Siemens G120 F01000 - Causes & Fix

Siemens G120 F01000 — What It Means

The F01000 fault code on a Siemens SINAMICS G120 drive indicates an internal software error within the drive’s control unit, not a motor or power-stage problem. The drive has detected a fault in its own control software or firmware execution path. This fault triggers an OFF2 shutdown and requires acknowledgement by a complete POWER ON reset. The fault is logged in the drive’s diagnostic buffer, and the fault value stored in parameter r0949 is primarily for internal Siemens troubleshooting. The issue typically originates in the Control Unit (CU) itself, whether from corrupted parameter data, firmware instability, memory-card issues, or an actual control-board hardware failure.

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Common Causes

• Corrupted parameter or data state The drive’s stored parameter set or project data has become inconsistent or corrupted, causing the control software to fail during execution.
• Firmware instability or version mismatch Outdated or incompatible firmware can trigger internal software faults during drive operation or startup.
• Memory card or non-volatile storage fault A failing or corrupted memory card or internal non-volatile memory prevents the control unit from loading valid configuration data.
• Control Unit hardware failure Physical failure of components on the control board itself can disrupt normal software execution and generate this fault.
• Improper power-down or reset sequence An incomplete or interrupted power-off cycle can leave the control unit in an inconsistent state that triggers F01000 on restart.

Step-by-Step Fix

1. {‘lead’: ‘Read the fault buffer and diagnostics’, ‘text’: ‘Access parameters r0945 (fault buffer) and r0949 (fault value) using the BOP or commissioning software to capture the full diagnostic context before clearing the fault.’}
2. {‘lead’: ‘Perform a complete POWER ON reset’, ‘text’: ‘Remove all power from the drive and wait at least 30 seconds, then restore power to all components. Do not rely on a keypad or software reset alone.’}
3. {‘lead’: ‘Inspect and reseat the memory card’, ‘text’: ‘Remove the memory card (if installed), check for physical damage or dirt on the contacts, clean if needed, and reseat it firmly. If you have a backup, try a known-good memory card.’}
4. {‘lead’: ‘Check for available firmware updates’, ‘text’: ‘Consult the Siemens support portal or your drive documentation for the latest firmware version for your G120 model and upgrade if a newer release addresses known software issues.’}
5. {‘lead’: ‘Review recent parameter changes’, ‘text’: ‘If the fault appeared after commissioning or parameter adjustments, reload a known-good parameter backup or perform a factory reset and recommission the drive.’}
6. {‘lead’: ‘Monitor the drive through several startup cycles’, ‘text’: ‘Run the drive under normal load and observe whether F01000 recurs. If the fault returns immediately on every power-up, the Control Unit likely requires replacement.’}
7. {‘lead’: ‘Replace the Control Unit if fault persists’, ‘text’: ‘If all software and data checks pass and the fault continues to appear after power-on, order and install a replacement CU assembly for your G120 model. Transfer your configuration via memory card or recomission from scratch.’}

Parts Often Needed

When to Call a Pro

Call a qualified Siemens-certified technician or automation integrator if you are not comfortable working with VFD firmware updates, parameter backups, or Control Unit replacement. If the fault recurs after a power cycle and you cannot access the drive’s diagnostic parameters or commissioning software, professional support is necessary to correctly interpret the fault buffer and perform CU-level diagnostics. Because F01000 is an internal software fault, troubleshooting requires familiarity with Siemens STARTER or Drive-CLiQ tools, and incorrect firmware or parameter handling can result in extended downtime or loss of your application configuration.