Mitsubishi Electric heat-pump — Ecodan FTC5 cylinder units, EHPT20X-MHCW and EHST20(D)(C)-MHCW Error Codes Directory
Complete diagnostic reference for Mitsubishi Electric heat-pump — Ecodan FTC5 cylinder units, EHPT20X-MHCW and EHST20(D)(C)-MHCW fault codes. Each code includes official root causes, safety precautions, and affected replacement components.
Ecodan L9: three different flow faults share one code
L9 means the control has measured low flow in a primary water circuit. The manual lists it three times for three circuits: heat source side sensed by the flow sensor, then Zone1 and Zone2, each sensed by a flow switch. The digit shown in Request code 569 under Running information tells you which of the three it is. It reports a measurement, not a failed pump. Applies to: Ecodan FTC5 cylinder units, EHPT20X-MHCW and EHST20(D)(C)-MHCW Scoped to the FTC5 controller as documented in the EHPT20X-MHCW and EHST20(D)(C)-MHCW cylinder service manual. Later FTC generations and the newer Ecodan ranges carry their own code tables, and a code letter shared between two controllers is not a shared meaning. Owner-safe checks: Read the fault code and then look up Request code 569 in Running information on the main controller, and write down the digit shown. | Photograph the outdoor unit model number on the data plate, since the recommended flow range is per model. | Note the system pressure on the gauge and whether the pressure has been falling, since a leak is on the manufacturer's cause list. | Record whether the code appears at start-up or during steady running, and whether the circuit has been opened recently. | Check that no radiator valve or zone valve has been closed off since the system last ran normally. Qualified technician: Strainer cleaning, purging a sealed system, and any work that breaks into the water circuit belong to the installer or a qualified heating engineer. | Electrical testing of the flow sensor, the flow switch, the CN1A connector, and the IN2, IN3, and IN7 terminals is technician work on a live control. | DIP switch settings on the FTC board are commissioning parameters, and changing one without knowing which circuits exist can hide the fault rather than clear it. | Replacing or resizing the circulation pump is a design decision about system head, not a parts swap.