Toshiba S15 Fault Codes List

Troubleshoot your Toshiba VF-S15 drive with our updated fault code guide. Learn to interpret OC, OL, and OP trips, use the Easy Key diagnostics, and reset faults.

Toshiba S15 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 or parameter issue.

Toshiba VF-S15 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 / 002D Over speed fault	Cause: The input voltage fluctuates abnormally; Over speed fault due to the overvoltage limit operation; When Pt=6, the inverter started without connecting the PM motor. Remedy: Check the input voltage. Install an optional dynamic braking resistor (optional). Connect the PM motor or change Pt setting.
E-18 / 0032 Analog input break detection fault	Cause: The input signal from VIC is equal to or less than the F633 setting. Remedy: Check the VIC 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 Over torque boost fault	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-23 / 0037 Optional unit fault 2	Cause: An optional device is defective. Remedy: Contact your Toshiba distributor.
E-26 / 003A CPU fault 3	Cause: The control CPU detected a fault. Remedy: Reset the inverter. The cause can be surrounding noise. If the problem is not solved, contact your Toshiba distributor.
E-31 / 003F Heavy cycle of main power ON/OFF	Cause: Main power ON/OFF during running is repeated frequently; Initial failure if it is caused by other reasons. Remedy: Reduce the frequency of repetition of main power ON/OFF during running. Contact your Toshiba distributor.
E-32 / 0040 PTC fault	Cause: PTC thermal protection is occurred. Remedy: Check the PTC in motor.
E-37 / 0045 Servo lock fault	Cause: The motor shaft is not locked in servo lock operation. Remedy: Reduce the load in servo lock operation.
E-39 / 0047 Auto-tuning error (PM motor)	Cause: When auto-tuning (relating parameters are Pt=6, F400=2), the current of the permanent magnet motor exceeded the threshold level; The inductance of permanent magnet motor is too small; The motor is not connected. Remedy: Auto tuning for permanent magnet motor is not allowed for this motor, please measure inductance with the LCR meter etc. Set V/F control mode selection Pt = 0, for operation check without connecting motor.
EEP1 / 0012 EEPROM fault 1	Cause: The EEPROM writing error occurs. Remedy: Turn off the inverter, then, turn it again. If it does not recover from the error, contact your Toshiba distributor.
EEP2 / 0013 EEPROM fault 2	Cause: typ operation is aborted by the power-off etc; The EEPROM reading error occurs. Remedy: Turn off the inverter, then, turn it again, and then try typ operation again. Turn off the inverter, then, turn it 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	Cause: A ground fault occurs in the output cable or the motor; A ground fault occurs in dynamic braking resistor; When inverters are fed by AC power supply and connected with common DC bus link, unnecessary trip occurs. Remedy: Check the cable and the motor for ground faults. Set the parameter F614 to 0 “Disabled”.
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. 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. Select output phase failure detection parameter F605. When Pt = 6 and F915 = 3 to 4, output phase failure detection is valid regardless of F605 setting.
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 Communication error	Cause: The communication with external devices is broken off. Remedy: Check the remote control device, cables, etc.
ERR7 / 001A Current detector fault	Cause: The current detector is defective. Remedy: Contact your Toshiba distributor.
ERR8 / 001B Optional unit fault 1	Cause: An optional unit has failed (such as a communication option). Remedy: Check the connection of optional unit.
ERR9 / 001C Remote keypad disconnection fault	Cause: After run signal is activated by RUN key of the remote keypad, disconnection is occurred in 10 seconds or more. Remedy: In case the remote keypad is disconnected, press STOP key before. This fault is disabled by F731=1 setting.
ETN / 0028 ETN1 / 0054 ETN2 / 0055 ETN3 / 0056 Auto-tuning error	Cause: The motor parameter uL, uLu, F405, F415, F417 are not set correctly; The motor with the capacity of 2 classes or less than the inverter is used; The output cable is too thin; The motor is not connected; Power supply of main circuit does not turn on; The motor is rotating; Parameter Pt=6 is set and High speed motor is connected. Remedy: Set the left column parameters correctly as a motor name plate and make an auto-tuning again. Set parameter F416 to smaller 70% of the present value, and execute the auto-tuning again. Set F400=1 when trip occurs. Connect the motor. Check whether the secondary magnetic contactor is on. Turn on power supply of main circuit. Make an auto-tuning again after the rotation of the motor stops. Choose the higher power range drive.
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; A special motor (small impedance) is used; Low inductance motor (High speed motor); Connecting cable length is long. Remedy: Increase the acceleration time ACC. Check the V/F parameter setting. Use F301 (auto-restart) and F302 (ride-through control). In case of Pt=0, 1, 7, decrease ub. In case of Pt=2 to 6, set F415 and make an auto-tuning. Choose the higher power range drive. AC reactors etc. are required for the output side.
OC2 / 0002 Overcurrent during deceleration	Cause: The deceleration time dEC is too short; Low inductance motor (High speed motor) is used; The connecting cable length is long. Remedy: Increase the deceleration time dEC. Choose the higher power range drive. AC reactors etc. are required for the output side.
OC3 / 0003 Overcurrent during constant speed operation	Cause: The load fluctuates abruptly; The load is in an abnormal condition; Low inductance motor (High speed motor) is used; The connecting cable length is long. Remedy: Reduce the load fluctuation. Check the load (operated machine). Choose the higher power range drive. AC reactors etc. are required for the output side.
OCA / 0005 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 reaches the end of life or has a fault; The ambient temperature is too high; The vent is blocked up; A heat generating device is installed close to the inverter; The load is large; The temperature sensor has a fault. Remedy: The fan requires replacement if it does not rotate. Operate at a specified ambient temperature. Secure sufficient space around the inverter. Reduce the load or reduce F300 (PWM carrier frequency). Contact your Toshiba distributor if sensor is faulty.
OH2 / 002E Thermal fault stop command from external device	Cause: A thermal trip command (input terminal function: 46 or 47) is issued by an external control device. Remedy: The motor is overheated, so check whether the current flowing into the motor exceeds the rated current.
