Mitsubishi Electric Mitsubishi Ecodan R290 (PUZ-WZ) fault codes
Built 2023 onwards
The PUZ-WZ monobloc range, 5 to 12 kW, on R290. Same FTC codes and the same U, F and A rule, but R290 is a hydrocarbon, not an F-gas: Mitsubishi describe it as a highly flammable refrigerant, and the outdoor unit is trained-installer work rather than F-Gas certified work by law. The U1 high pressure switch trips at 3.2 MPa on this range rather than 4.15 MPa.
Codes on the Mitsubishi Ecodan R290 (PUZ-WZ) follow the same Mitsubishi Electric scheme as the rest of the range. Where a code behaves differently on this generation, the code page says so.
Mitsubishi Electric fault codes
Every published Mitsubishi Electric code. Open a code to see which models and years it applies to.
- U1High pressure: the outdoor unit’s 63H pressure switch has tripped, at 4.15 MPa on R410A and R32 Ecodans and 3.2 MPa on the R290 range. Mitsubishi say it is usually water flow.Get it checked
- L9Low flow on the primary circuit. Formally an installer job, but the causes are things you can often see — a dirty filter, a closed valve, air after radiator work.Get it checked
- No code and nothing happeningMitsubishi resolve four in five support calls on the phone, and publish the four common issues behind them. Three take two minutes and none of them is a code.Get it checked
- EFA code Mitsubishi define as "non defined": noise on the wiring between the controller, the FTC and the outdoor unit. Their published remedy is to power the Ecodan down for thirty seconds.Get it checked
- Outdoor unit failureAny code starting U, F or A means the outdoor unit; Mitsubishi publish that rule themselves. It is the refrigerant side: F-Gas work on R410A and R32 Ecodans, trained-installer work on the R290 range.Get it checked
- L3Circulation water temperature overheat protection. The flow rate has probably dropped, and Mitsubishi list three things to check: a water leak, a blocked strainer and the pump.Get it checked
- J1The wireless receiver cannot hear the wireless room controller. Mitsubishi’s first check is the controller’s batteries, and J1 to J8 all mean the same thing.Get it checked
- P6Plate heat exchanger protection, usually against freezing. Mitsubishi send the engineer to the L3 flow checks, then to the refrigerant charge, which is F-Gas work on R410A and R32 units.Get it checked
- L4The cylinder has overheated. Often the immersion heater running when it should not — which is also the fault that quietly doubles your electricity bill.Get it checked