BoilerFaultCodesWhat the manual says
Manufacturer manualIgnition: Check the ignition module (control voltage 230 V across plugs X2.1 and X2.2) / Gas combination valve opens: Check the gas train (control voltage 230 V) and gas supply pressure / Ionisation current builds (higher than 5 µA): Check electrode adjustment and gas pipe for airlocks
What causes this fault?
This fault occurs when the boiler's control system attempts to start the burner but cannot detect a flame after several attempts. The most common reasons are a lack of gas reaching the unit, worn-out spark electrodes that fail to ignite the gas, or a faulty sensor that cannot 'see' the flame even if it has successfully lit.
This fault can occur in very cold weather if the external gas meter regulator freezes or if the condensate pipe is blocked by ice, preventing the burner from firing.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like F4: no call-out fees, no surprise bills.
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