In short
- A fault stops the inverter and lights the red LED; a warning only blinks and the inverter keeps running.
- Battery voltage, overload and fan codes have simple causes you can check yourself.
- Bus voltage and current sensor faults that return after a restart need a technician.
Axpert inverters, and the many models built on the same platform under other names, share a fault table. The numbers below are the common ones; your manual may add or rename a few, so check it for your exact model before acting.
Fault or warning
A fault switches the inverter off and lights the red LED steadily. A warning makes the LED or the icon blink while the inverter keeps working. Many owners see warning 04 or 07 for months without a single real fault.
01: fan locked
The fan does not turn. Dust, an insect nest or a worn fan are the usual reasons. Switch off, let it cool, clean the fan. A replacement fan is cheap compared with an inverter that overheats.
03 and 04: battery voltage too high or too low
Code 04 is the classic one at the end of the night: the battery reached the low cut-off. Code 03 often comes from a charge voltage set too high for the battery, or a lithium BMS that disconnected during charge. Compare the battery settings in the menu with what your battery expects.
07: overload
More load than the inverter can supply, for too long. Kettles, heaters, pumps and air conditioners starting together are the usual suspects. The inverter may restart by itself after a pause, but the cause stays until you spread the loads.
08 and 52: bus voltage too high or too low
The internal DC bus left its window. A weak battery connection, a battery that collapses under a heavy start, or PV voltage above the limit can trigger it. If it returns without an obvious cause, call a technician.
51 and 58: overcurrent and output voltage too low
Often a short circuit or a heavy motor on the output. Unplug the loads, restart, then add them back one by one to find the guilty one.
See what happened before the code
Axpert Monitor reads the inverter through its RS232 port and records the battery voltage, the load and the warnings every few seconds. When a fault appears at 4 a.m., you can look back and see whether the battery sagged or the load jumped, instead of guessing.
Common questions
How do I reset an Axpert fault?
Most faults clear when you switch the inverter off and on again after the cause is gone. If the same code comes back at once, look for the cause before trying again.
Does Axpert Monitor show the fault codes?
It shows the warnings and faults the inverter reports on its RS232 port, with the values around them, on the screen, the dashboard and in Home Assistant.
Can the box change my battery settings to avoid code 04?
No. It only reads. Battery settings are changed on the inverter menu.
