Code 120010: PCU temperature alarm
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical PCU temperature alarm 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
Definitions: The temperature sensor on the PCU modu le has reached the response threshold. Interface bit DB10.DB103.6 will be set. Remedy: Switch off the PCU and let it cool off. Improve the ventilation of the PCU module. Check the function of the fan of the PCU module (fan defect). If the error is displayed again, please inform the authorized service personnel. HMI-Alarms
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 120010 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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