Inverex Nitrox F13 — Working Mode Change (Not a Grid Fault)

What it means: F13 is not a hardware fault and not a grid over-voltage. Inverex's own hybrid fault table, Chart 7-1, gives F13 as "Working mode change" and lists exactly what raises it: the grid type or grid frequency setting being changed, the battery mode being set to "No battery mode", and — on some older firmware versions — any change of the system work mode. The manual then says plainly that "generally, it will disappear automatically". F13 is the inverter acknowledging that a setting moved, not a report that something broke. On the Nitrox three-phase string inverters the same number is listed as "Reserved", so a string-inverter table cannot be used to read this code.

Why does Inverex show F13?

The Pakistan factor

The common Pakistani version of F13 is a commissioning artefact, not a grid problem. It shows up after an installer changes the grid standard or frequency during setup, and after the widespread practice of leaving a hybrid in "No battery mode" while a bank is on order or has been pulled out for replacement — the code then sits on the screen for weeks and gets misread as a fault. It is worth being blunt about the misdiagnosis: F13 is widely repeated locally as a grid over-voltage code, including in retailer listings and in an earlier version of this page. Chart 7-1 does not support that, and the advice that follows from it — widen the grid-voltage window — is actively wrong here, because it loosens a real protection to silence a message about a settings change. If your complaint genuinely is a high or collapsing feeder, the codes to look at are the grid-voltage family (F42 for low AC line voltage), not F13.

How to fix it (safe to try yourself)

  1. Ask what changed. If you, your installer or a remote monitoring session touched the grid standard, the grid frequency, the battery mode or the work mode in the minutes before F13 appeared, this is the expected response and not a fault.
  2. Wait. The manual states that F13 will generally disappear automatically. Give it a few minutes before doing anything else.
  3. Check whether the battery mode has been left on "No battery mode". The manual lists that selection as a direct cause of F13, and on a system that has a battery bank it is almost certainly wrong — it stops the inverter using the battery at all.
  4. If it has not cleared, power-cycle in the order the manual specifies — turn OFF the DC switch and the AC switch, wait a full minute, then turn the DC and AC switches back on. Do not skip the wait.
  5. Do NOT go changing grid-voltage or grid-frequency protection settings to chase this code. Those settings are not what F13 is reporting, and widening a grid protection window to clear an unrelated message removes the thing that stops a bad supply reaching your appliances.
  6. If F13 keeps returning on its own with nobody changing anything, stop and call your installer or an Inverex service centre. A work-mode code that raises itself repeatedly points at a settings or firmware problem in the commissioning, and that is their job — do not open the inverter.

References