The heater shows FAULT 40 error code. (Series G6)

Communication issue between User Interface & Charge Controller

Is this a new install & is the installer still with the heater?

YES

if the installer is still with the heater ask the installer to switch off the heater at the supply (or both supplies) and make sure the supplies are dead.

Ask them to remove the right hand & front cover so they can clearly see the Charge Controller PCB.

Ask them to check the UI cable is plugged into the PCB. See picture below.

If the plug was loose or not plugged in, hopefully pushing it back in will resolve the issue.

Once covers are on and heater is powered up, the heater should work OK.

If FAULT 40 persists, raise an engineer visit - Take Charge Controller & User Interface.

NO

If the installer isn't with the product send engineer with a new charge controller and user interface.