VFD Fault Codes: Common Errors and How to Fix Them

 

Understanding the most frequent VFD fault codes is essential for keeping industrial systems running smoothly. Whether you're responsible for day-to-day VFD maintenance or managing production uptime, quick diagnosis of these faults can save time, reduce downtime, and protect equipment from long-term damage.

This article provides a practical guide to common drive faults and offers troubleshooting steps to help maintenance teams respond effectively when issues occur.

What Are VFD Fault Codes?

Variable Frequency Drives (VFDs) use fault codes to indicate when something is wrong—electrical issues, overheating, motor faults, and more. These codes help technicians quickly identify the root cause without having to inspect every component manually.

Most VFDs regardless of brand use similar fault types, although exact codes and naming may vary slightly.

Most Common VFD Fault Codes

Below is a breakdown of the most common VFD fault codes and what they typically mean:

1. OC – Overcurrent Fault

• Possible Causes: Sudden load spikes, short circuits, or incorrect motor settings

• Action: Inspect motor wiring, check for mechanical jams, and verify load conditions

2. OV – Overvoltage Fault

• Possible Causes: High incoming voltage, braking issues, or poor energy dissipation

• Action: Monitor input voltage and consider installing a braking resistor

3. UV – Undervoltage Fault

• Possible Causes: Unstable power supply, loose cables, or temporary line drops

• Action: Check supply stability and inspect for poor electrical connections

4. OH – Overheating Fault

• Possible Causes: Blocked cooling, high ambient temperature, continuous overloading

• Action: Clean ventilation paths, inspect fans, and reduce load where necessary

5. GF – Ground Fault

• Possible Causes: Faulty insulation or moisture ingress

• Action: Perform insulation resistance tests and inspect motor cables for damage

6. CE – Communication Error

• Possible Causes: Network interruption or incorrect settings between the VFD and controller

• Action: Recheck communication protocols, cable connections, and termination settings

Read more: Essential Guide to Industrial Drives Maintenance for Optimal Efficiency

Why Preventive VFD Maintenance Matters

Many of these fault codes can be prevented or reduced through regular VFD maintenance. Scheduled inspections, cleaning, and monitoring can catch issues before they result in shutdowns.

Best practices include:

• Cleaning dust from VFDs and control panels

• Checking fan functionality and internal temperatures

• Monitoring input voltage stability

• Replacing aging capacitors or relays proactively

Well-maintained drives are less likely to throw unexpected faults and tend to operate more efficiently over time.

When to Consider Replacing a VFD

If a VFD starts displaying repeated or random faults even after proper troubleshooting, it might be nearing the end of its service life. Aging hardware, failing internal components, or outdated firmware can all contribute to frequent breakdowns.

Upgrading to a modern VFD not only improves fault diagnostics but can also enhance energy efficiency, reduce maintenance costs, and offer better remote monitoring options.

Conclusion

Having a clear understanding of the most common drive faults can help maintenance teams act quickly and minimize downtime. Combined with a solid maintenance routine, this knowledge becomes a key tool in ensuring operational stability and performance.