OL1 / 000D Inverter overload	Cause: The acceleration time ACC is too short; The DC braking amount is too large; The V/F setting is improper; A restart signal is input to the rotating motor; The load is too large. Remedy: Increase the acceleration time ACC. Reduce the DC braking amount F251 and time F252. Check the V/F parameter setting. Use F301 (auto-restart) and F302 (ride-through control). Use an inverter with a larger rating or reduce F300 (PWM carrier frequency).
OL2 / 000E Motor overload	Cause: The V/F setting is improper; The motor is locked up; Low-speed operation is performed continuously; An excessive load is applied to the motor. Remedy: Check the V/F parameter setting. Check the load (operated machine). Adjust OLM to the overload that the motor can withstand during operation in a low speed range.
OL3 / 003E Main module overload	Cause: The carrier frequency is high and load current has increased at low speeds (mainly at 15Hz or less). Remedy: Raise the operation frequency. Reduce the load. Reduce F300 (PWM carrier frequency). Set carrier frequency control mode selection F316 to 1, 3 or 5.
OLR / 000F Dynamic braking resistor overload trip	Cause: The deceleration time is too short; Dynamic braking is too large. Remedy: Increase the deceleration time dEC. Increase the capacity of dynamic braking resistor (wattage) and adjust PBR capacity parameter F309.
OP1 / 000A Overvoltage during acceleration	Cause: The input voltage fluctuates abnormally; A restart signal is input to the rotating motor after a momentary stop. Remedy: Insert a suitable input reactor. Use F301 (auto-restart) and F302 (ride-through control).
OP2 / 000B Overvoltage during deceleration	Cause: The deceleration time dEC is too short (Regenerative energy is too large); Overvoltage limit operation F305 is set to 1 (Disabled); Input voltage fluctuates abnormally. Remedy: Increase the deceleration time dEC. Set overvoltage limit operation F305 to 0, 2, 3. Insert a suitable input reactor.
OP3 / 000C Overvoltage during constant speed operation	Cause: The input voltage fluctuates abnormally; The motor is in a regenerative state because the load causes the motor to run at a frequency higher than the inverter output frequency. Remedy: Insert a suitable input reactor. Install an optional dynamic braking resistor (optional).
OT / 0020 Over-torque trip 1	Cause: Over-torque reaches to a detection level during operation. Remedy: Enable F615 (over-torque trip selection). Check system error.
OT2 / 0041 Over-torque trip 2	Cause: Output current reached F601 or more and maintain in F452 during power running. Remedy: Reduce the load. Increase the stall prevention level or power running torque limit level.
OTC3 / 0048 Over-torque / Overcurrent fault	Cause: Power running torque or output current reached F593 or more and maintain in F595 during power running. Remedy: Enable F591. Reduce the load. Check system error.
PRF / 003B Safe torque off error	Cause: Error of safe torque off circuit. Remedy: Contact your Toshiba distributor.
SOUT / 002F Step-out (for PM motor drive only)	Cause: The motor shaft is locked; One output phase is open; An impact load is applied; Using the DC braking function. Remedy: Unlock the motor shaft. Check the interconnect cables between the inverter and the motor. Prolong the acceleration / deceleration time. Turn off the Step-out function when using the DC braking function or change the DC braking to Servo lock function.
UC / 001D Low-current operation fault	Cause: The output current decreased to a low-current detection level during operation. Remedy: Enable F610 (low-current detection). Check the suitable detection level for the system (F609, F611, F612).
UP1 / 001E Undervoltage fault (main circuit)	Cause: The input voltage (in the main circuit) is too low. Remedy: Check the input voltage. Enable F627 (undervoltage trip selection). To take measures to momentary power failure, set F627=0, Regenerative power ride-through control F302 and Auto-restart control selection F301.
UTC3 / 0049 Small-torque / Small-current fault	Cause: Power running torque or output current decreased F593 or less and maintain in F595 during power running. Remedy: Enable F591. Check system error.
A-01 Points setting alarm 1	Cause: In case of Pt=7, there are same setting value at least two on parameter uL, F190, F192, F194, F196, or F198 except 0.0Hz. Remedy: Set the points to different values.
A-02 Points setting alarm 2	Cause: In case of Pt=7, the inclination of V/f is too high. Remedy: Set the inclination of V/f to be flat.
A-05 Output frequency upper limit	Cause: An attempt was made to operate at a frequency higher than 10 times the base frequency (uL or F170). Remedy: Operate at a frequency within 10 times the base frequency.
A-17 Operation panel key alarm	Cause: The RUN or STOP key is held down for more than 20 seconds; The RUN or STOP key is faulty. Remedy: Check the operation panel.
A-18 Break in analog signal cable	Cause: The signal input via VIC is below the analog signal detection level set with F633. Remedy: Check the cables for breaks. And check the setting of input signal or setting value of F633.
A-28 S3 terminal alarm	Cause: Slide switch SW2 and parameter F147 settings are different. Remedy: Match the settings of SW2 and F147. Power supply OFF and ON after these settings.
EOFF Emergency stop command acceptable	Cause: The operation panel is used to stop the operation in automatic control or remote control mode. Remedy: Press the STOP key for an emergency stop. To cancel the emergency stop, press any other key.
MOFF Undervoltage in main circuit	Cause: The supply voltage between R, S and T is under voltage; Internal communication fault. Remedy: Measure the main circuit supply voltage. If the voltage is at a normal level, the inverter requires repairing for fault.
PRA STO signal OFF	Cause: STO terminal is in open-circuit; Input voltage of STO terminal is low; The voltage of P24 terminal decreases. Remedy: Close STO and + SU circuit. Check the load of P24 terminal. Check the polarity of the surge absorption diode.
RTRY Retry in process	Cause: The inverter is in process of retry. A momentary stop occurred. Remedy: The inverter restarts automatically. Be careful of the machine because it may suddenly restart.
TUN / TUN1 / TUN2 / TUN3 Learning / Tuning errors	Cause: Errors in brake sequence learning or light-load high-speed learning operations; Load too heavy; Motor constants not entered correctly. Remedy: To cancel learning, suspend it and set learning parameters F329 to 0. Check whether the learning operation is performed correctly. Check the load and motor constant settings.
C / P / L / H Pre-alarms	Cause: Overcurrent, Overvoltage, Overload, or Overheat pre-alarm levels have been reached. Remedy: Refer to remedies for OC (Overcurrent), OP (Overvoltage), OL (Overload), or OH (Overheat).

