What does error 0x8051 mean on a Felicity ESS?

0x8051 means: Aerosol operation alarm in battery pack. Aerosol operation (AI1 > 9V on any BMU as judged by SBCU).

Is error 0x8051 a fault or a warning?

0x8051 is a fault code: the ESS unit enters protection and stops normal operation until it is cleared.

0x8051

Aerosol operation alarm in battery pack

Critical — the ESS unit shuts down and latches a protection fault. Don't keep restarting it — the cause needs checking first.

Energy storage systemCritical

Aerosol operation alarm in battery pack

Cause: Aerosol operation (AI1 > 9V on any BMU as judged by SBCU).

Send faults externally, limit power, request lower high voltage; if command not received within 5s, cut off the main circuit relay.

Source: FLS-ES232LC-S.pdf

What does error 0x8051 mean on a Felicity ESS?: 0x8051 means: Aerosol operation alarm in battery pack. Aerosol operation (AI1 > 9V on any BMU as judged by SBCU).
Is error 0x8051 a fault or a warning?: 0x8051 is a fault code: the ESS unit enters protection and stops normal operation until it is cleared.
How do I clear or fix error 0x8051?: Send faults externally, limit power, request lower high voltage; if command not received within 5s, cut off the main circuit relay.

Compiled from official Felicity user manuals. Always consult your device manual and a qualified technician before performing repairs.