VFD Fault Codes — What They Mean and How to Clear Them

Quick Answer

VFD fault codes are the drive's diagnostic output — each code points to a specific subsystem failure: motor overcurrent, insulation ground fault, DC bus overvoltage, heatsink overtemperature, or fieldbus communication loss. The fault code alone narrows the root cause to one of these five categories. The fault history log (available on every industrial VFD) adds the operating data at the time of trip — current, voltage, frequency, temperature — which isolates the specific failure mechanism within that category. This guide covers the fault code systems for the five most common industrial VFD platforms and the correct procedure for reading, recording, and clearing faults without losing diagnostic data.

Why You Must Read the Fault Code Before Resetting

The single most important rule in VFD fault code diagnosis: never reset the drive until you have recorded the active fault code and reviewed the fault history log. The complete VFD troubleshooting guide details a real-world case where repeated blind resets escalated a $200 bearing problem into a $4,500 drive replacement. Every VFD stores between 5 and 20 historical fault records with operating snapshots. On many platforms, pressing the reset button or cycling input power clears this history permanently.

Before touching the reset button, record:

1. Active fault code — displayed on the drive keypad or HMI. Photograph it.
2. Fault history log — navigate to the drive's fault log parameter group. Record all stored faults, timestamps, and operating data (current, DC bus voltage, output frequency, heatsink temperature).
3. Drive status indicators — LED patterns on the drive front panel often provide additional diagnostic information beyond the fault code.
4. Operating context — what was the motor doing when it faulted? Starting, running at full speed, decelerating, or idle? The operating state at fault time is critical for root cause identification.

How to Read Fault Codes on Allen-Bradley PowerFlex 525/755

Allen-Bradley PowerFlex drives use an F-code system displayed on the integral HIM (Human Interface Module) or through Connected Components Workbench (CCW) software. The fault queue stores the last 8 faults with full operating data.

Top PowerFlex Fault Codes

• F002 — Auxiliary Input — External fault signal received on a digital input configured as a fault input. Check the external device (overload relay, pressure switch, level switch) wired to the configured digital input.
• F005 — Power Loss — DC bus voltage dropped below the minimum threshold during operation. Caused by a momentary power dip, loose input connections, or undersized input conductor. Check input terminal torque and incoming voltage stability with a power quality meter.
• F007 — Motor Overcurrent — Output current exceeded the instantaneous current limit (typically 200% of drive rated current). At low speed: suspect mechanical jam, seized bearing, or motor winding short. At full speed: suspect motor FLA parameter mismatch or increasing mechanical load.
• F033 — Auto Restart Tries — The drive attempted the configured number of automatic restarts and failed. Indicates a persistent fault condition that auto-restart cannot clear. Investigate the underlying fault that triggered the restart attempts.
• F041 — Ground Fault — Current imbalance between output phases exceeds the GF threshold (parameter A092). Disconnect motor leads at the drive output and megohmmeter test each phase to ground per IEEE Std 43-2013. Readings below 1 MΩ per kV indicate insulation failure.
• F064 — Motor Overtemperature — Motor thermal model calculated winding temperature above the trip threshold, or a PTC/PT100 motor thermistor input exceeded its setpoint. Check actual motor surface temperature, verify motor service factor, and confirm the drive's motor thermal model parameters match the motor nameplate data.

Accessing the PowerFlex Fault Queue

Navigate to parameter group F (Faults): F700–F707 stores the last 8 faults. Each fault record includes F720–F727 (output current at fault), F740–F747 (DC bus voltage at fault), and F760–F767 (output frequency at fault). In CCW, the Fault Log viewer presents this data graphically with export capability. Always export the fault log before clearing.

How to Read Fault Codes on ABB ACS580

ABB ACS580 drives use a 4-digit fault numbering system displayed on the assistant control panel. The fault logger stores the last 20 faults with a comprehensive operating snapshot — the most detailed fault logging of any standard industrial VFD.

