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Reading & Clearing Common VFD Fault Codes
Drives · Troubleshooting
Reading & Clearing
Common VFD Fault Codes
A fault code on a VFD tells you which protection tripped, not necessarily what went wrong. Here's how to look up a code for your brand, understand the common fault categories and their usual causes, and decide whether to clear the fault or replace the drive.
01 / Overview What a Fault Code Tells You
A trip is a symptom, not a diagnosis
A VFD monitors its own current, voltage, temperature, and signals, and when something moves outside safe limits it stops and displays a fault. That makes VFD fault codes a useful starting point, but a code usually names the protection that tripped rather than the root cause. An overcurrent fault, for example, can come from the drive, the motor, the cable, or the load.
This guide covers the practical side of drive error troubleshooting: the common fault categories, how to find the exact meaning of a code for your brand, what to check first, and how to tell when a drive needs replacing rather than resetting.
02 / Categories Common Fault Categories
Most codes fall into a handful of groups
Code names and numbers differ from one manufacturer to the next, but the underlying protections are broadly the same. Knowing the category gets you thinking in the right direction even before you find the exact code.
01
Overcurrent
Output current exceeded a limit, during acceleration, at steady speed, or on a sudden load change.
02
Overvoltage
The DC bus voltage rose too high, often during fast deceleration or from a high supply.
03
Undervoltage
The DC bus or supply dropped too low, from a sagging supply or momentary power loss.
04
Overtemperature
The drive's heatsink or internal temperature went past its limit.
05
Ground Fault / Short
Current was detected flowing where it shouldn't, to ground or between output phases.
06
Motor Overload
The motor drew more current than its rating allows for too long.
07
Phase Loss
An input or output phase is missing or unbalanced.
08
Control & Comms
A lost signal, a feedback problem, or a network communication timeout.
03 / Lookup Looking Up a Code by Brand
Always confirm the exact code in the drive's manual
The same abbreviation can mean different things on different drives, and even within one brand, meanings can change between models. Treat the category list above as orientation, and confirm the specific meaning in the documentation for your exact drive.
| Step | What to Do |
|---|---|
| 1. Record the code | Note the code and any text shown, and photograph the display before resetting anything |
| 2. Identify the drive | Read the full model number from the nameplate, since the manual is specific to the series |
| 3. Find the fault table | Look in the troubleshooting or fault section of the manufacturer's manual for that code |
| 4. Check fault history | Many drives log recent faults and operating conditions at the time of the trip. Review them if available |
| 5. Look for a pattern | Note whether the fault happens at start, during acceleration, at speed, or while decelerating |
If you can't locate the manual, send IAC the drive's full model number and the code, and we can help find it or cross-reference the drive.
04 / Diagnosis Causes & First Checks
Check the cheap causes before blaming the drive
| Category | Common Causes | Check First |
|---|---|---|
| Overcurrent | Accel time too short, jammed or overloaded machine, motor or cable fault, wrong motor data entered | Mechanical load, accel time, and motor and cable condition |
| Overvoltage | Decel time too short for the load's inertia, regenerative load, high supply voltage | Decel time, supply voltage, and whether a braking resistor is needed |
| Undervoltage | Supply sag, loose power connections, blown fuse, momentary outage | Incoming voltage, fuses, and connection tightness |
| Overtemperature | Blocked airflow, failed fan, dirty heatsink, high ambient temperature, overload | Fans, filters, heatsink, and cabinet temperature |
| Ground fault / short | Damaged motor or cable insulation, moisture, a failed output stage | Motor and cable insulation, with power off and locked out |
| Phase loss | Blown input fuse, loose terminal, damaged cable, failed contactor | Fuses, terminals, and contactors on the input and output sides |
| Control & comms | Broken or noisy signal wiring, a disconnected cable, a network setting mismatch | Signal wiring, connectors, and communication settings |
Safety: a VFD's DC bus capacitors can hold a dangerous charge after power is removed. Lock out the supply, wait for the time the manufacturer specifies, and verify the bus has discharged before opening the drive or touching terminals. Work should be done by qualified personnel.
05 / Decision Clear, Fix, or Replace
Resetting is not the same as fixing
Most drives can be reset after a fault, and a one-off trip from a power blip may never return. But a fault that keeps coming back is telling you something. Repeatedly resetting a drive into an overcurrent or ground fault condition can do real damage to the drive and the motor.
Signs the drive itself may need replacing
- The same fault returns after the motor, cable, and load have been checked and ruled out
- The drive faults immediately on power-up or at the first run command with no load connected
- Visible damage such as burn marks, swollen capacitors, or a burnt smell
- A ground fault or short is reported with the motor and cable disconnected
- The display, keypad, or control board is unresponsive or behaving erratically
- The drive is old enough that repair parts or support are no longer available
When the drive does need replacing, match the replacement to the motor and application rather than just the old drive's horsepower, and be ready to re-enter the parameters. Ratings, fault interpretations, and replacement compatibility should be confirmed by a qualified engineer against the manufacturer's current documentation.
06 / Sourcing Getting a Replacement, Fast
Send us the drive and the code
If troubleshooting points to a failed drive, IAC can help find a replacement or a compatible alternative. Send the full model number from the nameplate and the fault code, and we'll check stock and cross-reference options, then quote.
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In-stock parts ordered before 4:00 PM Eastern ship same day. For urgent needs, call (877) 727-8757 during business hours — quote turnaround is typically under five minutes. You can also submit a part number via the quote form ↗ or email sales@iac.us.com.
Got the code? Get the quote.
Send IAC the drive model number and fault code, and we'll check stock and cross-reference replacements. Quotes in 5 minutes during business hours. Same-day shipping on in-stock units.