the load.
  • Reduce F300 (PWM carrier frequency).
  • Set F316=1 (Carrier frequency with automatic reduction).
OP1 (000A)
Overvoltage during acceleration		 Cause:
Input voltage fluctuates abnormally (Power supply >200kVA, Capacitor open/close, Thyristor connected).
Restart signal input to rotating motor.

Remedy:
  • Insert a suitable input reactor.
  • Use F301 (auto-restart) and F302 (ride-through control).
OP2 (000B)
Overvoltage during deceleration		 Cause:
Deceleration time dEC is too short (Regenerative energy too large).
Overvoltage limit operation F305 is disabled.
Input voltage fluctuates abnormally.

Remedy:
  • Increase deceleration time dEC.
  • Set overvoltage limit operation F305 to 0, 2, 3.
  • Insert a suitable input reactor.
OP3 (000C)
Overvoltage during constant-speed		 Cause:
Input voltage fluctuates abnormally.
Motor is in regenerative state (load pushes motor faster than frequency).

Remedy:
  • Insert a suitable input reactor.
  • Install an optional brake module.
OT (0020)
Over-torque trip		 Cause:
Over-torque reaches detection level during operation.

Remedy:
  • Enable F615 (over-torque trip selection).
  • Check system error.
UC (001D)
Low-current operation Trip		 Cause:
Output current decreased to low-current detection level during operation.

Remedy:
  • Enable F610 (low-current detection).
  • Check suitable detection level (F609, F611, F612).
  • Contact distributor if setting is correct.
UP1 (001E)
Under voltage trip (main circuit)		 Cause:
The input voltage (in the main circuit) is too low.

Remedy:
  • Check the input voltage.
  • Enable F627 (undervoltage trip selection).
  • Set F627=0 or 2, F302 and F301 for momentary power failure measures.
A-05
Output frequency upper limit		 Cause:
Attempt made to operate at frequency higher than 10 times the base frequency.

Remedy:
  • Operate at a frequency within 10 times the base frequency.
A-17
Operation panel key alarm		 Cause:
RUN or STOP key held down for >20 seconds.
Key is faulty.

Remedy:
  • Check the operation panel.
ATN
Auto-tuning		 Cause:
Auto-tuning in process.

Remedy:
  • Normal if message disappears after a few seconds.
CLR
Clear command acceptable		 Cause:
Displayed when pressing STOP key while an error code is displayed.

Remedy:
  • Press the STOP key again to clear the trip.
DB
DC braking		 Cause:
DC braking in process.

Remedy:
  • Message goes off in several tens of seconds if no problem.
E1 / E2 / E3
Flowing out of excess number of digits		 Cause:
Number of digits (e.g. frequencies) is more than 4.

Remedy:
  • Lower the frequency free unit magnification F702.
E-49
External power supply logic switching check		 Cause:
Input terminal switched to sink logic of external power (+24V).

Remedy:
  • Remove connection of control terminals, reset or power cycle to switch logic.
E-50
Source logic switching check		 Cause:
Input terminal switched to source logic.

Remedy:
  • Informational alarm.
E-51
Sink logic switching check		 Cause:
Input terminal switched to sink logic.

Remedy:
  • Informational alarm.
EASY / STD
Switching display of Easy/Standard mode		 Cause:
EASY key was pushed.

Remedy:
  • Indicates mode change.
EOFF
Emergency stop command acceptable		 Cause:
Operation panel used to stop operation in auto/remote control mode.

Remedy:
  • Press STOP for emergency stop. Press any other key to cancel.
ERR1
Frequency point setting error		 Cause:
Frequency setting signals at points 1 and 2 are too close.

Remedy:
  • Set points 1 and 2 apart from each other.
HEAD / END
Display of first/last data items		 Cause:
First or last data item in group reached.

Remedy:
  • Press MODE key to exit data group.
HI / LO
Setting error alarm		 Cause:
Error found in a setting when data is reading or writing.

Remedy:
  • Check whether the setting is made correctly.
INIT
Parameters in initialization		 Cause:
Parameters are being initialized to default.

Remedy:
  • Normal if message disappears after a while.
LSTP
Auto-stop (continuous low limit)		 Cause:
Automatic stop function (F256) activated.