Top ABB ACS580 Fault Codes

• 2310 — Overcurrent — Output current exceeded the hardware current limit. Resolution: check motor and cable insulation with megohmmeter, verify motor nameplate data matches drive parameters (parameter group 99), and increase acceleration time if fault occurs during ramp-up.
• 3210 — Overvoltage — DC bus voltage exceeded 410 VDC (230V unit) or 820 VDC (480V unit). Resolution: increase deceleration time, enable overvoltage controller (parameter 22.03), or install a dynamic braking resistor for high-inertia loads.
• 3220 — Undervoltage — DC bus voltage dropped below the minimum operating threshold. Check incoming supply voltage, input fuses, and contactor coil for intermittent dropout.
• 5100 — AI Supervision — An analog input signal is below the configured wire-break detection threshold (typically 3.5 mA for a 4–20 mA signal). Check the transmitter, signal wiring, and AI terminal connections.
• 7121 — Motor Overtemperature — Motor thermal model trip or PTC thermistor input. Verify motor cooling (fan, shroud, ambient), check for overload condition, and confirm motor thermal model parameters.
• A200 — Ground Fault — Current imbalance detected on output phases. ABB ACS580 trips at approximately 50% of rated current imbalance. Perform the VFD ground fault isolation procedure — disconnect motor leads and megohmmeter test cable and motor separately.

Accessing the ACS580 Fault Logger

Press Menu → Diagnostics → Fault logger. Each entry shows the fault code, timestamp, output current, DC bus voltage, output frequency, motor speed, motor torque, and heatsink temperature. Use ABB Drive Composer (free software) for full fault log export over USB or Ethernet. Back up the full parameter set (parameter group 96, Backup/Restore) before making any parameter changes during troubleshooting.

How to Read Fault Codes on Yaskawa GA800

Yaskawa GA800 drives use letter-based fault codes displayed on the keypad or readable through DriveWizard Mobile (Bluetooth connection). The fault trace stores the last 16 faults with operating data.

Top Yaskawa GA800 Fault Codes

• oC — Overcurrent — Output current exceeded the instantaneous trip level. Yaskawa subdivides this into oC1 (during acceleration), oC2 (during deceleration), and oC3 (at constant speed) — each narrows the root cause. oC1 points to mechanical load or motor problems during startup. oC3 suggests a winding short or increasing process load.
• ov — Overvoltage — DC bus exceeded trip threshold. Increase deceleration time (C1-02) or enable the Yaskawa's built-in Stall Prevention function (L3-04) which automatically extends deceleration to prevent OV trips.
• GF — Ground Fault — Output current imbalance between phases. Megohmmeter test motor and cable separately to locate the insulation failure.
• oH — Overtemperature (heatsink) — Check cooling fan operation, clean heatsink fins, and verify enclosure ventilation. Yaskawa GA800 displays real-time heatsink temperature in parameter U1-03.
• oH1 — Motor Overtemperature — Motor thermal model or PTC input trip. Verify motor parameters match nameplate (E1-01 through E1-06).
• CPF00 — EEPROM Error — Drive memory corruption. Initialize drive parameters to factory defaults (A1-03 = 1110) and re-enter motor and application parameters.

Using DriveWizard Mobile for Fault Diagnosis

Yaskawa's DriveWizard Mobile app connects to the GA800 over Bluetooth (no cable required) and provides a graphical fault trace viewer with parameter comparison and trending. The app also accesses the Maintenance Monitor — which tracks DC bus capacitor life percentage, cooling fan run hours, IGBT thermal cycle count, and inrush relay operation count. These predictive metrics flag components approaching end of life before they cause a fault.

How to Read Fault Codes on Danfoss FC-302

Danfoss FC-302 drives use numeric alarm codes displayed on the LCP (Local Control Panel) and readable through VLT Motion Control Tool MCT 10 or the MyDrive Insight cloud platform.

Top Danfoss FC-302 Alarm Codes

• Alarm 2 — Live Zero Error — Analog reference input signal below the configured minimum (default 2 mA for a 4–20 mA input). Check transmitter output, wiring, and terminal connections.
• Alarm 7 — DC Overvoltage — DC bus exceeded trip threshold. Increase deceleration time (parameter 3-81) or enable the Extended Braking (parameter 2-17) function that applies a controlled overvoltage limit.
• Alarm 12 — Current Limit — The drive has been current-limiting for the duration set in parameter 14-24. Motor current reached the configured current limit and could not recover. Check mechanical load and verify motor parameters.
• Alarm 13 — Overcurrent — Instantaneous output current limit exceeded (~200% of rated current). Investigate motor, cable, and mechanical load.
• Alarm 14 — Earth (Ground) Fault — Current leakage to ground detected. Disconnect motor at drive output terminals and test insulation per IEEE Std 43-2013.
• Alarm 29 — Heatsink Overtemperature — Check cooling fan, ambient temperature, and enclosure ventilation.

