Vaillant aroTHERM F.752 fault code

What it means

Frequency converter not recognised

Escalated from S.581: missing communication between the frequency converter and the outdoor unit's PCB. After three occurrences F.752 is displayed.

Safety: Safe isolation before opening terminal covers — mains present on the interconnect.

UK models this code applies to

From the Vaillant service literature we hold (Vaillant hydraulic station installation & maintenance instructions 0020257319 (VWL 57…127/5 IS), fault-message table) — not a scraped list.

Now the harder half: proving what caused it

F.752 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.