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Fujitsu Waterstage 444 fault code

Fujitsu Waterstage heat pumps

What the Fujitsu Waterstage 444 fault code means, from the manufacturer's own service literature, and the UK models it applies to.

What it means

BX34 no function

BX34 no function

Source: Fujitsu Waterstage Comfort D&T Manual DA_CF001EF, §Control System pp.03-2…03-4 (official-distributor mirrors) — numeric display codes with Fujitsu's own reset and runs-despite-error columns, plus the interface-card LED table

UK models this code applies to

Tap yours to open 444 on that machine.

Now the harder half: proving what caused it

444 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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