Hitachi 00401 fault code

What it means

The inverter could not commutate/switch the compressor correctly — a start/drive failure.

Safety: Safe isolation before disconnecting the compressor or testing the inverter board — capacitors hold charge.

Source: Hitachi Technical Catalogue §9.10 / §10.1.2 Error Code Information (RAK-PSES(W)/RAC-WSE — Hitachi UK; RAK-PED/RAC-WED — Hitachi R32 catalogue), both render-verified

UK models this code applies to

Tap yours to open 00401 on that machine.

00401 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

00401 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.

Free, no sign-up. Pick the model: where we hold a chart for it, it takes you through one question at a time.

Or use it in your browser on any phone or laptop.