Code 231-8040: Heat sink temp. in UV 1xx
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Heat sink temp. in UV 1xx 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
[Cause of error] - Heat-sink temperature of UV 1xx power supply unit too high - Temperature in the electrical cabinet too high - Contaminated filter pads - Defective climate control unit in the electrical cabinet - Defective fan in the UV - Defective temperature sensor - If the heat-sink temperature continues to increase, the unit will be switched off [Error correction] - Stop the machine and let it cool down - Continue working with lower power (reduce the feed rate) - Clean the filter pads - Check the climate control unit in the electrical cabinet - Inform your service agency
Source: HEIDENHAIN NC Error Messages — TNC7/640/620/320/128, CNC PILOT 640, MANUALplus 620 (10/2023)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Heidenhain TNC Series CNC Alarms
Heidenhain controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 231-8040 on the TNC Series CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Heidenhain's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4497 Heidenhain TNC Series CNC codes.
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