IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 43 for active-islanding alarm
Felicity 43 error code
BUS under-voltage fault (solid LED): the internal DC bus failed to hold its working voltage; in the warning list the same number is the active-islanding alarm raised when the grid fails (flashing LED).
Likely causes
- Internal DC-bus regulation fault
- Battery voltage collapsing under load
- Large load transient pulling the bus down
- Grid outage, which raises the warning variant by design
Checks to run, in order
- 1Note whether the fault LED is solid (fault) or flashing (warning)
- 2If flashing, confirm whether the grid is actually absent - islanding detection is normal protective behaviour
- 3If solid, measure the battery voltage and the load
- 4Restart 2-3 times and see whether the code returns under load
Fixes
- For the warning, wait for the grid to return; no repair is needed if the outage is real
- For the fault, reduce the load and restart
- If the solid fault returns, book service
When to escalate
If code 43 is solid with a healthy battery and moderate load, escalate for DC-bus service; a flashing 43 during a real outage needs no action.
Fix it with the right tools
Check the system around the fault before replacing parts: load, battery bank, PV string and commissioning settings. If you need a second opinion, send the code and your inverter model to our team.
Before you open the inverter
- Isolate both the AC and DC sides, then confirm the display is dead before touching terminals.
- Use insulated tools and one hand where possible. DC arcs do not self-extinguish like AC.
- If you see burnt terminals, swollen cells, leaking electrolyte or a burning smell, stop and escalate instead of resetting the fault.
Questions installers ask
What does Felicity 43 mean?
BUS under-voltage fault (solid LED): the internal DC bus failed to hold its working voltage; in the warning list the same number is the active-islanding alarm raised when the grid fails (flashing LED).
How do I fix Felicity 43?
For the warning, wait for the grid to return; no repair is needed if the outage is real For the fault, reduce the load and restart If the solid fault returns, book service
When should I escalate Felicity 43?
If code 43 is solid with a healthy battery and moderate load, escalate for DC-bus service; a flashing 43 during a real outage needs no action.
Can I reset Felicity 43 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity 43 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity 43?
Felicity 43 is documented for IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 43 for active-islanding alarm. Confirm the code on your own unit's display or manual before ordering parts.
More Felicity error codes
- Felicity 04Low cell voltage / over-discharge protection.
- Felicity 05PV over-current fault: the PV input current exceeded the inverter's PV input limit.
- Felicity 18PV short-circuit fault on the PV input; in the warning list the same number means battery under-voltage alarm.
- Felicity 19Battery open-circuit alarm: the inverter no longer detects a battery on its terminals.
- Felicity 20Battery SOC low alarm: the battery's state of charge has fallen to the low-SOC warning threshold.
- Felicity 21BMS communication alarm: abnormal communication between battery and inverter in non-SOC mode.
Guidance reviewed 17 October 2026 by the Mishka Energy installer team. Error codes vary by brand, model family and firmware; confirm against the manufacturer manual.
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