Fujitsu Waterstage 18 flashes fault code

What it means

Inverter error

Source: Fujitsu Waterstage Super High Power D&T Manual, §Control System pp.03-3…03-5 — numeric display codes, interface-card LED pairs and outdoor-board flash counts with the published decode procedure

UK models this code applies to

18 flashes on these comes from each model's own manual, which may not match the meaning above — tap yours to read it.

Now the harder half: proving what caused it

18 flashes names a symptom, not a root cause. In the app, the same code opens a guided investigation: what to measure first, the expected values for your exact model, and an honest verdict — including “nothing in this machine is broken” when that's what the readings say.

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