Hitachi 00601 fault code

What it means

OH (overheat) thermistor temperature rise (code 06)

The compressor/discharge overheat thermistor has seen too high a temperature — shortage of refrigerant, a restriction, or poor heat rejection driving discharge temperature up.

Safety: Discharge pipework runs very hot — allow to cool.

UK models this code applies to

From the Hitachi service literature we hold (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) — not a scraped list.

Now the harder half: proving what caused it

00601 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.