 

How to Read S15 Faults via Easy Key & Dial

The S15 features a dedicated EASY key and a large setting dial, making it one of the most user-friendly drives to troubleshoot in 2026:

• Current Fault: When the drive trips, the display flashes the fault code. Pressing the center of the setting dial allows you to toggle between the code and the output current/voltage at the moment of the trip.
• Trip History: The S15 stores the last 4 trips. Press the MODE button to enter “Monitor” mode (display shows nErr). Rotate the dial to view Past Trip 1 through 4.
• PC Connection: Unlike older models, the S15 has a standard front-facing port (often Mini-USB or RJ45 depending on the specific sub-model) to connect to the PCM001Z software for downloading parameter files and detailed crash logs.

General Troubleshooting Steps

Most S15 faults are related to load setup or power supply issues. Perform these checks:

1. Overcurrent (OC1/OC2/OC3): Short circuit or locked rotor. If the fault occurs during startup (OC1), check the “Torque Boost” parameter. If it is set too high for the motor, it can cause saturation and an immediate trip.
2. Overload (OL1/OL2): OL1 is Motor Overload. Verify that the “Motor Rated Current” (Parameter tHr) matches the motor nameplate. If you are using a PM motor, ensure the drive is in “PM Control Mode” and not V/f mode.
3. Overvoltage (OP1/OP2/OP3): High DC bus voltage. This usually happens during rapid deceleration. Increase the Deceleration Time (Parameter dEC) or check if the braking resistor is connected and the “Braking Resistor Selection” parameter is enabled.

Frequently Asked Questions (FAQ)

Q: What does the “Init” code mean?

A: Init is not a fault; it indicates the drive is initializing. If this stays on the screen, it may indicate a CPU error or that the 24V control power is too low to fully boot the system.

Q: How do I reset a Toshiba S15 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 (Terminal S3 is default for Reset in many macros).
• Cycle the main power (Turn OFF, wait for the screen to go dark, Turn ON).

Q: Why is the “Easy” key light flashing?

A: If the “Easy” key LED is flashing, it means the drive is in “Easy Mode,” which filters the parameter list to show only the most commonly used settings. Pressing it again returns you to “Standard Mode” (all parameters).