Cause : External fault comes when the drive has detected an issue with an external control circuit or device connected to it.

The EF error code on your Delta MS300 drive indicates an "External Fault". This means the drive has detected an issue with an external device or control circuit connected to it. Unlike error codes specific to internal drive components, the EF code is more general and can be triggered by various external factors.

1. Press RESET key after the fault is cleared.
2. Manual reset only after the external fault is cleared (terminal status is recovered).