Isolate Mains Power to appliance as per TOPs P4
Fault codes not listed in the normal fault finding may be due to:
  • Water inside PCB
  • Water on electrical plugs or components
  • The appliance set to MAX or MIN service mode (check gas valve mode switch)
    Also note that in fault conditions the fault will display in addition to any demand.
    E.g. Below is fault code J (air flow fault) with a CH demand.