Your boiler has failed to ignite and cannot produce heat, which could be due to a gas supply issue, a blocked exhaust pipe, or an electrical wiring error.

Check gas supply, check flue system, check polarity

What causes this fault?

This fault occurs when the boiler's control system attempts to start a flame but fails to detect one after several attempts. It is physically caused by either a lack of fuel reaching the burner, a failure of the spark to ignite the gas, or a sensor that cannot 'see' the flame even if it is lit.