Mitsubishi Ecodan P8 fault code
Mitsubishi Ecodan heat pumps
What it means
Refrigerant circuit abnormality
Detected from pipe-temperature relationships (manual: TH6–THW2 ≤ 1 °C / TH7–TH3 ≤ 1 °C at ≥ 61 Hz) — refrigerant not doing what the mode demands.
Safety: R32/R290 (model-dependent): flammable refrigerant — leak-check with suitable equipment and ventilate.
UK models this code applies to
From the Mitsubishi Electric service literature we hold (Ecodan service manual OCH727 §9-2) — not a scraped list.
Ecodan PUZ-WM50VHA (R32)Ecodan PUZ-WM60VAA (R32)Ecodan PUZ-WM85VAA (R32)Ecodan PUZ-WM85YAA 3-phase (R32)Ecodan PUZ-WM112VAA (R32)Ecodan PUZ-WM112YAA 3-phase (R32)Ecodan PUZ-WZ50VAA (R290)Ecodan PUZ-WZ60VAA (R290)Ecodan PUZ-WZ85VAA (R290)Ecodan PUZ-WZ85YAA 3-phase (R290)Ecodan PUZ-WZ100VAA (R290)Ecodan PUZ-WZ100YAA 3-phase (R290)Ecodan PUZ-WZ120VAA (R290)Ecodan PUZ-WZ120YAA 3-phase (R290)
Now the harder half: proving what caused it
P8 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.
Chase this code in the app →