INVT GD350-UL Series Drive Fault Codes List

Complete reference list of INVT GD350-UL (North American) fault codes. Learn to troubleshoot cULus listed drive errors, expansion card conflicts, and STO safety status.

INVT GD350-UL Fault Codes Reference Table

Use the search bar in the table below to quickly find your specific error code.

Goodrive350-UL Series VFD Troubleshooting

Fault Code and Meaning	Cause and Remedy
OUt1 VFD unit Phase-U protection	Cause: Acceleration is too fast; IGBT module is damaged; Misacts caused by interference; drive wires are poorly connected; To-ground short circuit. Remedy: Increase acceleration time. Replace the power unit. Check drive wires. Check whether there is strong interference surrounds the peripheral equipment.
OUt2 VFD unit Phase-V protection	Cause: Acceleration is too fast; IGBT module is damaged; Misacts caused by interference; drive wires are poorly connected; To-ground short circuit. Remedy: Increase acceleration time. Replace the power unit. Check drive wires. Check whether there is strong interference surrounds the peripheral equipment.
OUt3 VFD unit Phase-W protection	Cause: Acceleration is too fast; IGBT module is damaged; Misacts caused by interference; drive wires are poorly connected; To-ground short circuit. Remedy: Increase acceleration time. Replace the power unit. Check drive wires. Check whether there is strong interference surrounds the peripheral equipment.
OV1 Over-voltage during acceleration	Cause: Exception occurred to input voltage; Large energy feedback; Lack of brake units; Dynamic brake is not enabled. Remedy: Check input power. Check whether load deceleration time is too short. Check if the motor starts during rotating. Install dynamic brake units. Check the setting of related function codes.
OV2 Over-voltage during deceleration	Cause: Exception occurred to input voltage; Large energy feedback; Lack of brake units; Dynamic brake is not enabled. Remedy: Check input power. Check whether load deceleration time is too short. Check if the motor starts during rotating. Install dynamic brake units. Check the setting of related function codes.
OV3 Over-voltage during constant speed running	Cause: Exception occurred to input voltage; Large energy feedback; Lack of brake units; Dynamic brake is not enabled. Remedy: Check input power. Check whether load deceleration time is too short. Check if the motor starts during rotating. Install dynamic brake units. Check the setting of related function codes.
OC1 Over-current during acceleration	Cause: Acceleration is too fast; Grid voltage is too low; VFD power is too small; Load transient or exception occurred; To-ground short circuit or output phase loss occur; Strong external interference sources; Overvoltage stall protection is not enabled. Remedy: Increase acceleration/deceleration time. Check input power. Select the VFD with larger power. Check if the load is short circuited (to-ground or line-to-line) or if rotation is not smooth. Check the output wiring. Check if there is strong interference. Check the setting of related function codes.
OC2 Over-current during deceleration	Cause: See OC1 causes (Accel too fast, Grid low, VFD power small, Load transient, Short circuit, Interference). Remedy: Increase acceleration/deceleration time. Check input power. Select the VFD with larger power. Check if the load is short circuited (to-ground or line-to-line) or if rotation is not smooth. Check the output wiring. Check if there is strong interference. Check the setting of related function codes.
OC3 Over-current during constant speed running	Cause: See OC1 causes (Grid low, VFD power small, Load transient, Short circuit, Interference, Stall protection). Remedy: Check input power. Select the VFD with larger power. Check if the load is short circuited. Check the output wiring. Check if there is strong interference. Check the setting of related function codes.
UV Bus undervoltage fault	Cause: Grid voltage is too low; Overvoltage stall protection is not enabled. Remedy: Check grid input power. Check the setting of related function codes.
OL1 Motor overload	Cause: Grid voltage is too low; Rated motor current is set improperly; Motor stall or load jumps violently. Remedy: Check grid voltage. Reset rated motor current. Check the load and adjust torque boost.
OL2 VFD overload	Cause: Acceleration is too fast; The motor in rotating is restarted; Grid voltage is too low; Load is too large; Power is too small. Remedy: Increase acceleration time. Avoid restart after stop. Check grid voltage. Select the VFD with larger power. Select proper motor.
SPI Phase loss on input side	Cause: Phase loss or violent fluctuation occurred to R, S and T input. Remedy: Check the input power. Check installation wiring.
SPO Phase loss on output side	Cause: Phase loss occurred to U, V, W output (or the three phases of motor is asymmetrical). Remedy: Check the output wiring. Check the motor and cable.
OH1 Overheat of rectifier module	Cause: Air duct is blocked or fan is damaged; Ambient temperature is too high; Long-time overload running. Remedy: Ventilate the air duct or replace the fan. Lower the ambient temperature.
OH2 Overheat of VFD module	Cause: Air duct is blocked or fan is damaged; Ambient temperature is too high; Long-time overload running. Remedy: Ventilate the air duct or replace the fan. Lower the ambient temperature.
EF External fault	Cause: SI external fault input terminal acts. Remedy: Check external device input.
CE 485 communication fault	Cause: Baud rate is set improperly; Communication line fault; Communication address error; Communication suffers from strong interference. Remedy: Set proper baud rate. Check the wiring of communication interfaces. Set proper communication address. Replace or change the wiring to enhance anti-interference capacity.
ItE Current detection fault	Cause: Poor contact of the connector of control board; Hall component is damaged; Exception occurred to amplification circuit. Remedy: Check the connector and re-plug. Replace the hall component. Replace the main control board.
tE Motor autotuning fault	Cause: Motor capacity does not match with the VFD capacity (diff exceeds 5 power classes); Motor parameter is set improperly; The parameters gained from autotuning deviate sharply from standard; Autotuning timeout. Remedy: Change the VFD model, or adopt V/F mode for control. Set proper motor type and nameplate parameters. Empty the motor load and carry out autotuning again. Check motor wiring and parameter setting. Check whether upper limit frequency is larger than 2/3 of the rated frequency.
EEP EEPROM fault	Cause: R/W error occurred to the control parameters; EEPROM is damaged. Remedy: Press STOP/RST to reset. Replace the main control board.
PIDE PID feedback offline fault	Cause: PID feedback offline; PID feedback source disappears. Remedy: Check PID feedback signal wires. Check PID feedback source.
bCE Brake unit fault	Cause: Brake circuit fault or brake tube is damaged; The resistance of external brake resistor is too small. Remedy: Check the brake unit, replace with new brake tubes. Increase brake resistance.
END Running time is up	Cause: The actual running time of the VFD is larger than the set running time. Remedy: Ask help from the supplier, adjust the set running time.
