Sunsynk F58 BMS communication fault - what should I do?
Short answer
F58 means the inverter lost communication with the battery's BMS while the 'BMS_Err-Stop' option was enabled, so it stopped using the battery. Check the battery is switched on, then call your installer to check the cable and battery settings. Sunsynk notes the option can be disabled on the LCD (fault document, March 2024, checked 24 September 2026).
Last checked 24 September 2026 · 1 source
What does this mean?
Disabling BMS_Err-Stop hides the symptom; installer should fix comms. W31 is the warning-level version (unstable comms).
What should I do first?
Record the code and current battery state before changing settings. Follow only the owner-safe reset steps in the manual.
When do I need an engineer?
Use an installer or manufacturer support route if the fault returns, involves isolation or protection, or the manual does not give an owner reset.
What to do next
If the system is hot, smoking, damaged or making unusual electrical noises, move away from it and follow the manufacturer emergency guidance.
Sources
- Sunsynk (via Herholdts) — hg-technical.herholdts.co.za/Technical/02%20Sunsynk/Technical/Fault%20Codes%20C…
Last checked: 24 September 2026