The Siemens code is not a permanent hardware fault, but rather a warning alarm indicating that the Motor Data Identification (motor tuning) is active. While this is a standard part of the commissioning process for SINAMICS drives like the G120 or G120C, it can be frustrating if it prevents the drive from starting in normal operation. Review of Fault A07991
Depending on your current stage of setup, you can either complete the identification or bypass it: Ensure the motor is safe to run and properly connected . siemens fault 0a7991
Issue – Fault A07991 cannot be cleared on SINAMICS G120C drive The Siemens code is not a permanent hardware