Panasonic Aquarea H43 fault code

What it means

Abnormal water temperature sensor, Zone 1

With the optional PCB (CZ-NS4P) fitted the system needs a zone water sensor and cannot see it. H44 is the Zone 2 twin.

UK models this code applies to

From the Panasonic service literature we hold (Panasonic Aquarea installation guide 1.2 (Monobloc H & J generation, ProClub UK) — Error Codes during commissioning) — not a scraped list.

Now the harder half: proving what caused it

H43 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.