Remedy:
  • Function cancelled when freq reference reaches LL+0.2Hz or command OFF.
MOFF
Undervoltage in main circuit		 Cause:
Supply voltage between R, S, T is under voltage.
Shorting-bar between P0 and PA/+ removed (120V class).

Remedy:
  • Measure main circuit supply voltage.
  • Connect shorting-bar between P0 and PA/+.
NERR
No trip of past trip		 Cause:
No new record of past trip.

Remedy:
  • Normal operation.
OFF
ST terminal OFF		 Cause:
ST-CC circuit is opened.

Remedy:
  • Close the ST-CC circuit.
PASS / FAIL
Password verification		 Cause:
Result of password input for F739.

Remedy:
  • PASS = correct, FAIL = incorrect.
RTRY
Retry in process		 Cause:
Inverter in process of retry after momentary stop.

Remedy:
  • Inverter restarts automatically. Be careful.
SET
Input requirement of region setting		 Cause:
Power supplied to inverter for the first time.

Remedy:
  • Set region setting using setting dial (set SET to 0, TYP to 13).
STOP
Deceleration stop during power failure		 Cause:
Decel stop during power failure (F302) activated.

Remedy:
  • To restart, reset power or input operation signal again.
C
Overcurrent pre-alarm		 Cause:
Current flows at or higher than stall prevention level.

Remedy:
  • Same as OC (overcurrent).
H
Overheat pre-alarm		 Cause:
Overheat protection pre-alarm level reached.

Remedy:
  • Same as OH (overheat).
L
Overload pre-alarm		 Cause:
Cumulative overload reaches 50% or more of trip value.

Remedy:
  • Same as OL (overload).
P
Overvoltage pre-alarm		 Cause:
Voltage generated at or higher than stall prevention level.

Remedy:
  • Same as OP (overvoltage).
T
Communication pre-alarm		 Cause:
Communication broken off at or higher than F803 setting.

Remedy:
  • Same as ERR5 (communication fault).
 

How to Read NC3 Faults via the “Easy” Key & Dial

The VF-NC3 is designed for rapid diagnostics without external tools. In 2026, you can retrieve fault data using the intuitive front panel:

  • Current Fault: When a trip occurs, the display automatically flashes the fault code. Pressing the center Setting Dial allows you to toggle between the code and the output current/voltage at the time of the trip.
  • Trip History: The NC3 stores the last 4 trips. Press the MODE button until you reach the “Monitor” mode (displayed as nErr). Rotate the setting dial to scroll through past errors (Trip 1 through Trip 4).
  • Cumulative Run Time: By using the monitor menu, you can check the total power-on time to estimate the remaining life of the internal capacitors, a key feature for preventive maintenance.

General Troubleshooting Steps

Common issues with the NC3 often relate to setup or load mismatches. Perform these checks:

  1. Overcurrent (OC1/OC2/OC3): OC1 is during Accel, OC2 during Decel. Small drives like the NC3 trip easily if the acceleration time is too short for the load inertia. Increase parameter ACC or check for motor jams.
  2. Overload (OL1/OL2): OL1 is Motor Overload. Verify that the “Motor Rated Current” (Parameter tHr) matches the motor nameplate exactly. If set too low, the drive will trip prematurely.
  3. Overvoltage (OP1/OP2/OP3): This usually happens during deceleration. If the load is heavy (high inertia), the motor acts as a generator. Increase the Deceleration Time (Parameter dEC) or check the input voltage.

Frequently Asked Questions (FAQ)

Q: What does the flashing “C” code mean?

A: A flashing C (Current Limit) is a warning, not a trip. It indicates the motor is drawing high current, and the drive is automatically adjusting frequency to prevent an Overcurrent (OC) fault. If this happens frequently, your motor may be undersized for the application.

Q: How do I reset a Toshiba NC3 fault?

A: You can reset the drive using one of these methods:

  • Press the STOP/RESET key on the front panel twice.
  • Activate the digital input assigned to the RES function (usually via the terminal strip).
  • Cycle the main power (Turn OFF, wait for the screen to go dark, Turn ON).

Q: Can I connect the NC3 to a PC?

A: Yes. Unlike the NC1, the NC3 features an RS-485 port (RJ45 connector). You can connect it to a PC running PCM001Z software to view detailed trip logs and parameter settings, though the front dial is usually sufficient for basic troubleshooting.

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