BoilerFaultCodesTechnical description
Monitoring LON users: When there is no response from a user, values defaulted inside the control unit continue to be used for a further 20 minutes. Only then will a fault message be triggered.
What causes this fault?
This fault occurs when the boiler's main brain loses its connection to a secondary component or smart control accessory. The most common reason is a communication breakdown caused by loose wiring, a faulty connection module, or a malfunction in the main circuit board. While the boiler tries to cope using backup settings for a short period, it eventually triggers this code when it can no longer get the data it needs to operate efficiently.
DIY fix possible
Check that any external thermostats or control panels have power and are switched onTurn the boiler power off at the main isolation switch, wait 30 seconds, and turn it back on to reset the communication busInspect the cables connecting your thermostat to the boiler for any obvious signs of damage