No change on THW1/THW5 (<1 °C for 20 min from start), no rise after the booster heater starts, or THW1−THW2 < −5 °C for 10 min. Request code 567 shows 3/A/C for main/Zone-1/Zone-2 detection.
How to read it — ftc controller: Ecodan check codes show on the FTC / main controller display. (Ecodan service manual OCH727, §9-2 self-diagnosis action table)
UK models this code applies to
From the Mitsubishi Electric service literature we hold (Ecodan FTC service manual, error-code chapter + §10-6 thermistor tables) — not a scraped list.
L8 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.