OL3 Electronic overload fault	Cause: The VFD releases overload pre-alarm based on the set value. Remedy: Check the load and overload pre-alarm threshold.
PCE Keypad communication fault	Cause: The keypad wire is poorly contacted or disconnected; The keypad wire is too long and suffers strong interference; Circuit fault occurred to the keypad or communication part of the main board. Remedy: Check the keypad wires to confirm whether fault exists. Check the surroundings to rule out interference source. Replace the hardware and ask for maintenance service.
UPE Parameter upload error	Cause: The keypad wire is poorly contacted or disconnected; The keypad wire is too long and suffers strong interference; Circuit fault occurred to the keypad. Remedy: Check the surroundings to rule out interference source. Replace the hardware and ask for maintenance service.
DNE Parameter download error	Cause: The keypad wire is poorly contacted/disconnected; The keypad wire is too long/suffers interference; Data storage error occurred to the keypad. Remedy: Check the surroundings to rule out interference source. Replace the hardware and ask for maintenance service. Re-backup keypad data.
ETH1 To-ground short circuit fault 1	Cause: VFD output is short connected to the ground; Current detection circuit is faulty; Actual motor power setting deviates sharply from the VFD power. Remedy: Check whether motor wiring is proper. Replace the hall component. Replace the main control board. Reset the motor parameters properly.
ETH2 To-ground short circuit fault 2	Cause: VFD output is short connected to ground; Current detection circuit is faulty; Actual motor power setting deviates sharply from the VFD power. Remedy: Check whether motor wiring is proper. Replace the hall component. Replace the main control board. Reset the motor parameters properly.
dEu Speed deviation fault	Cause: Load is too heavy, or stall occurred. Remedy: Check the load to ensure it is proper, increase the detection time. Check whether control parameters are set properly.
STo Maladjustment fault	Cause: Control parameters of synchronous motor is set improperly; The parameter gained from autotuning is inaccurate; The VFD is not connected to motor. Remedy: Check the load to ensure it is proper. Check whether control parameters are set correctly. Increase maladjustment detection time.
LL Electronic underload fault	Cause: The VFD performs underload pre-alarm based on the set value. Remedy: Check the load and overload pre-alarm threshold.
ENC1O Encoder offline fault	Cause: Encoder line sequence is wrong, or signal wires are poorly connected. Remedy: Check the encoder wiring.
ENC1D Encoder reversal fault	Cause: The encoder speed signal is contrary to the motor running direction. Remedy: Reset encoder direction.
ENC1Z Encoder Z pulse offline fault	Cause: Z signal wires are disconnected. Remedy: Check the wiring of Z signal.
OT Motor over-temperature	Cause: Motor over-temperature input terminal is valid. Remedy: Check the wiring of motor over-temperature input terminal.
STO Safe torque off	Cause: Safe torque off function is enabled by external forces. Remedy: / (System state, not necessarily a failure).
STL1 Exception occurred to safe circuit of channel H1	Cause: The wiring of STO is improper. Fault occurred to external switch of STO. Hardware fault occurred to safety circuit of channel H1. Remedy: Check whether terminal wiring of STO is proper and firm enough. Check whether external switch of STO can work properly. Replace the control board.
STL2 Exception occurred to channel H2 safe circuit	Cause: The wiring of STO is improper. Fault occurred to external switch of STO. Hardware fault occurred to safety circuit of channel H2. Remedy: Check whether terminal wiring of STO is proper and firm enough. Check whether external switch of STO can work properly. Replace the control board.
STL3 Exception occurred to channel H1 and channel H2	Cause: Hardware fault occurred to STO circuit. Remedy: Replace the control board.
CrCE Safety code FLASH CRC check fault	Cause: Control board is faulty. Remedy: Replace the control board.
E-Err Repetitive extension card type	Cause: The two inserted extension cards are of the same type. Remedy: Users should not insert two cards with the same type. Check the type of extension card, and remove one card after power down.
ENCUV Encoder UVW loss fault	Cause: No electric level variation occurred to UVW signal. Remedy: Check the wiring of UVW. Encoder is damaged.
F1-Er Failed to identify the extension card in card slot 1	Cause: There is data transmission in interfaces of card slot 1, however, it cannot read the card type. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
F2-Er Failed to identify the extension card in card slot 2	Cause: There is data transmission in interfaces of card slot 2, however, it cannot read the card type. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
F3-Er Failed to identify the extension card in card slot 3	Cause: There is data transmission in interfaces of card slot 3, however, it cannot read the card type. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
C1-Er Communication timeout occurred to the extension card in card slot 1	Cause: There is no data transmission in interfaces of card slot 1. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
C2-Er Communication timeout occurred to the extension card in card slot 2	Cause: There is no data transmission in interfaces of card slot 2. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
C3-Er Communication timeout occurred to the extension card in card slot 3	Cause: There is no data transmission in interfaces of card slot 3. Remedy: Confirm whether the extension card inserted can be supported. Stabilize the extension card interfaces after power down, and confirm whether fault still occurs at next power-on. Check whether the insertion port is damaged, if yes, replace the insertion port after power down.
E-DP Profibus card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
E-NET Ethernet card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer. Remedy: Check whether the communication card wiring is loose or dropped.
E-CAN CANopen card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
E-PN PROFINET card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
E-CAT EtherCAT card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
E-BAC BACNet card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
E-DEV DeviceNET card communication timeout fault	Cause: There is no data transmission between the communication card and the host computer (or PLC). Remedy: Check whether the communication card wiring is loose or dropped.
ESCAN Can master/slave communication card communication timeout fault	Cause: There is no data transmission between the CAN master and slave communication cards. Remedy: Check whether the communication card wiring is loose or dropped.
S-Err Master-slave synchronous CAN slave fault	Cause: Fault occurred to one of the CAN slave VFDs. Remedy: Detect the CAN slave VFD and analyze the corresponding fault cause of the VFD.
PoFF System power failure	Cause: The system is powered off or the bus voltage is too low. Remedy: Check the grid conditions.

