Your boiler has detected an electrical communication problem with its internal control system which is preventing it from firing up.

DC supply pipe

What causes this fault?

This fault occurs when the boiler's internal computer loses the ability to communicate with the sensors that monitor the gas and water flow. It is usually caused by a physical break in the internal wiring or a failure in the electronic components on the main control board. Because the boiler can no longer verify that it is safe to operate, it shuts down immediately as a safety precaution.