What do Fox Evo 'BMS State BS1 E01' style codes mean?
Short answer
They are battery flags shown on the Evo's screen. Fox's Evo manual lists six registers, BS1 to BS6, and each hex value from E01 to E80 is one fault. Values add together, so BS1 E03 means inverter-communication plus internal-communication faults. Voltage, current and temperature flags usually clear on their own. Faults such as 'cell 0V' need Fox support.
Last checked 24 September 2026 · 1 source
What does this mean?
BS1 holds communication, over- and under-voltage, over-current and temperature flags. BS2 holds sensor, relay and cell-imbalance flags. BS5 and BS6 hold permanent faults, such as low SOH (state of health), a cell at 0 V or a hardware short-circuit current.
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
- solartradesales.co.uk — www.solartradesales.co.uk/Cache/Downloads/EN-EVO-User-Manual.pdf
Last checked: 24 September 2026