Code UL4 (Fault): Undertorque Detection 2
Issue Description & Safety Warning
The Yaskawa V1000 AC Drive has triggered a critical Undertorque Detection 2 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Code type: Fault Manual section: Yaskawa V1000 Troubleshooting Parameter settings are not appropriate for the type of load. Check the settings of parameters L6-05 and L6-06. There is a fault on the machine side. Check the load for any problems.
Source: Yaskawa AC Drive V1000 Compact Vector Control Drive Technical Manual (SIEP C710606 19D)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Yaskawa V1000 AC Drive Alarms
Yaskawa controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code UL4 (Fault) on the V1000 AC Drive identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Yaskawa's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 153 Yaskawa V1000 AC Drive codes.
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