Danfoss Alarm Word and Warning Word

The FC-302 provides two 16-bit registers (parameter 16-01 Alarm Word and parameter 16-05 Warning Word) that encode all active alarms and warnings as individual bits. These registers are readable over Modbus RTU/TCP and are critical for PLC-to-SCADA integration — the PLC can read the alarm word in a single register read and decode all active fault conditions without polling individual parameters.

How to Read Fault Codes on Siemens SINAMICS G120

Siemens SINAMICS G120 drives use an F3xxxx fault numbering system displayed on the BOP (Basic Operator Panel) or IOP (Intelligent Operator Panel). Faults are also viewable in STARTER or SINAMICS Startdrive commissioning software.

Top Siemens SINAMICS G120 Fault Codes

• F30001 — Motor Overcurrent — Instantaneous output current limit exceeded. Check motor and cable insulation, verify motor data in parameter set p0300–p0311, and increase acceleration ramp (p1120).
• F30002 — DC Bus Overvoltage — DC bus exceeded the maximum threshold. Increase deceleration time (p1121) or enable Vdc-controller (p1240). Install a braking resistor for high-inertia loads.
• F30003 — DC Bus Undervoltage — Input power dip or loss. Check supply voltage, input fuses, and mains contactor.
• F30004 — Drive Overtemperature — Heatsink temperature exceeded limit. Check internal fan, ambient temperature, and enclosure ventilation. Use parameter r0037 to read current heatsink temperature.
• F30021 — Ground Fault — Output current imbalance detected. Disconnect motor and megohmmeter test motor windings and cable separately. Pay attention to the Siemens fault value — it indicates which phase is faulted.
• F30024 — Motor Overtemperature — Motor I²t thermal model trip or KTY/PTC sensor input. Verify motor cooling and motor data parameters.

SINAMICS Fault Buffer

The SINAMICS G120 stores the last 8 faults in the fault buffer, accessible via parameters r0945 (fault code), r0947 (fault time), and r0949 (fault value). The fault value is particularly useful — for overcurrent faults it shows the current magnitude, for overvoltage it shows the DC bus voltage, and for overtemperature it shows the heatsink temperature at the time of trip. Siemens Startdrive provides a graphical Diagnostics view that displays the fault buffer with full context and recommended actions.

The Correct Fault Clearing Procedure

After recording all fault data, clear the fault using the method appropriate to your drive platform and application:

1. Verify the root cause is addressed — Do not clear a fault if the underlying problem has not been identified or fixed. Clearing and re-running into the same fault condition risks equipment damage.
2. Clear via keypad — Most drives clear faults by pressing the STOP/RESET button on the keypad or navigating to a reset parameter. This preserves the fault history log on most platforms.
3. Clear via digital input — If the drive is configured for remote fault reset via a PLC digital output, verify the PLC logic includes a one-shot (not a maintained contact) to prevent continuous reset cycling. The VFD-to-PLC integration guide covers fault reset interlock logic.
4. Power cycle (last resort) — Cycling input power clears the active fault but may also clear the fault history log on some platforms. Use this only when keypad or digital input reset is unavailable or when the fault prevents keypad operation.
5. Verify after clearing — After clearing the fault, run the drive at low speed (10–15 Hz) and monitor output current for 5–10 minutes before ramping to full speed. If the fault recurs immediately, stop and continue diagnosis.

When Fault Codes Alone Are Not Enough

Certain failure modes produce misleading or generic fault codes that require additional testing beyond what the fault code indicates. Intermittent overcurrent faults with no pattern may indicate incipient motor winding failure that passes a static megohmmeter test but fails under operating temperature and voltage stress. In these cases, a systematic troubleshooting approach using motor circuit analysis (MCA) or surge testing provides deeper insight into winding condition than standard megohmmeter testing alone. NFM Consulting's SCADA and industrial controls engineering team provides VFD commissioning, fault diagnosis, and drive replacement services across all five major VFD platforms at Texas industrial and oilfield facilities.