Siemens G120 drives can display various fault codes to indicate different issues with the drive or the motor system. Here are some common fault codes for Siemens G120 drives and their potential meanings:

1. Internal error: This fault code indicates an internal error within the drive itself. It could be caused by various factors such as hardware malfunctions or firmware issues.

2. Overcurrent: Indicates that the drive has detected excessive current flow, which could be caused by overloading or a short circuit in the motor system.

3. Overtemperature: Indicates that the temperature of the drive or its components has exceeded the specified limit. This could be due to poor ventilation, excessive ambient temperature, or overloading.

4. Communication fault: Indicates a communication problem between the drive and external devices such as PLCs or control panels. Check the communication cables and settings.

5. Configuration fault: Indicates an error in the drive's configuration settings. Verify that all parameters are set correctly for your application.

6. Underload: Indicates that the load on the motor is too low. This could be caused by a disconnected or stalled motor, or an incorrect load setting in the drive.

7. Motor data identification fault: Indicates a problem with the motor data identification process. This process is used to determine the motor parameters for optimal control. Check motor connections and settings.

8. Brake fault: Indicates a fault with the motor brake system. This could be due to a malfunctioning brake or brake control circuit.

9. Phase loss: Indicates that one or more phases of the input power supply are missing. Check the power supply connections and ensure all phases are present.

10. Overvoltage: Indicates that the input voltage to the drive has exceeded the specified limit. This could be caused by voltage spikes or fluctuations in the power supply.

These are just a few examples of fault codes that may appear on Siemens G120 drives.