 

Advanced Diagnostics: Bluetooth & Expansion Slots

The GD350-UL distinguishes itself with advanced connectivity options that simplify troubleshooting in the field.

• Bluetooth & Wi-Fi Diagnostics: The GD350-UL supports a wireless keypad option. Using the INVT Workshop App on your smartphone, you can download fault logs, view real-time oscilloscope traces, and export parameters without opening the electrical cabinet (reducing arc flash exposure).
• Slot-Specific Faults: The drive features three expansion slots (Slot 1, 2, and 3). Errors often point to a specific card configuration:
  • Slot 1: Typically used for PLC or I/O cards.
  • Slot 2: Typically used for Encoder (PG) cards.
  • Slot 3: Typically used for Fieldbus (EtherNet/IP, Modbus TCP, Profinet).
• Safe Torque Off (STO): The GD350-UL includes built-in SIL 3 STO. Unlike older drives that just cut power, this status is monitored logically. If the display shows “STO”, the safety circuit is open.

Frequently Asked Questions (FAQ)

Q: The drive shows “STO” and will not start. Is it faulty?

A: No. STO stands for Safe Torque Off. In North American installations, this replaces the main contactor for emergency stops.
Action: Check the safety inputs at terminals H1 and H2. If you are benchmarking the drive on a desk without a safety relay, you must install the factory-supplied jumpers between +24V and H1/H2.

Q: I am getting an “ETH” (Ground Fault) on a 480V Delta system. Why?

A: ETH indicates a ground fault. On ungrounded (Delta) or High-Resistance Ground (HRG) power systems common in older US facilities, voltage imbalances can trigger false trips.
Fix:
1. Verify the motor insulation with a megohmmeter (Megger).
2. If the motor is fine, you may need to remove the EMC/RFI Screws (Varistors/Capacitors) on the side of the drive to disconnect the internal filter from ground.

Q: What does “PrE” (Parameter Read/Write Error) mean?

A: This often happens when copying parameters via the keypad or keypad-copy function.
Cause: The firmware version of the keypad does not match the drive, or the source drive had an expansion card that the target drive lacks. Ensure both drives have identical hardware configurations before cloning.