Hitachi 00900 fault code

What it means

The indoor sensor reads open or short circuit.

Safety: Safe isolation before disconnecting sensors or working on the PCB.

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 00900 on that machine.

00900 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

00900 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.