Error code 40 display on Quantum. What is this?

Communication issue between User Interface & Charge Controller

If new install 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.

If possible you should check the following items and if they are not correct you should contact your installer prior to raising a ticket for a service call.


      • Have the trips in your consumer unit switched off?  (switch back on if they have)
      • Check that the switches controlling the supplies to your product are on
        • There should be a switch (unfused) for the off peak supply
        • The continuous supply should not be on a plug
      • Are the supply cables different sizes, off peak supply should be on a 2.5mm2 cable
      • Have you set up the user interface (control on the top of the product correctly?
      • Have you registered your product

Applicable to: QM050RF QM070RF QM100RF QM125RF QM150RF
Series G5 onwards and also Series Z & Y.

Require additional help? Please follow link below

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